ARRT MRI Exam — Questions and Answers

Question 1: Which k-space trajectory fills the center of k-space first, providing low-spatial-frequency (contrast) information early in the acquisition and reducing motion sensitivity?

Reverse linear ordering
EPI single-shot trajectory
Linear (sequential) k-space filling
Centric (elliptic centric) k-space ordering (Correct answer)

Correct answer: Centric (elliptic centric) k-space ordering

Centric k-space ordering acquires the low-frequency center of k-space at the beginning of the scan, capturing image contrast during peak enhancement and minimizing motion effects on image quality.

Question 2: Which sequence uses both magnitude and phase data from a high-resolution 3D gradient echo acquisition to highlight hemosiderin, deoxyhemoglobin, and calcification?

Susceptibility-weighted imaging (SWI) (Correct answer)
Double inversion recovery
Diffusion tensor imaging
Arterial spin labeling

Correct answer: Susceptibility-weighted imaging (SWI)

SWI combines magnitude and filtered phase images to greatly increase sensitivity to susceptibility differences such as blood products and calcium.

Question 3: Iron oxide nanoparticles (e.g., USPIO) used as MRI contrast agents primarily shorten which relaxation time?

T2 and T2* (susceptibility effect) (Correct answer)
T2 only with no T2* effect
Neither T1 nor T2
T1 only

Correct answer: T2 and T2* (susceptibility effect)

Iron oxide particles create local magnetic field inhomogeneities that predominantly shorten T2 and T2*, causing signal loss (darkening) on T2-weighted and gradient echo images.

Question 4: Which force on a ferromagnetic object depends most directly on the spatial field gradient, not just field strength?

Translational (projectile) force (Correct answer)
Torque
Lorentz force on blood
RF heating

Correct answer: Translational (projectile) force

Translational attraction depends on the spatial gradient of the static field, which is often greatest near the bore entrance.

Question 5: Which technique is most effective for reducing susceptibility artifact from a metallic implant in MRI?

Increase the slice thickness
Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth (Correct answer)
Use a gradient-echo sequence
Increase TE

Correct answer: Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth

Spin-echo and FSE sequences use 180° refocusing pulses that compensate for susceptibility-induced dephasing, and a narrow bandwidth reduces chemical shift but a wide bandwidth reduces susceptibility — MARS protocols use high bandwidth FSE.

Question 6: Increasing the echo train length (ETL) in a fast spin echo sequence while other parameters stay the same will:

Shorten scan time but increase image blurring and decrease the number of slices per TR (Correct answer)
Increase the number of slices per TR and improve T1 weighting
Increase scan time and reduce blurring
Have no effect on scan time

Correct answer: Shorten scan time but increase image blurring and decrease the number of slices per TR

A longer ETL fills more k-space lines per TR, reducing scan time but adding T2 blurring and taking more time per slice in each TR.

Question 7: Fat and water are imaged with a two-point Dixon technique at 1.5 T. Which pair of TEs is most appropriate for opposed-phase and in-phase images?

1.1 ms and 2.2 ms
4.4 ms and 8.8 ms
10 ms and 20 ms
2.2 ms and 4.4 ms (Correct answer)

Correct answer: 2.2 ms and 4.4 ms

At 1.5 T, fat and water are about 220 Hz apart, so they are opposed-phase near 2.2 ms and in-phase near 4.4 ms.

Question 8: This kind of magnetic shielding confines the main magnet's field by using other magnets and their corresponding magnetic fields.

Passive
Active (Correct answer)

Correct answer: Active

Active magnetic shielding uses additional superconducting coils, placed around the main magnet, that generate opposing magnetic fields. These opposing fields effectively cancel out the main magnet's fringe field at a certain distance. This method significantly reduces the extent of the stray magnetic field outside the scanner, making it a more complex but often more effective and lighter shielding solution than passive methods.

Question 9: What does k-space represent in MRI?

The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform (Correct answer)
The frequency range of the RF pulse
The physical space inside the magnet bore
The gradient amplitude map

Correct answer: The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform

K-space is the mathematical data domain where raw MRI signal is stored as spatial frequencies; a Fourier transform converts k-space data into the final diagnostic image.

Question 10: Which parameter in MRI controls the field of view (FOV) and therefore directly affects spatial resolution when matrix size is held constant?

TR
TE
FOV size relative to matrix (voxel size = FOV/matrix) (Correct answer)
Receiver bandwidth

Correct answer: FOV size relative to matrix (voxel size = FOV/matrix)

Voxel size = FOV divided by matrix; decreasing FOV while maintaining matrix size decreases voxel size, increasing spatial resolution but reducing SNR.

Question 11: T2* relaxation differs from T2 relaxation primarily because T2* includes:

Chemical shift effects only
Magnetic field inhomogeneities in addition to spin-spin interactions (Correct answer)
Only spin-lattice interactions
Gradient-induced dephasing only

Correct answer: Magnetic field inhomogeneities in addition to spin-spin interactions

T2* accounts for both intrinsic spin-spin relaxation (T2) and additional dephasing caused by local magnetic field inhomogeneities.

Question 12: A technologist adds a -90° 'flip-back' pulse at the end of each echo train in a fast spin echo sequence. What is the main benefit?

It eliminates the need for phase encoding
It suppresses the fat signal more uniformly
It returns residual transverse magnetization to the longitudinal axis, allowing bright fluid with a shorter TR (Correct answer)
It removes chemical shift artifact in the frequency direction

Correct answer: It returns residual transverse magnetization to the longitudinal axis, allowing bright fluid with a shorter TR

Driven equilibrium (DRIVE/FRFSE/RESTORE) flips leftover transverse magnetization back to +Z so fluid stays bright on T2 images with a reduced TR.

Question 13: Which sequence is a 3D T1-weighted gradient echo with an inversion recovery preparation pulse, widely used for volumetric brain imaging?

HASTE
PROPELLER
FIESTA
MPRAGE (Correct answer)

Correct answer: MPRAGE

MPRAGE (magnetization-prepared rapid gradient echo) uses an inversion pulse before a fast 3D GRE readout to give strong gray-white T1 contrast.

Question 14: A technologist wants to reduce scan time while maintaining similar SNR. Which strategy is most effective?

Increase the repetition time (TR)
Decrease the matrix size
Use parallel imaging (SENSE/GRAPPA) (Correct answer)
Increase slice thickness

Correct answer: Use parallel imaging (SENSE/GRAPPA)

Parallel imaging techniques use multiple coil elements to under-sample k-space, reducing scan time while maintaining acceptable SNR through reconstruction algorithms.

Question 15: How does increasing the echo train length (ETL) in a fast spin echo (FSE) sequence affect image quality?

Spatial resolution improves in all directions
SNR improves proportional to ETL
T1 contrast increases significantly
Scan time decreases but T2 blurring may increase (Correct answer)

Correct answer: Scan time decreases but T2 blurring may increase

Longer ETL fills k-space faster (reducing scan time) but each echo has progressively more T2 decay, causing blurring particularly of edges and fine detail.

Question 16: A method of expressing the gradient performance in terms of T/m/s, which is the gradient magnetic field's acceleration to its maximum amplitude.

Coil configuration
Rise time
Slew rate (Correct answer)

Correct answer: Slew rate

Slew rate is a critical performance metric for MRI gradient coils, measuring how quickly a gradient can reach its maximum strength. It is expressed in Tesla per meter per second (T/m/s), representing the acceleration of the gradient magnetic field. A higher slew rate allows for faster switching of gradients, which translates to quicker image acquisition and shorter echo times, improving overall scan efficiency.

Question 17: If all other parameters stay the same, how does SAR change when a patient moves from a 1.5T to a 3T scanner?

It is cut in half
It doubles
It stays the same
It roughly quadruples (Correct answer)

Correct answer: It roughly quadruples

SAR is proportional to the square of the static field strength, so doubling B0 roughly quadruples SAR.

Question 18: What is the effect of increasing receiver bandwidth on MRI image quality?

SNR decreases but chemical shift artifact is reduced (Correct answer)
SNR increases and scan time decreases
Image contrast improves significantly
Spatial resolution decreases

Correct answer: SNR decreases but chemical shift artifact is reduced

Increasing bandwidth reduces chemical shift artifact and allows shorter TE/TR, but more noise is accepted per unit time, lowering SNR.

Question 19: Gadolinium retention in the brain has been observed particularly in which structure on unenhanced T1-weighted images in patients receiving multiple GBCA doses?

Caudate nucleus
Thalamus
Dentate nucleus of the cerebellum (Correct answer)
Hippocampus

Correct answer: Dentate nucleus of the cerebellum

Gadolinium deposition in the dentate nucleus and globus pallidus manifests as T1 hyperintensity on unenhanced brain MRI after multiple GBCA administrations.

Question 20: Which coil type generally provides the highest SNR for imaging a small superficial structure?

Surface coil (Correct answer)
Volume coil
Body coil
Quadrature head coil

Correct answer: Surface coil

Surface coils placed close to the target anatomy have superior SNR for small or superficial structures because they detect signal from a limited volume with less noise.

Question 21: Time-of-flight MRA makes flowing blood bright mainly because:

Phase shifts are proportional to flow velocity
Blood has a much longer T2 than surrounding tissue
Fresh unsaturated spins enter the slice while stationary tissue is saturated by repeated short-TR pulses (Correct answer)
Gadolinium shortens the T1 of blood

Correct answer: Fresh unsaturated spins enter the slice while stationary tissue is saturated by repeated short-TR pulses

TOF uses flow-related enhancement: inflowing fully magnetized blood gives strong signal compared with saturated stationary tissue.

Question 22: Which standard governs the format and network transfer of MR images between the scanner, workstations, and PACS?

HIPAA
DICOM (Correct answer)
JPEG 2000
HL7

Correct answer: DICOM

DICOM (Digital Imaging and Communications in Medicine) is the standard for storing, formatting, and transmitting medical images and their metadata between modalities, PACS, and viewing stations. HL7 handles text-based clinical and administrative messages. HIPAA is a privacy law, not an image format.

Question 23: Which type of aneurysm clip is considered MR Unsafe regardless of age or appearance?

Titanium clips
Ferromagnetic stainless steel clips (Correct answer)
Cobalt-chromium clips
Platinum clips

Correct answer: Ferromagnetic stainless steel clips

Ferromagnetic stainless steel aneurysm clips are MR Unsafe because the static field can exert significant torque on the clip, risking rupture of the aneurysm.

Question 24: On a coronal MRI of the knee, which structure appears as a low-signal C-shaped band along the tibial plateau?

Iliotibial band
Medial meniscus (Correct answer)
Anterior cruciate ligament
Posterior cruciate ligament

Correct answer: Medial meniscus

The medial meniscus appears as a low-signal C-shaped (bow-tie) structure on coronal images along the medial tibial plateau.

Question 25: A double inversion recovery preparation is commonly used in cardiac MRI to:

Null fat and water at the same time to show the coronary arteries
Increase signal from gadolinium in the blood pool
Produce black-blood images by nulling the signal from flowing blood (Correct answer)
Measure myocardial T2* for iron overload

Correct answer: Produce black-blood images by nulling the signal from flowing blood

A non-selective inversion followed by slice-selective re-inversion nulls blood that flows into the slice, giving black-blood images of the myocardium.

Question 26: In contrast to the spin echo sequence (SE), the gradient echo sequence (GRE)

possesses a 180-degree pulse and T2* dephasing.
has a T2 dephasing pattern and no 180-degree pulse.
has T2* dephasing and lacks a 180-degree pulse. (Correct answer)
possesses a 180-degree pulse and T2 dephasing

Correct answer: has T2* dephasing and lacks a 180-degree pulse.

Gradient Echo (GRE) sequences fundamentally differ from Spin Echo (SE) sequences because they do not use a 180-degree radiofrequency refocusing pulse. Instead, GRE sequences employ a gradient reversal to rephase the spins and create an echo. Since there is no 180-degree pulse to correct for static magnetic field inhomogeneities, GRE sequences are sensitive to T2* dephasing, making them more prone to susceptibility artifacts than SE sequences.

Question 27: Dynamic susceptibility contrast (DSC) perfusion imaging of the brain relies on which effect during the first pass of a gadolinium bolus?

Labeling of arterial water with an inversion pulse
Transient T2* signal loss on rapid gradient echo EPI images (Correct answer)
Magnetization transfer between bound and free water
T1 shortening that increases signal on spin echo images

Correct answer: Transient T2* signal loss on rapid gradient echo EPI images

Concentrated gadolinium in the capillaries creates local susceptibility gradients, causing a temporary T2* signal drop that is tracked over time.

Question 28: Phase contrast MRI (PC-MRI) is primarily used to measure:

Chemical metabolite concentrations
Myelin content
Velocity and flow of fluids such as blood and CSF (Correct answer)
Tissue T1 values

Correct answer: Velocity and flow of fluids such as blood and CSF

PC-MRI encodes velocity as phase shifts of moving spins, allowing quantitative measurement of blood flow velocity and volume, and CSF pulsation.

Question 29: What is the main purpose of having a patient avoid crossed legs or hands clasped during scanning?

To prevent conductive loops that can cause RF burns (Correct answer)
To reduce motion artifact
To lower acoustic noise
To improve coil sensitivity

Correct answer: To prevent conductive loops that can cause RF burns

Skin-to-skin contact can form a closed conductive loop in which RF energy induces current, causing burns.

Question 30: In MR angiography, time-of-flight (TOF) technique produces vascular signal by exploiting which physical principle?

Inflow enhancement: unsaturated blood entering a saturated imaging slab (Correct answer)
T1 shortening by gadolinium contrast
Chemical shift between blood and surrounding fat
T2 prolongation of blood

Correct answer: Inflow enhancement: unsaturated blood entering a saturated imaging slab

TOF MRA relies on flow-related enhancement: flowing unsaturated blood entering a slice that has saturated stationary tissue appears bright relative to background.

Question 31: The signal-to-noise ratio (SNR) in MRI is proportional to which of the following?

Flip angle / repetition time
Voxel volume × √(NEX) × √(scan time factors) (Correct answer)
1 / (TR × TE)
Field of view / matrix size only

Correct answer: Voxel volume × √(NEX) × √(scan time factors)

SNR increases with larger voxel volume, more signal averages (NEX), and longer acquisition times that allow more k-space sampling.

Question 32: A 'DC offset' or 'center dot' artifact seen as a bright spot in the center of the image is related to:

A small DC current offset in the receiver causing a spike in the center of k-space (Correct answer)
Patient positioning off-isocenter
B1 field inhomogeneity
Excessive TR causing saturation effects

Correct answer: A small DC current offset in the receiver causing a spike in the center of k-space

A DC offset artifact occurs when a constant voltage offset in the MR receiver chain introduces a spike at the origin of k-space (DC component), appearing as a bright dot at image center.

Question 33: This magnet has a strength of up to 0.3 T, can be switched off, and can be used in both horizontal and vertical field systems.

Selenoid magnet
Permanent magnet
Resistive magnet (Correct answer)
Superconducting

Correct answer: Resistive magnet

Resistive magnets consist of coils of wire through which a large electric current is continuously passed to generate a magnetic field. They can be switched off, offer field strengths typically up to 0.3 Tesla, and can be designed for both horizontal and vertical field orientations. However, they require significant continuous power and generate substantial heat, limiting their use in high-field MRI.

Question 34: What is the primary trade-off when reducing the field of view (FOV) in MRI?

Improved SNR with no change in resolution
Increased slice coverage with same resolution
Improved spatial resolution but increased risk of aliasing artifacts (Correct answer)
Decreased scan time and improved SNR

Correct answer: Improved spatial resolution but increased risk of aliasing artifacts

Reducing FOV increases spatial resolution by making voxels smaller, but if anatomy extends beyond the reduced FOV, aliasing (wrap-around) artifacts occur.

Question 35: Require the employment of solenoid coils because of the B0's orientation; these coils are more effective than linear coils and can be electrically combined with other coils to enhance signal homogeneity across an area of interest.

Helmholtz pair
Vertical (Correct answer)
Phased array
Quadrature

Correct answer: Vertical

Vertical coils are specifically designed for MRI systems where the main magnetic field (B0) is oriented vertically, often found in open or permanent magnet systems. These coils are more effective than linear coils in this orientation and can be electrically combined with other coils to enhance signal homogeneity across the area of interest, optimizing signal reception for vertical field systems.

Question 36: What is the primary advantage of using a higher-relaxivity GBCA (e.g., gadobenate dimeglumine) compared to a standard-relaxivity agent?

It crosses the blood-brain barrier more readily
It can be used at a lower dose to achieve comparable enhancement (Correct answer)
It is completely renally safe at any dose
It eliminates the need for dynamic imaging

Correct answer: It can be used at a lower dose to achieve comparable enhancement

Higher relaxivity means greater T1 shortening per unit concentration, so a lower molar dose can produce equivalent or superior enhancement compared to standard agents.

Question 37: Which of the following best describes the purpose of the ARRT MRI 'didactic' requirement in the post-primary pathway?

Shadowing a radiologist for 40 hours
Completion of a formal coursework curriculum covering MRI physics, procedures, and patient care (Correct answer)
Attending at least one MRI conference per year
Passing a vendor-specific MRI operations test

Correct answer: Completion of a formal coursework curriculum covering MRI physics, procedures, and patient care

The didactic requirement ensures candidates have formal academic instruction in MRI-specific knowledge areas before sitting for the registry.

Question 38: The gradient subsystem's primary goal is to

Choose the plane of slices.
Choose the imaging plane.
Encode the MR signal spatially
Everything mentioned (Correct answer)

Correct answer: Everything mentioned

The gradient subsystem is crucial for multiple functions in MRI. It generates varying magnetic fields that enable precise slice selection by altering the Larmor frequency across the patient. Additionally, these gradients spatially encode the MR signal by creating frequency and phase shifts, which are essential for reconstructing a detailed image. Therefore, all listed options are primary goals of the gradient subsystem.

Question 39: A 2D spin-echo scan uses TR = 500 ms, a 256 (phase) x 256 (frequency) matrix, and 2 NEX. What is the approximate scan time?

8 minutes 32 seconds
1 minute 4 seconds
4 minutes 16 seconds (Correct answer)
2 minutes 8 seconds

Correct answer: 4 minutes 16 seconds

2D scan time = TR x number of phase-encoding steps x NEX. Here that is 0.5 s x 256 x 2 = 256 s, or about 4 minutes 16 seconds. The frequency matrix does not affect scan time.

Question 40: Pulsatile flow artifact from a vessel typically appears as ghost images displaced in which direction?

Phase-encoding direction (Correct answer)
Both frequency and phase directions equally
Slice-selection direction
Frequency-encoding direction

Correct answer: Phase-encoding direction

Pulsatile flow ghosts appear in the phase-encoding direction because pulsatile variations in spin phase occur between TR intervals during phase-encode data collection.

Question 41: Which MRI technique uses the difference in signal between in-phase and opposed-phase images to detect intravoxel fat within a lesion?

MR spectroscopy
STIR fat suppression
Diffusion-weighted imaging
Chemical shift imaging (Dixon technique) (Correct answer)

Correct answer: Chemical shift imaging (Dixon technique)

Chemical shift imaging exploits the precession frequency difference between fat and water; signal drop on opposed-phase images indicates intravoxel fat content.

Question 42: What is the effect of reducing the number of phase-encoding steps while keeping FOV and frequency steps constant?

Through-plane resolution is affected
Frequency-direction resolution decreases
SNR improves and scan time increases
Scan time decreases and phase-direction spatial resolution decreases (Correct answer)

Correct answer: Scan time decreases and phase-direction spatial resolution decreases

Fewer phase-encoding steps means less time to fill k-space (shorter scan) but larger voxels in the phase direction, reducing spatial resolution in that dimension.

Question 43: On diffusion-weighted MRI (DWI), an acute ischemic infarct typically shows:

Low signal on both DWI and ADC maps
Low signal on DWI and high ADC values
High signal on DWI and low ADC values (Correct answer)
High signal on DWI and high ADC values

Correct answer: High signal on DWI and low ADC values

Cytotoxic edema in acute infarction restricts water diffusion, producing high signal on DWI and low apparent diffusion coefficient (ADC) values.

Question 44: A patient is claustrophobic and anxious before their MRI. Which non-pharmacological intervention is most appropriate first?

Use a stronger magnetic field to shorten scan time
Explain the procedure, offer a patient communication system, and consider feet-first entry (Correct answer)
Immediately administer IV sedation
Refuse the exam and reschedule

Correct answer: Explain the procedure, offer a patient communication system, and consider feet-first entry

Thorough patient education, reassurance, mirror/prism glasses, music headphones, and entering the bore feet-first can significantly reduce claustrophobia before pharmacological intervention.

Question 45: Chemical shift artifact of the first kind occurs at interfaces between fat and water and manifests as:

Image wrap-around from the opposite side
Signal voids around metallic implants
Zebra-stripe banding artifact
A bright band and a dark band at the fat-water interface in the frequency-encoding direction (Correct answer)

Correct answer: A bright band and a dark band at the fat-water interface in the frequency-encoding direction

First-kind chemical shift artifact creates a bright rim on one side and a dark void on the other side at fat-water interfaces in the frequency-encoding direction due to the 3.5 ppm resonance frequency difference.

Question 46: Which of the following best describes the 'magic angle' artifact and at what angle it occurs?

T2 darkening of tendons at 45° to B0
Susceptibility dropout at 45° to B0
Chemical shift banding in fat at 55°
Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0 (Correct answer)

Correct answer: Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0

When ordered collagen fibers (tendons, ligaments) are oriented at ~55° to B0, dipole-dipole interactions average to zero, artifactually increasing signal on short TE sequences.

Question 47: Which parameter directly controls the degree of T2 weighting in a spin echo sequence?

Bandwidth
Flip angle
TE (echo time) (Correct answer)
TR (repetition time)

Correct answer: TE (echo time)

TE determines how long transverse magnetization decays before sampling; a longer TE allows more T2 decay, increasing T2 contrast.

Question 48: What determines the slice thickness in a standard 2D MRI acquisition?

The number of phase-encoding steps
The field of view and matrix size
The repetition time and echo time
The bandwidth of the RF pulse and the slope of the slice-select gradient (Correct answer)

Correct answer: The bandwidth of the RF pulse and the slope of the slice-select gradient

Slice thickness = RF bandwidth / (gyromagnetic ratio × gradient strength); a wider RF bandwidth or shallower gradient yields a thicker slice.

Question 49: Which labeling term indicates that an item has been tested and poses no known hazards in ALL MRI environments?

MR Safe (Correct answer)
MR Conditional
MR Compatible
MR Approved

Correct answer: MR Safe

The ASTM 'MR Safe' label means the item poses no known hazards in all MRI environments and is made of non-conductive, non-magnetic, non-RF-reactive materials.

Question 50: Which parameter, when increased, will most directly improve the signal-to-noise ratio (SNR) in an MRI image?

Increasing the bandwidth
Increasing the echo train length (ETL)
Decreasing the field of view (FOV)
Increasing the number of excitations (NEX/NSA) (Correct answer)

Correct answer: Increasing the number of excitations (NEX/NSA)

Increasing NEX/NSA averages more signal acquisitions, which reduces noise and improves SNR proportional to the square root of the number of averages.

Question 51: The standard dose of a non-specific extracellular GBCA for most MRI examinations is:

0.01 mmol/kg
0.3 mmol/kg
0.1 mmol/kg (Correct answer)
0.05 mmol/kg

Correct answer: 0.1 mmol/kg

The standard dose for most extracellular GBCAs is 0.1 mmol/kg body weight, which provides adequate contrast enhancement for most clinical applications.

Question 52: Which MRI sequence is most commonly used for evaluating liver lesions using T2 contrast with heavy T2 weighting for the bile ducts?

T1 in-phase/opposed-phase
DWI b1000
STIR of the abdomen
MRCP (heavily T2-weighted 3D or thick-slab) (Correct answer)

Correct answer: MRCP (heavily T2-weighted 3D or thick-slab)

MRCP uses heavily T2-weighted sequences to make bile and pancreatic fluid appear bright, providing a non-invasive map of the biliary and pancreatic ductal system.

Question 53: Echo planar imaging (EPI) is used in which MRI techniques due to its extremely fast acquisition speed?

Conventional T1 spin echo and MRCP
STIR and inversion recovery sequences
DWI, fMRI, and perfusion imaging (Correct answer)
MR arthrography and spectroscopy

Correct answer: DWI, fMRI, and perfusion imaging

EPI acquires an entire k-space in a single excitation, enabling the speed needed for diffusion-weighted imaging, fMRI BOLD imaging, and dynamic perfusion studies.

Question 54: Bilateral symmetric T2 hyperintensity in the basal ganglia of a child is most associated with which condition?

Acute ischemic stroke
Glioblastoma multiforme
Wilson's disease or metabolic disorder (Correct answer)
Multiple sclerosis

Correct answer: Wilson's disease or metabolic disorder

Bilateral symmetric basal ganglia T2 signal abnormality in a child raises concern for metabolic disorders such as Wilson's disease, mitochondrial disease, or toxic encephalopathy.

Question 55: Most superconducting magnets have a (horizontal or vertical) magnetiic field and are of the design type __.

Resistive magnet
Permanent magnet
Selenoid magnet (Correct answer)
Superconducting

Correct answer: Selenoid magnet

Most high-field superconducting MRI magnets are designed as solenoid magnets. In this configuration, the superconducting wire coils are arranged to create a strong, uniform magnetic field that runs horizontally through the bore of the scanner. This solenoid design is highly efficient for generating the powerful and homogeneous fields required for advanced MRI imaging.

Question 56: Gadolinium contrast extravasation at the IV injection site is classified as which type of adverse event?

Vascular reaction
Local injection site reaction (extravasation) (Correct answer)
Non-allergic physiologic reaction
Allergic-like reaction

Correct answer: Local injection site reaction (extravasation)

Extravasation occurs when contrast leaks from the vein into surrounding tissue; it is a local injection site reaction, not a systemic allergic event.

Question 57: Which ACR safety zone is the MR scanner room itself?

Zone III
Zone II
Zone IV (Correct answer)
Zone I

Correct answer: Zone IV

Zone IV is the magnet room and must be clearly marked and accessible only under direct MR personnel supervision.

Question 58: Which artifact arises when signal from outside the FOV wraps around to the opposite side of the image?

Chemical shift artifact
Susceptibility artifact
Aliasing (wrap-around) artifact (Correct answer)
Gibbs ringing artifact

Correct answer: Aliasing (wrap-around) artifact

Aliasing occurs in the phase-encode direction when anatomy outside the FOV is undersampled, causing it to appear on the opposite side.

Question 59: Partial Fourier (half-NEX) imaging cuts scan time by acquiring a little more than half of k-space. What property of k-space makes this possible?

Chemical shift
Gradient linearity
Conjugate (Hermitian) symmetry (Correct answer)
T2* decay

Correct answer: Conjugate (Hermitian) symmetry

In theory k-space is conjugate-symmetric: data in one half mirrors the data in the opposite half. So a little more than half can be acquired and the rest calculated. This saves time but lowers SNR, because less data is actually sampled.

Question 60: Magnets that use liquid helium or cryogen to cool the wires after applying direct current to a coil of wire.

Permanent magnet
Resistive magnet
Selenoid magnet
Superconducting (Correct answer)

Correct answer: Superconducting

Superconducting magnets utilize special alloys that, when cooled to extremely low temperatures (near absolute zero) using cryogens like liquid helium, lose all electrical resistance. This allows a large current to flow indefinitely without power, creating very strong and stable magnetic fields. These magnets are essential for high-field MRI systems, typically operating at 1.5 Tesla and above.

Question 61: Which MRI finding is characteristic of a benign rotator cuff tear involving a full-thickness supraspinatus tendon rupture?

Low signal on all sequences through the tendon
Low T2 signal with thickening of the tendon
Fluid signal gap (T2 bright) extending through the full thickness of the tendon (Correct answer)
T1 bright signal in the tendon

Correct answer: Fluid signal gap (T2 bright) extending through the full thickness of the tendon

A full-thickness tear shows fluid (T2 hyperintense) extending completely through the tendon from bursal to articular surface.

Question 62: Fast spin-echo (FSE/TSE) sequences acquire multiple lines of k-space per TR using which approach?

Rapidly toggling the frequency-encoding gradient
A single 90° pulse followed by multiple 180° refocusing pulses (echo train) (Correct answer)
Multiple 90° pulses with a single 180° refocusing pulse
Using a series of partial flip-angle pulses

Correct answer: A single 90° pulse followed by multiple 180° refocusing pulses (echo train)

FSE uses an echo train (RARE principle): after a 90° excitation, a series of 180° pulses generates multiple spin echoes, each phase-encoded differently, filling multiple k-space lines per TR.

Question 63: What score does ARRT use to determine passing on the MRI registry examination?

A raw score of 75%
A scaled score of 75 out of 99
A norm-referenced score based on the current testing cohort
A criterion-referenced passing standard set by content experts (Correct answer)

Correct answer: A criterion-referenced passing standard set by content experts

ARRT uses a criterion-referenced passing standard established by a panel of content experts, not a simple percentage or norm-based cut score.

Question 64: A candidate applying for the ARRT MRI registry via the post-primary pathway must hold a primary ARRT certification in which of the following disciplines?

Medical assisting
Medical dosimetry
Radiography, nuclear medicine, radiation therapy, or sonography (Correct answer)
Dental radiology

Correct answer: Radiography, nuclear medicine, radiation therapy, or sonography

The post-primary pathway requires a current, active ARRT primary credential in an approved imaging or therapy discipline.

Question 65: When imaging the lumbar spine, which position best opens the intervertebral foramina and reduces lumbar lordosis for improved visualization?

Supine with legs elevated on a cushion (knees and hips flexed) (Correct answer)
Lateral decubitus
Prone with pillow under abdomen
Prone with legs extended

Correct answer: Supine with legs elevated on a cushion (knees and hips flexed)

Flexing the hips and knees while supine flattens lumbar lordosis, opens intervertebral foramina, and improves disc and nerve root visualization.

Question 66: Following an RF burst, protons will

As per T2*, dephase in accordance with T1 and then recover along B0.
As instructed by T1, recover along B0, and then dephase as instructed by T2*.
As per T2*, recover along B0, and thereafter dephase in accordance with T1.
Dephase in accordance with T2*, then recover in accordance with T1 along B0. (Correct answer)

Correct answer: Dephase in accordance with T2*, then recover in accordance with T1 along B0.

Immediately following an RF burst, the excited protons begin to lose their phase coherence, causing the transverse magnetization to decay. This dephasing is governed by T2* relaxation, which includes both intrinsic molecular interactions and static magnetic field inhomogeneities. Simultaneously, the longitudinal magnetization, which was tipped away from B0, begins to recover along the B0 field, a process governed by T1 relaxation.

Question 67: What document must candidates agree to when submitting an ARRT MRI registry application?

ASRT Scope of Practice
JRCERT Accreditation Standards
ACR Practice Parameter for MRI
ARRT Standards of Ethics (Correct answer)

Correct answer: ARRT Standards of Ethics

All ARRT applicants must attest to adhering to the ARRT Standards of Ethics as a condition of application.

Question 68: For MRI of the internal auditory canals (IACs), which imaging plane is most commonly used as the primary plane?

Axial (Correct answer)
Oblique coronal
Sagittal oblique
Coronal

Correct answer: Axial

Axial high-resolution images are the primary plane for IAC MRI because they show the full length of CN VII and CN VIII within the canal.

Question 69: Magnetization transfer contrast (MTC) in MRI is based on the exchange of magnetization between which two proton pools?

Intracellular and extracellular water
Free water protons and bound macromolecular protons (Correct answer)
Fat protons and water protons
Arterial and venous blood

Correct answer: Free water protons and bound macromolecular protons

MTC involves saturation of bound macromolecular protons, which transfer their saturation to free water protons, reducing signal in tissues with high macromolecular content.

Question 70: What happens to image contrast when the echo time (TE) is increased in a T2-weighted sequence?

Tissues appear uniformly bright
T2 contrast increases as tissues with short T2 decay faster (Correct answer)
SNR improves due to longer signal collection
T1 contrast increases

Correct answer: T2 contrast increases as tissues with short T2 decay faster

Longer TE allows more T2 decay to occur, so tissues with short T2 lose signal faster and appear darker, enhancing T2 contrast between tissues.

Question 71: Gibbs (truncation) artifact is caused by:

Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces (Correct answer)
Patient motion during scanning
Aliasing from a FOV smaller than the patient
Field inhomogeneity near air-tissue interfaces

Correct answer: Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces

Gibbs artifact arises from the Fourier series representation of sharp edges when high spatial-frequency k-space data is truncated, producing ringing lines parallel to the interface.

Question 72: Which coil configuration is used to image the entire spine in a single acquisition with uniform SNR?

Head and neck coil alone
Phased-array spine coil spanning cervical, thoracic, and lumbar regions (Correct answer)
Body transmit/receive coil only
Single surface coil placed at the lumbar spine

Correct answer: Phased-array spine coil spanning cervical, thoracic, and lumbar regions

A multi-element phased-array spine coil allows large FOV imaging with high SNR throughout the cervical, thoracic, and lumbar spine in a single or stitched acquisition.

Question 73: For a contrast-enhanced MRA of the aorta, the bolus tracking technique monitors contrast arrival in which vessel to trigger the 3D acquisition?

Superior mesenteric artery
Right atrium
Femoral artery
Abdominal aorta or descending thoracic aorta at the level of interest (Correct answer)

Correct answer: Abdominal aorta or descending thoracic aorta at the level of interest

A monitoring slice is placed at the aorta at the target level; when the contrast bolus arrives (signal threshold), the 3D acquisition is automatically triggered.

Question 74: What is the relationship between voxel size and SNR in MRI?

Smaller voxels produce higher SNR
Voxel size has no effect on SNR
Larger voxels produce higher SNR (Correct answer)
SNR decreases as voxel volume doubles

Correct answer: Larger voxels produce higher SNR

Larger voxels contain more protons contributing signal, increasing SNR, though at the cost of spatial resolution.

Question 75: The 'magic angle' artifact in MRI tendons occurs at approximately what angle relative to the main magnetic field?

45°
15°
55° (Correct answer)
30°

Correct answer: 55°

Magic angle artifact occurs when a tendon is oriented at approximately 55° (the magic angle) to B0, causing artificial T1/PD signal increase that can mimic pathology.

Question 76: Which of the following best describes the purpose of placing the frequency-encoding gradient in the anterior-posterior direction for spine MRI?

To shorten scan time
To reduce phase wrap (aliasing) from anterior abdominal structures (Correct answer)
To increase SNR
To reduce susceptibility artifact

Correct answer: To reduce phase wrap (aliasing) from anterior abdominal structures

Placing frequency encoding AP moves phase wrap artifact (aliasing) to the AP direction, preventing anterior abdominal fat from wrapping onto the spine.

Question 77: A patient has a medication patch with a metallic foil backing. What is the main safety concern?

Reduced absorption of the medication
The patch being pulled into the bore
RF heating that can burn the skin (Correct answer)
Image distortion only

Correct answer: RF heating that can burn the skin

Metallic backing can heat during RF transmission, so these patches are usually removed before scanning with the prescriber's approval.

Question 78: Which inversion recovery technique is used to suppress fat signal in musculoskeletal MRI?

MPRAGE
STIR (Short TI Inversion Recovery) (Correct answer)
FLAIR
VIBE

Correct answer: STIR (Short TI Inversion Recovery)

STIR uses a short inversion time timed to null the longitudinal magnetization of fat, suppressing fat signal uniformly regardless of field inhomogeneity.

Question 79: Parallel imaging techniques such as GRAPPA and SENSE reduce scan time by:

Increasing the magnetic field strength
Eliminating the need for radiofrequency pulses
Applying stronger gradient pulses
Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps (Correct answer)

Correct answer: Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps

Parallel imaging exploits spatial sensitivity information from multiple coil elements to skip phase encoding lines, reconstructing the full image and reducing acquisition time.

Question 80: Which MRI technique encodes functional brain activity by detecting changes in blood oxygenation level?

MR spectroscopy (MRS)
Arterial spin labeling (ASL)
Diffusion tensor imaging (DTI)
Blood oxygen level-dependent (BOLD) fMRI (Correct answer)

Correct answer: Blood oxygen level-dependent (BOLD) fMRI

BOLD fMRI detects regional neural activity via the magnetic susceptibility difference between oxyhemoglobin and deoxyhemoglobin, providing maps of brain activation.

Question 81: Which MRI technique measures cerebral blood flow and volume without contrast injection, using arterial water protons as an endogenous tracer?

Phase contrast MRI
Dynamic susceptibility contrast (DSC) MRI
Arterial spin labeling (ASL) (Correct answer)
BOLD fMRI

Correct answer: Arterial spin labeling (ASL)

ASL uses RF pulses to magnetically label (invert) arterial blood water protons proximal to the imaging slab; labeled images are subtracted from control images to quantify cerebral perfusion.

Question 82: For pituitary gland MRI, which plane is considered the primary imaging plane?

Axial
Sagittal
Coronal (Correct answer)
Oblique axial

Correct answer: Coronal

Coronal thin-slice images are the primary plane for pituitary imaging because they best demonstrate lateral extension, cavernous sinus invasion, and microadenomas.

Question 83: During an MRI exam, a patient begins experiencing intense burning sensations on their skin near monitoring cables. What is the most likely cause?

Quench event beginning
Gradient-induced peripheral nerve stimulation
RF-induced heating from looped or coiled cables (Correct answer)
SAR limit exceeded

Correct answer: RF-induced heating from looped or coiled cables

Looped or coiled cables act as antennas and can develop high RF-induced currents causing thermal burns on the skin.

Question 84: One forms a spin echo through

changing the path of a proton using a radiofrequency pulse (Correct answer)
Turning B0 in the opposite direction
Using a gradient of a negative magnetic field

Correct answer: changing the path of a proton using a radiofrequency pulse

A spin echo is formed by applying a 180-degree radiofrequency (RF) pulse after an initial 90-degree RF excitation pulse. This 180-degree pulse effectively 'flips' the spins, causing them to rephase and produce a detectable echo signal. By reversing the effects of static magnetic field inhomogeneities, the 180-degree pulse allows for the recovery of signal that would otherwise be lost due to T2* dephasing.

Question 85: On brain MRI, the hippocampus is best evaluated for atrophy (as in Alzheimer's disease) on which plane?

Sagittal only
Axial only
Oblique axial
Coronal, especially perpendicular to the long axis of the hippocampus (Correct answer)

Correct answer: Coronal, especially perpendicular to the long axis of the hippocampus

Coronal T1-weighted images perpendicular to the long axis of the hippocampus provide the best visualization of hippocampal volume and atrophy.

Question 86: FLAIR (Fluid-Attenuated Inversion Recovery) suppresses which signal and is most useful for detecting:

Blood signal; hemorrhage
CSF signal; periventricular and cortical lesions (Correct answer)
Muscle signal; soft tissue tumors
Fat signal; bone marrow edema

Correct answer: CSF signal; periventricular and cortical lesions

FLAIR uses an inversion pulse timed to null CSF, making periventricular lesions and cortical pathology (MS plaques, subarachnoid hemorrhage) visible against suppressed fluid.

Question 87: A patient reports having a cardiac pacemaker. What is the standard MRI safety classification for most older pacemakers?

MR Unsafe (Correct answer)
MR Compatible
MR Safe
MR Conditional

Correct answer: MR Unsafe

Most older pacemakers are classified MR Unsafe because the magnetic field can interfere with device function or cause heating.

Question 88: A patient develops nausea and vomiting during IV gadolinium infusion. The most appropriate immediate action is to:

Administer epinephrine immediately
Continue the infusion as nausea is expected
Stop the infusion, assess the patient, and administer antiemetic if needed while monitoring for escalation (Correct answer)
Increase infusion rate to complete dosing faster

Correct answer: Stop the infusion, assess the patient, and administer antiemetic if needed while monitoring for escalation

Nausea and vomiting may be physiologic reactions to GBCA; the injection should be stopped, the patient assessed, symptoms treated, and the reaction monitored for potential escalation to a more serious event.

Question 89: For a brain MRI, which standard plane best demonstrates the corpus callosum in its entirety?

Oblique
Coronal
Axial
Sagittal (Correct answer)

Correct answer: Sagittal

The midsagittal plane shows the entire corpus callosum from the genu to the splenium as a continuous C-shaped structure.

Question 90: Which MRI screening form section is most critical for identifying implanted devices that may be MR Unsafe?

Surgical history section
Allergies section
Implants and devices section (Correct answer)
Medication list section

Correct answer: Implants and devices section

The implants and devices section identifies items such as pacemakers, cochlear implants, and aneurysm clips that may be MR Unsafe.

Question 91: On MRI, cortical bone appears as which signal intensity on both T1 and T2 weighted images?

Low signal (signal void) (Correct answer)
Intermediate signal
High signal
Variable signal

Correct answer: Low signal (signal void)

Cortical bone has very few mobile protons and produces a signal void (low signal) on both T1 and T2 weighted MRI sequences.

Question 92: In MRI of the breast, a finding described as a 'rim-enhancing mass' on dynamic contrast imaging is most suspicious for:

Malignant lesion (Correct answer)
Simple cyst
Fat necrosis
Fibroadenoma

Correct answer: Malignant lesion

Rim enhancement of a breast mass, indicating peripheral enhancement with central necrosis, is a suspicious finding associated with malignancy.

Question 93: A metalworker reports possibly getting metal in his eye years ago but has no documentation. What is the most appropriate step before MRI?

Scan with a lower SAR setting
Proceed, since old fragments are always encapsulated
Get orbital radiographs to screen for a foreign body (Correct answer)
Ask him to keep his eyes closed during the scan

Correct answer: Get orbital radiographs to screen for a foreign body

Orbit radiographs are the standard way to screen for intraocular metal, which could move and cause blindness.

Question 94: Which of the following is the most effective method to reduce motion artifact from bowel peristalsis in abdominal MRI?

Use a larger FOV
Apply saturation bands inferior to the FOV
Increase TR
Administer an antiperistaltic agent such as glucagon (Correct answer)

Correct answer: Administer an antiperistaltic agent such as glucagon

IV or IM glucagon inhibits smooth muscle contraction (antiperistaltic effect), reducing bowel motion artifact during abdominal MRI acquisitions.

Question 95: Which of the following is a mandatory competency category that must be documented before a student can sit for the ARRT MRI registry?

Cardiac MRI stress testing
Head MRI without contrast (Correct answer)
MRI-guided biopsy procedures
MRI-compatible pacemaker implantation

Correct answer: Head MRI without contrast

Head MRI without contrast is among the required clinical competencies students must document as part of ARRT's clinical requirements.

Question 96: In a fast spin echo sequence, the effective TE is determined by which factor?

The average TE of all echoes in the train
The echo acquired when the central lines of k-space are filled (Correct answer)
The time of the first echo in the echo train
The echo spacing multiplied by the echo train length

Correct answer: The echo acquired when the central lines of k-space are filled

Image contrast comes mostly from the center of k-space, so the echo that fills the central lines sets the effective TE.

Question 97: Which structure in the knee joint is best evaluated with MRI and appears as a low-signal-intensity triangular structure?

Articular cartilage
Medial meniscus (Correct answer)
Patellar tendon
Anterior cruciate ligament

Correct answer: Medial meniscus

The medial meniscus is best visualized on MRI as a low-signal-intensity fibrocartilaginous triangular structure on coronal and sagittal images.

Question 98: The landmark for centering an MRI brain exam using a head coil is located at:

Top of the skull
Occiput
External auditory meatus
Nasion or bridge of the nose (Correct answer)

Correct answer: Nasion or bridge of the nose

The nasion (bridge of the nose) is the standard external landmark used to center the isocenter of the MRI system for brain imaging.

Question 99: To form a magnet field, wires are arranged side by side.

Resistive magnet
Selenoid magnet (Correct answer)
Permanent magnet
Superconducting

Correct answer: Selenoid magnet

A solenoid magnet is formed by coiling a wire into a cylindrical shape. When an electric current passes through this coiled wire, it generates a uniform magnetic field along the axis of the cylinder. This design is fundamental to many types of MRI magnets, particularly superconducting systems, where the solenoid configuration efficiently produces a strong, homogeneous field.

Question 100: What is the purpose of the radiofrequency (RF) pulse in an MRI sequence?

To increase static magnetic field strength
To suppress gradient coil noise
To tip net magnetization away from B0 (Correct answer)
To align hydrogen nuclei with each other

Correct answer: To tip net magnetization away from B0

The RF pulse at the Larmor frequency tips the net magnetization vector away from the longitudinal axis to induce signal.

Question 101: Which of the following best describes a blood-pool GBCA used in MR angiography?

It remains exclusively in the arterial system
It distributes only in hepatic tissue
It crosses the blood-brain barrier
It binds reversibly to albumin, prolonging intravascular residence time (Correct answer)

Correct answer: It binds reversibly to albumin, prolonging intravascular residence time

Blood-pool agents (e.g., gadofosveset) bind reversibly to albumin, extending their half-life in the vascular space and allowing steady-state MRA over a longer acquisition window.

Question 102: Which mathematical process converts the raw data stored in k-space into the MR image?

Bloch equation integration
Filtered back projection
Fourier transform (Correct answer)
Maximum intensity projection

Correct answer: Fourier transform

The MR signal is recorded as frequency and phase information in k-space. A 2D or 3D Fourier transform breaks that data into its component frequencies and maps them to pixel locations and intensities. Filtered back projection is mainly a CT method, and MIP is a post-processing display technique.

Question 103: Which patient condition requires consultation with the ordering physician regarding MRI safety due to potential risks during the first trimester?

Mild hypertension controlled with oral medication
Known pregnancy, especially first trimester (Correct answer)
Prior abdominal surgery more than 1 year ago
Known diabetes mellitus

Correct answer: Known pregnancy, especially first trimester

MRI in the first trimester is performed with caution; although no confirmed harm is established, ACR guidelines recommend physician consultation and clinical justification for first-trimester MRI.

Question 104: Under ARRT policy, which scenario would trigger an automatic ethics review before an MRI registry application is processed?

Candidate previously worked as a radiography aide
Candidate has a prior misdemeanor conviction on record (Correct answer)
Candidate has exceeded the CE deadline by one week
Candidate holds a second radiography credential

Correct answer: Candidate has a prior misdemeanor conviction on record

ARRT requires candidates with prior criminal history to undergo an ethics review to determine eligibility before the application proceeds.

Question 105: A patient with a metallic foreign body in the eye should be evaluated with which imaging modality BEFORE entering the MRI suite?

Ultrasound
Bone scan
CT scan (Correct answer)
PET scan

Correct answer: CT scan

A CT scan of the orbits is used to detect metallic ocular foreign bodies before MRI because ferromagnetic metal near the eye is a contraindication.

Question 106: Which breast MRI positioning protocol is standard for screening and diagnostic evaluation?

Lateral decubitus with the ipsilateral breast dependent
Supine with arms overhead
Prone with the breasts in a dedicated bilateral breast coil (Correct answer)
Upright in a dedicated open MRI

Correct answer: Prone with the breasts in a dedicated bilateral breast coil

Prone positioning with bilateral dedicated breast coils provides optimal tissue separation, bilateral coverage, and reproducible enhancement kinetics.

Question 107: Which property of hydrogen makes it the most commonly used nucleus in clinical MRI?

Absence of electron cloud interference
High natural abundance and large magnetic moment (Correct answer)
High atomic number and radioactivity
Low atomic mass and zero spin

Correct answer: High natural abundance and large magnetic moment

Hydrogen (¹H) is abundant in the body and has a large gyromagnetic ratio, producing strong MRI signals.

Question 108: Which GBCA is approved by the FDA as a liver-specific agent taken up by hepatocytes?

Gadoxetate disodium (Eovist/Primovist) (Correct answer)
Gadobutrol (Gadavist)
Gadopentetate dimeglumine (Magnevist)
Gadobenate dimeglumine (MultiHance)

Correct answer: Gadoxetate disodium (Eovist/Primovist)

Gadoxetate disodium (Eovist in the US, Primovist in Europe) is taken up by functioning hepatocytes via OATP transporters, providing hepatobiliary phase imaging for liver lesion characterization.

Question 109: Magnets formed of ferrous material found naturally or from blocks or slabs.

Permanent (Correct answer)
Superconducting
Selenoid
Reistive

Correct answer: Permanent

Permanent magnets are created from naturally occurring ferromagnetic materials or specially treated blocks of ferrous material. These magnets retain their magnetism without requiring an external power source. They produce a constant magnetic field and are typically utilized in low-field MRI systems, offering a simpler and less costly design.

Question 110: In MR imaging, the signal-to-noise ratio (SNR) improves with increasing field strength approximately as:

Linearly (proportional to B0) (Correct answer)
As the square of B0 (B0²)
As the square root of B0
SNR is independent of field strength

Correct answer: Linearly (proportional to B0)

SNR scales approximately linearly with B0 because both the equilibrium magnetization and the Larmor frequency (and thus the induced EMF) increase linearly with field strength.

Question 111: For temporomandibular joint (TMJ) MRI, images are obtained with the jaw in which two positions?

Supine and prone
Clenched and relaxed
Right lateral and left lateral
Open and closed mouth (Correct answer)

Correct answer: Open and closed mouth

TMJ MRI is performed with the mouth both open and closed to evaluate articular disc position and movement through the full range of condylar motion.

Question 112: Which artifact appears as parallel bright and dark bands in the phase-encoding direction when the FOV is too small and the patient extends beyond it?

Aliasing (wraparound) (Correct answer)
Chemical shift type 2
Susceptibility artifact
Gibbs ringing

Correct answer: Aliasing (wraparound)

When anatomy outside the FOV is phase-encoded, it aliases (wraps around) and appears as a superimposed copy on the opposite edge of the image, sometimes appearing as bands.

Question 113: Which phase-encoding direction choice can help reduce motion artifact from breathing in abdominal MRI?

Increase the number of slices
Orient phase encoding in the anterior-posterior direction to capture all motion
Use a larger FOV in the frequency direction
Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest (Correct answer)

Correct answer: Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest

Placing phase encoding in the right-left direction directs respiratory ghosting away from critical abdominal structures, reducing diagnostic interference.

Question 114: In which direction does the chemical shift type 2 (India ink) artifact appear at fat-water interfaces, and on which sequence type is it seen?

Both directions on EPI
In-phase direction on STIR sequences
Phase direction on gradient-echo sequences (Correct answer)
Frequency direction on spin-echo sequences

Correct answer: Phase direction on gradient-echo sequences

Chemical shift type 2 (India ink or black boundary artifact) occurs in gradient-echo sequences at fat-water voxel boundaries and appears as a dark rim at these interfaces.

Question 115: Which MR labeling symbol is a red circle with a diagonal line through it?

MR Compatible
MR Conditional
MR Safe
MR Unsafe (Correct answer)

Correct answer: MR Unsafe

Under ASTM F2503, MR Unsafe items are labeled with a red circle and a diagonal slash.

Question 116: Which ARRT resource provides the official list of examination content categories, subcategories, and approximate percentage weighting for the MRI registry exam?

ARRT Content Specifications document (Correct answer)
ASRT curriculum guide
JRCERT program outcomes report
ACR MRI practice parameters

Correct answer: ARRT Content Specifications document

The ARRT Content Specifications document is the authoritative blueprint that outlines all tested domains and their weightings for the MRI registry exam.

Question 117: MR spectroscopy (MRS) of the brain identifies metabolites by their distinct chemical shifts. Which metabolite is elevated in tumors with high cell density and membrane turnover?

Lactate
Choline (Cho) (Correct answer)
Creatine (Cr)
N-acetylaspartate (NAA)

Correct answer: Choline (Cho)

Choline is a marker of membrane synthesis and cellular turnover; elevated choline is characteristic of tumors, demyelination, and other high-proliferation states.

Question 118: When positioning a patient for a lumbar spine MRI, the technologist should place the patient in which position to reduce lumbar lordosis and improve image quality?

Lateral decubitus position
Prone with legs flat
Supine with knees flexed and supported by a foam wedge (Correct answer)
Seated upright

Correct answer: Supine with knees flexed and supported by a foam wedge

Flexing the knees with a foam wedge support flattens lumbar lordosis, reducing the curvature and aligning disc spaces parallel to axial slices for optimal visualization.

Question 119: In cardiac MRI, which sequence is used to assess myocardial viability and detect scar tissue?

First-pass perfusion with adenosine stress
True FISP cine imaging
Black-blood T2 STIR
Late gadolinium enhancement (LGE) with inversion recovery (Correct answer)

Correct answer: Late gadolinium enhancement (LGE) with inversion recovery

Late gadolinium enhancement (LGE) uses an inversion recovery sequence 10–15 minutes after GBCA injection; scarred myocardium retains gadolinium and appears bright against nulled normal myocardium.

Question 120: On a sagittal MRI of the cervical spine, the posterior longitudinal ligament appears as a thin structure along which surface of the vertebral bodies?

Anterior
Superior
Posterior (Correct answer)
Lateral

Correct answer: Posterior

The posterior longitudinal ligament runs along the posterior surfaces of the vertebral bodies inside the spinal canal, anterior to the thecal sac.

Question 121: A 'blooming' artifact on gradient echo (GRE) MRI is caused by which substance?

Hemosiderin or calcification (Correct answer)
Gadolinium contrast
Fat
Cerebrospinal fluid

Correct answer: Hemosiderin or calcification

Hemosiderin, calcium, and other susceptibility-inducing substances cause local field inhomogeneities that appear as signal loss blooming on GRE sequences.

Question 122: When should a technologist notify the supervising radiologist or radiologist immediately during an MRI exam?

When the patient requests a blanket
When the scan takes longer than expected
When any adverse reaction to contrast, change in patient condition, or safety concern arises (Correct answer)
When the patient completes the screening form

Correct answer: When any adverse reaction to contrast, change in patient condition, or safety concern arises

Any adverse reaction to contrast agent, unexpected change in patient condition (loss of consciousness, seizure, cardiac event), or safety concern requires immediate radiologist notification.

Question 123: Which section of the ARRT MRI content specifications covers pulse sequence selection and acquisition parameter optimization?

Physics and Instrumentation
Image Production (Correct answer)
Patient Care and Education
Procedures

Correct answer: Image Production

Image Production covers acquisition parameters, pulse sequences, and image quality optimization.

Question 124: Zipper artifact on an MRI image appears as a line of alternating bright and dark pixels across the image, most often caused by:

Coil coupling artifact
Patient movement
Gradient switching noise
External RF interference from inadequate shielding or open RF cage door (Correct answer)

Correct answer: External RF interference from inadequate shielding or open RF cage door

Zipper artifact is caused by external radiofrequency interference entering the scan room, typically due to an open waveguide, broken shielding, or improperly closed scanner room door.

Question 125: An MR Conditional implant's labeling specifies a B1+rms limit. What does this parameter describe?

The gradient slew rate
The time-averaged RF transmit field magnitude (Correct answer)
The static field strength allowed
The maximum spatial field gradient

Correct answer: The time-averaged RF transmit field magnitude

B1+rms is the root-mean-square RF transmit field, a more accurate measure of RF exposure for implants than SAR.

Question 126: What is a 'quench' in MRI terminology?

A gradient coil failure
A rapid increase in field strength
A sudden loss of superconductivity causing helium boil-off (Correct answer)
A patient motion artifact

Correct answer: A sudden loss of superconductivity causing helium boil-off

A quench occurs when the superconducting magnet loses its superconducting state, causing liquid helium to vaporize rapidly and potentially displacing oxygen in the room.

Question 127: A patient with a GFR of 45 mL/min/1.73m² requires a contrast-enhanced MRI. According to ACR guidelines, which GBCA group is preferred?

Group I linear ionic agents
Group II linear non-ionic agents
Contrast should be completely avoided
Group III macrocyclic agents (Correct answer)

Correct answer: Group III macrocyclic agents

The ACR recommends macrocyclic GBCAs (Group III) for patients with reduced renal function (GFR 30–60) due to their superior thermodynamic and kinetic stability.

Question 128: A T1 hyperintense (bright) lesion in the brain is most consistent with which finding?

Pure fluid-filled cyst
Vasogenic edema
Acute infarct
Subacute blood or fat-containing lesion (Correct answer)

Correct answer: Subacute blood or fat-containing lesion

T1 hyperintensity in the brain is classically associated with subacute hemorrhage (methemoglobin), fat, protein-rich fluid, or melanin.

Question 129: Which breathing technique is recommended for upper abdominal MRI (liver, pancreas) to minimize respiratory motion artifact?

Free breathing throughout all sequences
Continuous shallow breathing
Hyperventilation before each sequence
Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans (Correct answer)

Correct answer: Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans

Breath-hold sequences minimize diaphragmatic motion for dynamic contrast imaging; respiratory triggering or navigator gating is used for longer acquisitions that cannot be completed in a single breath-hold.

Question 130: EPI (echo planar imaging) sequences are particularly prone to which artifact caused by off-resonance spins accumulating phase during the long readout?

Susceptibility artifact only in GRE
Truncation artifact
Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion (Correct answer)
Magic angle artifact

Correct answer: Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion

EPI's long readout makes it sensitive to field inhomogeneity, causing geometric distortion along the phase-encode direction and N/2 ghosting from alternating echo phase inconsistencies.

Question 131: Which SAR limit (Specific Absorption Rate) is the FDA guideline for whole-body RF energy deposition in a 15-minute period for non-controlled conditions?

1.5 W/kg
3 W/kg
4 W/kg (Correct answer)
2 W/kg

Correct answer: 4 W/kg

The FDA guideline for whole-body average SAR under normal operating mode is 4 W/kg over any 15-minute period.

Question 132: Which MRI-compatible monitoring device is used to detect heart rate and trigger cardiac-gated sequences?

MR-conditional ECG with carbon or fiber-optic leads free of conductive loops (Correct answer)
Blood pressure cuff inflation timing
Finger-clip optical pulse oximeter (used for cardiac gating)
Standard hospital ECG with adhesive electrodes

Correct answer: MR-conditional ECG with carbon or fiber-optic leads free of conductive loops

MR-conditional ECG systems with non-conductive or carbon fiber leads detect the R-wave for cardiac gating without creating conductive loops that could cause burns.

Question 133: What differentiates T2 from T2* is

The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, or T2*, is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2. (Correct answer)
T2* is the product of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, which is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, or T2*.

Correct answer: The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2.

T2 relaxation describes the decay of transverse magnetization due to intrinsic molecular interactions and microscopic magnetic field inhomogeneities. T2* relaxation, however, encompasses both these intrinsic T2 effects and additional macroscopic static magnetic field inhomogeneities inherent to the scanner and patient. Therefore, T2* is always shorter than or equal to T2, as it accounts for more dephasing factors.

Question 134: A pregnant MRI technologist should follow which guideline regarding working in the MRI suite?

Wear a lead apron to reduce MRI exposure
Take a leave of absence immediately upon learning of pregnancy
Avoid all scanner rooms during pregnancy
Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure (Correct answer)

Correct answer: Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure

Current guidelines suggest limiting time within the bore and active scanner room primarily in the first trimester; there is no requirement to cease work entirely.

Question 135: Diffusion-weighted imaging (DWI) measures the random Brownian motion of water molecules. Restricted diffusion (e.g., in acute stroke) appears as:

High signal on DWI, high ADC
Low signal on DWI, high ADC
Low signal on DWI, low ADC
High signal on DWI, low ADC (Correct answer)

Correct answer: High signal on DWI, low ADC

In acute ischemia, cytotoxic edema restricts water movement; restricted diffusion shows high signal on DWI (b=1000) and low signal on ADC map (low diffusivity).

Question 136: Which of the following is a documented risk of MRI during the first trimester of pregnancy?

Acoustic noise damage to fetal hearing
Gadolinium retention in fetal tissue
All of the above except ionizing radiation (Correct answer)
Ionizing radiation exposure

Correct answer: All of the above except ionizing radiation

MRI does not use ionizing radiation, but first-trimester risks include acoustic noise and potential gadolinium retention; non-contrast scanning is preferred.

Question 137: Which MRI sequence is most sensitive for detecting early bone marrow edema in stress fractures?

GRE in-phase
Proton density without fat saturation
T1-weighted SE
STIR or fat-saturated T2 (Correct answer)

Correct answer: STIR or fat-saturated T2

STIR and fat-saturated T2 sequences suppress the bright fat signal of normal marrow, making the high-signal edema of stress fractures conspicuous.

Question 138: What is the purpose of applying a saturation band in MRI?

To increase SNR from the target anatomy
To improve spatial resolution in the phase direction
To shorten the overall scan time
To suppress signal from specified tissue or flowing blood to reduce artifacts (Correct answer)

Correct answer: To suppress signal from specified tissue or flowing blood to reduce artifacts

Saturation bands apply an RF pulse to a defined region, nulling its magnetization so it contributes no signal, which suppresses motion or flow-related artifacts.

Question 139: Cross-excitation (cross-talk) artifact in multislice MRI occurs because of:

Imperfect slice profiles causing RF excitation of adjacent slices (Correct answer)
Coil sensitivity overlap between two adjacent coil elements
Patient breathing between slice acquisitions
Gradient switching between adjacent slices

Correct answer: Imperfect slice profiles causing RF excitation of adjacent slices

Real RF pulses have imperfect rectangular profiles; the tails of adjacent slice profiles overlap, causing partial saturation of neighboring slices — reduced by interleaved acquisition or adding gaps.

Question 140: What is the main biological risk associated with rapidly switching gradient magnetic fields during an MRI scan?

Radiofrequency burns
Peripheral nerve stimulation (Correct answer)
Acoustic damage
Hypothermia

Correct answer: Peripheral nerve stimulation

Rapidly switching gradients can induce electrical currents in body tissue, causing peripheral nerve stimulation (PNS).

Question 141: What is the mechanism of action of gadolinium-based contrast agents (GBCAs) in MRI?

They increase T2 relaxation time, increasing signal on T2-weighted images
They directly emit radio waves that increase signal
They block radiofrequency pulses to create contrast
They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images (Correct answer)

Correct answer: They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images

Gadolinium shortens the T1 relaxation time of surrounding water protons through dipole-dipole interactions, causing increased signal intensity on T1-weighted sequences.

Question 142: A small bandwidth makes _slices possible.

Dicker
Slimmer (Correct answer)

Correct answer: Slimmer

In MRI, the slice selection gradient, in conjunction with the radiofrequency (RF) pulse, determines the slice thickness. A smaller receiver bandwidth means that a narrower range of frequencies is sampled. This corresponds to a smaller range of magnetic field strengths along the slice selection gradient, resulting in the selection of a thinner, or 'slimmer,' slice.

Question 143: The magnetic field's intensity is changed by this gradient coil from right to left.

Z
X (Correct answer)
Y

Correct answer: X

In a standard MRI coordinate system, the X-axis typically corresponds to the right-to-left (or left-to-right) direction across the patient. The X-gradient coil is engineered to produce a linear change in the magnetic field strength along this X-axis. This gradient is primarily used for spatial encoding, particularly for frequency encoding, in the right-to-left dimension.

Question 144: For MRI of the shoulder, the patient should be positioned with the arm in which orientation to best center the glenohumeral joint?

Arm in full internal rotation only
Arm elevated above the head
Arm at the side in neutral or slight external rotation, shoulder centered in the coil (Correct answer)
Arm crossed over the chest

Correct answer: Arm at the side in neutral or slight external rotation, shoulder centered in the coil

Positioning the shoulder with the arm at the side in neutral or slight external rotation and centering the glenohumeral joint within the dedicated shoulder coil optimizes image quality.

Question 145: Which classification of GBCAs carries the LOWEST risk for NSF based on ACR guidance?

Group II (linear non-ionic)
Group III (macrocyclic) (Correct answer)
Group I (linear ionic)
All GBCAs carry equal NSF risk

Correct answer: Group III (macrocyclic)

Macrocyclic GBCAs (Group III) have a more stable cage-like structure that resists transmetallation and are associated with the lowest NSF risk.

Question 146: Which anatomical landmark is used to prescribe the standard axial plane for brain MRI?

Hard palate line
Orbitomeatal baseline
Frankfurt plane
Anterior commissure–posterior commissure (AC-PC) line (Correct answer)

Correct answer: Anterior commissure–posterior commissure (AC-PC) line

Axial brain MRI slices are typically aligned parallel to the AC-PC line for standardized anatomical coverage and comparison.

Question 147: By adding more loops and circuitry, these coils increase the efficiency with which the MR signal is induced in the coil and raise SNR by about 40% when compared to coils of the same size.

Helmholtz pair
Phased array
Vertical
Quadrature (Correct answer)

Correct answer: Quadrature

Quadrature coils (or circularly polarized coils) utilize two receiver coils oriented 90 degrees to each other. By combining the signals from both coils, they can detect the rotating component of the MR signal more efficiently. This design leads to a theoretical 41% increase in signal-to-noise ratio (SNR) compared to a single linear coil of the same size, improving image quality.

Question 148: In dynamic contrast-enhanced (DCE) MRI of the breast, which kinetic enhancement curve pattern is most concerning for malignancy?

No enhancement
Persistent (type I)
Washout (type III) (Correct answer)
Plateau (type II)

Correct answer: Washout (type III)

A washout (type III) kinetic curve — rapid initial enhancement followed by signal decrease — is most suspicious for malignancy due to arteriovenous shunting in tumor neovasculature.

Question 149: IV line tubing and monitoring cables used inside the MRI suite must be:

Standard clinical-grade equipment from any hospital supply
Removed prior to scanning and replaced after
Made of stainless steel only
MR-conditional equipment specifically rated for use in the magnetic field (Correct answer)

Correct answer: MR-conditional equipment specifically rated for use in the magnetic field

All equipment used within the MRI environment must be labeled MR-conditional or MR Safe to prevent projectile events, burns, or device malfunction.

Question 150: In the ACR zone system, who is responsible for controlling access to Zone III?

MR-trained non-MR personnel
Any hospital staff with ID badge
Level 2 MR personnel (Correct answer)
Radiology technologists only

Correct answer: Level 2 MR personnel

Zone III access must be controlled by Level 2 MR personnel (those with full MR safety training) to prevent non-screened individuals from entering.

Question 151: What is contrast-to-noise ratio (CNR) in MRI and why is it important?

The ratio of gadolinium dose to body weight
The ratio of TR to TE for optimal contrast
The number of phase encodes used to improve tissue differentiation
The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue (Correct answer)

Correct answer: The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue

CNR is the SNR difference between adjacent tissues; high CNR is essential for detecting lesions because it reflects how well two tissues can be discriminated from each other.

Question 152: The anterior and posterior horns of the lateral ventricles are best evaluated for periventricular leukomalacia (PVL) on which MRI plane?

Axial and coronal (Correct answer)
Oblique
Sagittal only
Coronal only

Correct answer: Axial and coronal

Axial and coronal planes together best demonstrate periventricular T2 signal changes and volume loss around the lateral ventricular horns in PVL.

Question 153: Which of the following best describes the concept of signal-to-noise ratio (SNR) in MRI?

The ratio of TE to TR
The ratio of mean signal intensity in a region of interest to the standard deviation of background noise (Correct answer)
The number of signal averages divided by scan time
The difference in signal between two adjacent tissues

Correct answer: The ratio of mean signal intensity in a region of interest to the standard deviation of background noise

SNR is quantitatively defined as the mean signal from a region of interest divided by the standard deviation of noise measured in a background air region.

Question 154: What term describes an object becoming a high-speed projectile when brought near a strong MRI magnetic field?

Susceptibility effect
Quenching effect
Missile effect (Correct answer)
Gradient artifact

Correct answer: Missile effect

The missile effect (or projectile effect) occurs when ferromagnetic objects are rapidly accelerated toward the bore by the strong static magnetic field.

Question 155: Which MRI zone is defined as the area containing the MRI scanner itself where the static magnetic field is always present?

Zone II
Zone IV (Correct answer)
Zone III
Zone I

Correct answer: Zone IV

Zone IV is the MRI scanner room where the magnet is always on and unrestricted ferromagnetic items pose immediate danger.

Question 156: Which MRI sequence is the standard for evaluating the internal structure of bone marrow and is most sensitive to marrow infiltration or edema?

T2*-weighted gradient echo
T1-weighted spin-echo
Proton density without fat suppression
STIR or fat-suppressed T2-weighted FSE (Correct answer)

Correct answer: STIR or fat-suppressed T2-weighted FSE

STIR and fat-suppressed T2 sequences null normal fatty marrow signal, making pathological edema, infiltration, or tumor stand out as high signal against the nulled fat background.

Question 157: Magnetization transfer (MT) contrast in MRI works by selectively saturating which proton pool?

Bound protons in macromolecules (semisolid pool), which transfers saturation to free water (Correct answer)
Free water protons in tissue
Intracellular sodium protons
Fat protons at 3.5 ppm

Correct answer: Bound protons in macromolecules (semisolid pool), which transfers saturation to free water

An off-resonance RF pulse saturates the restricted macromolecular proton pool; saturation is transferred to free water through magnetization exchange, reducing the water signal proportional to MT ratio.

Question 158: Why does an ECG tracing inside the magnet often show an elevated T wave?

Electrode polarization from contrast
RF heating of the myocardium
Gradient-induced arrhythmia
The magnetohydrodynamic effect of blood flowing in the static field (Correct answer)

Correct answer: The magnetohydrodynamic effect of blood flowing in the static field

Ionic blood moving through the static field creates a voltage that adds to the ECG, mostly during the T wave.

Question 159: A technologist increases slice thickness from 3 mm to 6 mm. What is the expected change in image quality?

Both SNR and spatial resolution improve
No change occurs because FOV is unchanged
SNR improves but through-plane resolution decreases (Correct answer)
SNR decreases and spatial resolution improves

Correct answer: SNR improves but through-plane resolution decreases

Thicker slices contain more protons and generate more signal, improving SNR, but fine anatomical detail in the through-plane direction is reduced.

Question 160: The corpus callosum is best evaluated on which MRI plane for assessing callosal agenesis?

Sagittal (Correct answer)
Oblique
Coronal
Axial

Correct answer: Sagittal

The sagittal midline plane provides the best single view of the entire corpus callosum from genu to splenium for assessing agenesis or dysgenesis.

Question 161: The magnetic field's intensity is varied from head to foot by this gradient coil.

Z (Correct answer)
X
Y

Correct answer: Z

In most MRI systems, the main magnetic field (B0) is oriented along the Z-axis, which typically runs from the patient's head to foot. The Z-gradient coil is specifically designed to create a linear variation in the magnetic field strength along this Z-axis. This allows for precise slice selection and spatial encoding in the head-to-foot dimension.

Question 162: The quantity of determines the receiver bandwidth.

Phase changes within the matrix
Frequency samples in the matrix (Correct answer)

Correct answer: Frequency samples in the matrix

The receiver bandwidth in MRI is directly determined by the number of frequency samples (pixels) in the frequency encoding direction. A higher number of samples requires a wider bandwidth to accurately capture the range of frequencies present in the signal within the acquisition time. This ensures proper spatial resolution and minimizes aliasing artifacts in the resulting image.

Question 163: Which of the following best explains why a phased-array coil improves SNR compared to a body coil?

Multiple smaller coil elements are positioned close to the anatomy, maximizing signal pickup while limiting noise volume (Correct answer)
Phased-array coils use higher magnetic field strength
They increase the repetition time automatically
They apply stronger RF pulses to excite more protons

Correct answer: Multiple smaller coil elements are positioned close to the anatomy, maximizing signal pickup while limiting noise volume

Each element of a phased-array coil is small and close to the anatomy, providing high sensitivity to local signal with limited noise, and their combined data significantly improves overall SNR.

Question 164: In contrast to SE, GRE sequences employ

greater TE and TR lengths
longer TE and shorter TR
shorter TE and longer TR
reduced TR and TE lengths (Correct answer)

Correct answer: reduced TR and TE lengths

Gradient Echo (GRE) sequences typically employ significantly shorter repetition times (TR) and echo times (TE) compared to Spin Echo (SE) sequences. This is feasible because GRE sequences use smaller flip angles for excitation and do not require the longer timing associated with the 180-degree refocusing pulses. These reduced TR and TE values enable much faster image acquisition, which is advantageous for dynamic imaging or when scan speed is crucial.

Question 165: The range of frequencies sampled during the process is represented by the receiver bandwidth.

phase difference
gradient coils
gradient of frequency encoding (Correct answer)
gradient for slice selection

Correct answer: gradient of frequency encoding

The receiver bandwidth in MRI represents the range of frequencies sampled during the signal acquisition process. This range of frequencies is directly linked to the frequency encoding gradient, which spatially encodes information along one dimension of the image. A wider bandwidth allows for faster acquisition but can lead to a reduction in signal-to-noise ratio (SNR).

Question 166: In a spin-echo sequence, which combination of TR and TE produces a T2-weighted image?

Short TR, long TE
Short TR, short TE
Long TR, long TE (Correct answer)
Long TR, short TE

Correct answer: Long TR, long TE

T2-weighting requires long TR (to minimize T1 contrast by allowing full recovery) and long TE (to allow T2 differences between tissues to accumulate).

Question 167: Diffusion tensor imaging (DTI) and tractography are primarily used to evaluate which brain structure?

Metabolite concentrations
White matter fiber tracts and connectivity (Correct answer)
Gray matter cortical thickness
Cerebral blood flow

Correct answer: White matter fiber tracts and connectivity

DTI measures the directional diffusion of water in white matter to map axonal fiber tracts, enabling tractography of major pathways such as the corticospinal tract.

Question 168: When performing MRI on a patient with an insulin pump, which step is essential before beginning the exam?

Leave the pump in place since insulin is not ferromagnetic
Tape the pump to the patient's leg during the scan
Increase the insulin dose before scanning
Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning (Correct answer)

Correct answer: Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning

Insulin pumps may malfunction, heat, or be damaged in the MRI environment; removal or manufacturer verification of MR-conditional status is mandatory.

Question 169: A technologist who holds an RT(MR)(ARRT) credential and allows it to lapse must complete which process to reinstate it?

Complete only a practical competency evaluation
Resubmit all original application materials and retake the exam
Apply for reinstatement and fulfill CE requirements (Correct answer)
Retake the full MRI registry examination

Correct answer: Apply for reinstatement and fulfill CE requirements

ARRT allows lapsed credential holders to reinstate by applying for reinstatement and meeting outstanding CE obligations.

Question 170: What is the recommended action when a patient with an unknown metallic implant cannot be identified before a clinically urgent MRI?

Cancel the exam without exception
Proceed with the scan at lowest SAR
Consult the radiologist and ordering physician to assess risk vs. benefit (Correct answer)
Perform the scan with a 0.5T open system only

Correct answer: Consult the radiologist and ordering physician to assess risk vs. benefit

The radiologist and referring physician must jointly assess whether clinical urgency outweighs the unquantified risk of scanning with an unknown implant.

Question 171: Which positioning aid is used to maintain the ankle in a 90° neutral position during MRI to optimally visualize the Achilles tendon?

Vacuum immobilization device
Sand bag
Compression bandage
Ankle positioning block or foam wedge (Correct answer)

Correct answer: Ankle positioning block or foam wedge

A foam wedge or ankle block holds the foot perpendicular to the leg, minimizing magic angle artifact and providing consistent Achilles tendon orientation.

Question 172: Which ligament of the knee is best seen on sagittal MRI images and connects the posterior femur to the anterior tibia?

Posterior cruciate ligament
Anterior cruciate ligament (Correct answer)
Arcuate ligament
Medial collateral ligament

Correct answer: Anterior cruciate ligament

The anterior cruciate ligament (ACL) runs from the posterior lateral femoral condyle to the anterior tibial spine and is best evaluated on sagittal MRI.

Question 173: The central lines of k-space mainly determine which property of the final MR image?

Slice thickness
Field of view in the frequency direction
Image signal and contrast (Correct answer)
Fine detail and edge sharpness

Correct answer: Image signal and contrast

The low spatial-frequency data near the center of k-space is acquired with the weakest phase-encoding gradients, so it carries the most signal. It sets the overall signal-to-noise and contrast of the image. The outer (high spatial-frequency) lines carry fine detail and spatial resolution.

Question 174: Rapidly switching gradient fields (dB/dt) most directly cause which effect?

Tissue heating from RF
Projectile accidents
Ionization of tissue
Peripheral nerve stimulation (Correct answer)

Correct answer: Peripheral nerve stimulation

Fast-changing gradient fields induce currents in tissue that can stimulate peripheral nerves and cause tingling or twitching.

Question 175: What is the primary advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space (Correct answer)
They improve T1 contrast
They eliminate the need for gradient coils
They increase SNR at the same scan time

Correct answer: They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space

Parallel imaging exploits spatial sensitivity differences among phased-array coil elements to reconstruct fully sampled images from under-sampled k-space, reducing scan time by the acceleration factor (R).

Question 176: Parallel imaging techniques such as SENSE or GRAPPA shorten scan time mainly by:

Reducing the number of frequency-encoding samples
Raising the main magnetic field strength
Skipping some phase-encoding lines and using multi-element coil sensitivity data to fill them in (Correct answer)
Increasing the TR

Correct answer: Skipping some phase-encoding lines and using multi-element coil sensitivity data to fill them in

Parallel imaging undersamples k-space in the phase-encoding direction by an acceleration factor (R). It then uses the spatial sensitivity profiles of a multi-channel phased-array coil to unfold the aliased image (SENSE) or rebuild the missing lines (GRAPPA). The trade-off is lower SNR, roughly by the square root of R multiplied by the coil geometry (g) factor.

Question 177: When a constant magnetic field is present, hydrogen protons

Stay basically orientated randomly while rotating around the field axis. (Correct answer)
Align yourself along the field and revolve around its center.
do not experience any magnetic field effects
Ascend the field and rotate around its center.

Correct answer: Stay basically orientated randomly while rotating around the field axis.

When hydrogen protons are placed in a strong constant magnetic field (B0), they align either parallel or anti-parallel to the field, creating a slight net magnetization. However, individual protons do not simply align; they also precess (rotate) around the axis of the main magnetic field at their characteristic Larmor frequency. While there's a net alignment, their individual spin orientations remain somewhat random relative to each other as they precess.

Question 178: On an axial MRI of the abdomen at the level of L1, which structure is seen as a round low-signal structure anterior to the aorta?

Portal vein
Superior mesenteric artery (Correct answer)
Celiac axis
Inferior vena cava

Correct answer: Superior mesenteric artery

The superior mesenteric artery (SMA) arises from the anterior aorta at approximately L1 and appears as a round flow-void structure surrounded by fat on axial images.

Question 179: Inversion recovery sequences null a specific tissue when the readout pulse is applied at time TI equal to:

0.693 × T1 of the tissue (T1 × ln2) (Correct answer)
2 × T1 of the tissue
T1/2 of the tissue
0.5 × TE

Correct answer: 0.693 × T1 of the tissue (T1 × ln2)

The longitudinal magnetization of a tissue crosses zero at TI = T1 × ln(2) ≈ 0.693 × T1; applying the readout at this moment nulls that tissue's signal.

Question 180: On MRI of the prostate using PI-RADS scoring, which sequence is the most dominant sequence for peripheral zone lesions?

Diffusion-weighted imaging (DWI) (Correct answer)
Dynamic contrast-enhanced (DCE)
MR spectroscopy
T1-weighted

Correct answer: Diffusion-weighted imaging (DWI)

DWI is the dominant sequence for peripheral zone lesion characterization in the PI-RADS v2.1 scoring system for prostate MRI.

Question 181: What sound pressure level (dB) can MRI gradient noise reach, necessitating hearing protection for patients?

130–140 dB
99–115 dB (Correct answer)
75–85 dB
60–70 dB

Correct answer: 99–115 dB

MRI gradient switching can generate noise levels of 99–115 dB SPL, exceeding safe hearing thresholds and requiring earplugs or headphones for patients.

Question 182: Under IEC normal operating mode, what is the whole-body averaged SAR limit?

2 W/kg (Correct answer)
8 W/kg
4 W/kg
1 W/kg

Correct answer: 2 W/kg

Normal operating mode limits whole-body SAR to 2 W/kg, while first level controlled mode allows up to 4 W/kg.

Question 183: The 'late gadolinium enhancement' (LGE) pattern of subendocardial distribution in cardiac MRI is most consistent with which diagnosis?

Hypertrophic cardiomyopathy
Ischemic scar (prior myocardial infarction) (Correct answer)
Cardiac sarcoidosis
Myocarditis

Correct answer: Ischemic scar (prior myocardial infarction)

Subendocardial LGE following a coronary territory distribution is the classic pattern of ischemic scar from prior myocardial infarction.

Question 184: Which of the following maneuvers most directly reduces chemical shift artifact of the first kind?

Increase receiver bandwidth (Correct answer)
Apply fat suppression
Switch from spin echo to gradient echo
Increase field of view

Correct answer: Increase receiver bandwidth

Increasing the receiver bandwidth reduces the chemical shift displacement (measured in pixels) between fat and water signals along the frequency-encode direction.

Question 185: Positive susceptibility is present in these materials, however when exposed to an external magnetic field, they will stay magnetized even after the field is removed.

Superpapmagnetic
Diamagnetic
Ferromagnetic (Correct answer)
Paramagnetic

Correct answer: Ferromagnetic

Ferromagnetic materials are characterized by strong positive susceptibility and the ability to retain their magnetization even after the external magnetic field is removed. This property makes them suitable for creating permanent magnets. Examples include iron, nickel, and cobalt, which are strongly attracted to magnets and can become permanently magnetized.

Question 186: MR Conditional implants are safe to scan only when:

The patient gives verbal consent
The radiologist approves verbally
The scan time is under 30 minutes
Specific conditions of field strength, SAR, and gradient limits are met (Correct answer)

Correct answer: Specific conditions of field strength, SAR, and gradient limits are met

MR Conditional devices are safe only when the defined conditions of use (field strength, SAR, gradient dB/dt, scan duration) are strictly followed.

Question 187: What minimum distance from the MRI magnet bore is generally recommended to keep unsecured ferromagnetic oxygen cylinders?

Distance depends on field strength and cylinder size (Correct answer)
5 meters
1 meter
3 meters

Correct answer: Distance depends on field strength and cylinder size

The safe exclusion zone for ferromagnetic oxygen cylinders depends on both the scanner's field strength and the cylinder size, so no single fixed distance applies universally.

Question 188: Which sequence is fastest, acquiring all of k-space after one excitation, but is most prone to susceptibility distortion and N/2 ghosting?

Inversion recovery fast spin echo
Single-shot echo planar imaging (EPI) (Correct answer)
3D spoiled gradient echo
Conventional spin echo

Correct answer: Single-shot echo planar imaging (EPI)

Single-shot EPI fills k-space with a rapidly oscillating readout gradient, which makes it fast but sensitive to field inhomogeneity and phase errors.

Question 189: SSFP (steady-state free precession) sequences such as TrueFISP/FIESTA produce contrast that is proportional to which tissue property ratio?

T1/T2
TE/T2*
T2/T1 (Correct answer)
TR/T1

Correct answer: T2/T1

SSFP signal is proportional to T2/T1 ratio; tissues with high T2/T1 (like blood and fluids) appear very bright, making SSFP ideal for cardiac cine and vascular imaging.

Question 190: The difference between the hydrogen's periodic frequency in fat and water is known as

FID
FOURIER TRANSFORM
SPIN DENSITY
CHEMICAL SHIFT (Correct answer)

Correct answer: CHEMICAL SHIFT

Chemical shift refers to the slight difference in the resonant frequency of protons when they are in different chemical environments, such as those found in fat versus water molecules. This frequency difference arises because electron shielding around protons varies with their molecular bonds, causing them to experience slightly different effective magnetic fields. This phenomenon is exploited in MRI to differentiate tissues but can also lead to artifacts if not properly accounted for.

Question 191: In a spin echo (SE) sequence, increasing the repetition time (TR) while keeping TE short primarily results in:

Decreased T1 weighting (more proton density/T2-like contrast) (Correct answer)
Increased T2 weighting
Increased T1 weighting
Increased SNR only with no contrast change

Correct answer: Decreased T1 weighting (more proton density/T2-like contrast)

A long TR allows full T1 recovery of all tissues, reducing T1 contrast differences; combined with short TE, this produces proton density weighting.

Question 192: Wraparound (aliasing) artifact in MRI is caused by:

Structures outside the FOV contributing signal that is folded back into the image (Correct answer)
Phase errors from pulsatile flow
Gradient non-linearity at the edges of the bore
T2* dephasing from metallic objects

Correct answer: Structures outside the FOV contributing signal that is folded back into the image

When anatomy extends beyond the selected FOV in the phase-encode direction, it is aliased and appears superimposed on the opposite side of the image.

Question 193: In MRI, what does the term 'k-space' represent?

A map of gradient field inhomogeneities
The raw frequency-domain data before Fourier transformation into an image (Correct answer)
The final reconstructed image space
The physical space inside the MRI bore

Correct answer: The raw frequency-domain data before Fourier transformation into an image

K-space is the mathematical frequency domain where raw MRI data is stored; a Fourier transform converts k-space data into the final spatial image.

Question 194: Fast spin echo sequences, in contrast to spin echo, have

elevated susceptibility and elevated T2 weighting
T2 weighting increased but susceptibility decreased (Correct answer)
T2 weighting decreased but susceptibility rose
Diminished susceptibility and T2 weighting

Correct answer: T2 weighting increased but susceptibility decreased

Fast Spin Echo (FSE) sequences utilize multiple 180-degree refocusing pulses, which effectively reduce the impact of magnetic susceptibility artifacts by repeatedly rephasing spins. This leads to decreased susceptibility artifacts compared to conventional spin echo. Additionally, FSE sequences can achieve stronger T2 weighting due to the extended echo train and multiple echoes contributing to the signal, often resulting in increased T2 weighting.

Question 195: This kind of magnetic shielding confines the fringe field by using metal—typically steel—in the scan room walls.

Active
Passive (Correct answer)

Correct answer: Passive

Passive magnetic shielding involves lining the walls, floor, and ceiling of the MRI scan room with ferromagnetic materials, typically steel. This material absorbs and redirects the stray magnetic fields, known as fringe fields, produced by the main magnet. This effectively contains the magnetic field within the room, preventing interference with external devices or personnel.

Question 196: During a magnet quench, what is the main danger to people in the scan room if the quench pipe fails?

Ionizing radiation exposure
Asphyxiation and cryogenic burns from helium gas (Correct answer)
Sudden increase in magnetic field strength
Electrical shock from the gradient coils

Correct answer: Asphyxiation and cryogenic burns from helium gas

Boiling helium can displace oxygen and cause frostbite, so the room should be evacuated at once.

Question 197: In the context of the ARRT MRI registry, 'structured education' refers to which requirement?

Online CE modules totaling 50 hours
Attending MRI vendor training only
Completion of an accredited primary radiologic technology program (Correct answer)
Hospital orientation programs

Correct answer: Completion of an accredited primary radiologic technology program

Structured education means graduating from a formal, ARRT-recognized educational program as the foundation for registry eligibility.

Question 198: Which of the following changes will increase spatial resolution without changing the FOV?

Increasing slice thickness
Increasing NEX
Decreasing the matrix size
Increasing the matrix size (Correct answer)

Correct answer: Increasing the matrix size

Increasing matrix size means more phase and frequency encoding steps, reducing voxel size and improving spatial resolution within the same FOV.

Question 199: The normal intervertebral disc nucleus pulposus appears as which signal on T2-weighted MRI in a healthy young adult?

Intermediate signal
High signal (bright) (Correct answer)
Signal void
Low signal

Correct answer: High signal (bright)

The healthy nucleus pulposus is rich in water-containing proteoglycans and appears bright (high signal) on T2-weighted sequences.

Question 200: Which patient has the highest risk of nephrogenic systemic fibrosis after receiving gadolinium?

eGFR below 30 mL/min/1.73 m² or on dialysis (Correct answer)
eGFR of 95 mL/min/1.73 m²
eGFR of 65 mL/min/1.73 m²
A patient with a mild contrast allergy history

Correct answer: eGFR below 30 mL/min/1.73 m² or on dialysis

NSF risk is mainly in severe chronic kidney disease or acute kidney injury, especially with higher-risk (group I) agents.

Question 201: What is the primary consequence of using a high acceleration factor in parallel imaging?

Reduced scan time with no image quality loss
Improved T1 contrast
Increased spatial resolution
Reduced SNR due to the g-factor penalty (Correct answer)

Correct answer: Reduced SNR due to the g-factor penalty

High acceleration factors in parallel imaging introduce a geometry (g-factor) penalty that reduces SNR, especially in the center of the image where coil sensitivity overlap is less distinct.

Question 202: In a patient with an acute ischemic stroke, the infarcted region typically appears:

Bright on both DWI and the ADC map
Dark on DWI and bright on the ADC map
Bright on DWI and dark on the ADC map (Correct answer)
Dark on both DWI and the ADC map

Correct answer: Bright on DWI and dark on the ADC map

Cytotoxic edema restricts water diffusion, causing high DWI signal and a low apparent diffusion coefficient.

Question 203: Which organization accredits MRI education programs whose graduates may be eligible to sit for the ARRT MRI registry?

Joint Review Committee on Education in Radiologic Technology (JRCERT) (Correct answer)
The Joint Commission (TJC)
American Society of Radiologic Technologists (ASRT)
American College of Radiology (ACR)

Correct answer: Joint Review Committee on Education in Radiologic Technology (JRCERT)

JRCERT accredits radiologic technology education programs, and graduation from an accredited program satisfies ARRT educational requirements.

Question 204: When is a candidate's ARRT MRI registry exam score report typically available?

Immediately on screen at the testing center
Six weeks after the exam window closes
After 30 days by postal mail only
Within 3–5 business days via the ARRT website (Correct answer)

Correct answer: Within 3–5 business days via the ARRT website

ARRT posts official score reports to the candidate's online account within approximately 3–5 business days after testing.

Question 205: These materials are employed as T2 contrast agents because they show positive susceptibility, are stronger than paramagnetic materials but weaker than ferromagnetic materials.

Superpapmagnetic (Correct answer)
Ferromagnetic
Paramagnetic
Diamagnetic

Correct answer: Superpapmagnetic

Superparamagnetic materials possess magnetic properties stronger than paramagnetic substances but, unlike ferromagnetic materials, they do not retain magnetism once the external field is removed. They are often used as T2 contrast agents in MRI because their large magnetic moments create significant local field inhomogeneities, leading to rapid T2 decay and signal loss, which enhances contrast in certain tissues.

Question 206: A technologist wants to reduce chemical shift artifact at the fat-water interface. Which parameter change is most appropriate?

Decrease the receiver bandwidth
Increase the FOV
Increase the receiver bandwidth (Correct answer)
Decrease the number of slices

Correct answer: Increase the receiver bandwidth

Increasing receiver bandwidth reduces the frequency difference between fat and water in pixel units, shrinking the spatial shift of fat signal relative to water signal.

Question 207: Susceptibility-weighted imaging (SWI) is particularly sensitive to which types of tissue or substances?

Myelinated white matter
Fat and water interfaces
Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures (Correct answer)
Gadolinium-enhanced tissue

Correct answer: Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures

SWI exploits magnetic susceptibility differences between tissues; hemosiderin, deoxyhemoglobin, calcium, and iron create local field distortions that appear as marked hypointensity on SWI images.

Question 208: A 'corduroy' or 'herringbone' artifact covering the entire image is most often caused by:

Gradient eddy currents
A spike (impulse noise) in k-space (Correct answer)
Patient motion
RF transmitter miscalibration

Correct answer: A spike (impulse noise) in k-space

A single corrupted point (spike) in k-space Fourier-transforms into a sinusoidal wave overlaid across the entire image, producing a corduroy or herringbone pattern.

Question 209: A patient reports a prior allergic-like reaction to a GBCA. Which of the following is the recommended premedication protocol?

Corticosteroid + antihistamine, with the first steroid dose 13 hours before injection (Correct answer)
No premedication is effective for GBCA reactions
Antihistamine only, 1 hour before
Aspirin 24 hours before

Correct answer: Corticosteroid + antihistamine, with the first steroid dose 13 hours before injection

The ACR-recommended premedication protocol for prior GBCA reactions includes corticosteroids given 13, 7, and 1 hour before contrast, combined with an antihistamine 1 hour before.

Question 210: Magnetization of hydrogen using MRI

perpendicular to the primary magnetic field (Correct answer)
In the primary magnetic field path

Correct answer: perpendicular to the primary magnetic field

In MRI, the detectable signal is generated from transverse magnetization, which is created when an RF pulse tips the net magnetization of hydrogen protons away from the primary magnetic field (B0). This transverse magnetization precesses perpendicular to B0, inducing a current in the receiver coil. Therefore, the magnetization used for signal detection is perpendicular to the primary magnetic field.

Question 211: Multiple sclerosis (MS) plaques in the brain are classically found in which location on MRI?

Cerebellum exclusively
Basal ganglia bilaterally
Gray matter of the cortex only
Periventricular white matter, corpus callosum, and juxtacortical regions (Correct answer)

Correct answer: Periventricular white matter, corpus callosum, and juxtacortical regions

MS demyelinating plaques characteristically occur in periventricular white matter, corpus callosum (Dawson fingers), juxtacortical, and infratentorial regions.

Question 212: Which patient positioning accessory is routinely used to reduce hand and wrist movement during an MRI wrist examination?

Knee support wedge under the wrist
Dedicated wrist coil with the patient prone and arm extended overhead ('Superman position') (Correct answer)
Foam head cushion
Compression wrap around the shoulder

Correct answer: Dedicated wrist coil with the patient prone and arm extended overhead ('Superman position')

The 'Superman position' with the arm extended overhead minimizes the distance from wrist to isocenter and uses a dedicated wrist coil, optimizing SNR and reducing motion artifact.

Question 213: The placement of the slice is established by the

The RF pulse's transmit frequency (Correct answer)
phase difference
frequency of the RF pulse received
Radiofrequency coil's transmit frequency

Correct answer: The RF pulse's transmit frequency

The placement of the slice in MRI is precisely established by the transmit frequency of the RF pulse. When a magnetic field gradient is applied, protons at different locations precess at different frequencies. By selecting a specific RF transmit frequency, only protons resonating at that exact frequency within the gradient field will be excited, thereby defining the slice's position.

Question 214: Which of the following precautions is required before administering a GBCA to a breastfeeding mother, according to ACR recommendations?

The infant must receive a blood test before the mother can resume breastfeeding
Breastfeeding should be interrupted for 24–48 hours after GBCA administration
No precautions are required as only trace amounts enter breast milk (Correct answer)
Breastfeeding must be permanently stopped

Correct answer: No precautions are required as only trace amounts enter breast milk

The ACR states that GBCAs enter breast milk in very small amounts (<0.04%) and oral bioavailability is negligible; no interruption is required, though the mother may choose to withhold for 12–24 hours if concerned.

Question 215: Substances in the presence of an applied magnetic field that show a modest rise in magnetic field. They exhibit both positive and low susceptibility.

Superpapmagnetic
Diamagnetic
Ferromagnetic
Paramagnetic (Correct answer)

Correct answer: Paramagnetic

Paramagnetic materials exhibit a weak, positive susceptibility to an external magnetic field. Their unpaired electrons align with the field, causing a modest increase in the local magnetic field, but this effect is lost once the external field is removed. Gadolinium, a common MRI contrast agent, is a well-known paramagnetic substance.

Question 216: The echo time (TE) in gradient-echo sequences affects which type of contrast?

Proton density contrast only
T1 contrast only
T2* contrast — longer TE increases T2* weighting and susceptibility effects (Correct answer)
TR governs all contrast in GRE sequences

Correct answer: T2* contrast — longer TE increases T2* weighting and susceptibility effects

In gradient-echo sequences, TE controls T2* contrast; longer TE allows greater T2* dephasing, increasing susceptibility effects from blood products, iron, and air-tissue interfaces.

Question 217: For a spoiled gradient echo sequence, the flip angle that gives maximum signal for a tissue with a given T1 and TR is called the:

Nyquist angle
Magic angle
Ernst angle (Correct answer)
Larmor angle

Correct answer: Ernst angle

The Ernst angle, where cos θ = e^(-TR/T1), produces the highest signal for a given TR and T1.

Question 218: Which gradient-echo sequence uses a very short TR and a spoiler gradient to eliminate residual transverse magnetization before the next RF pulse?

Spoiled gradient echo (SPGR/FLASH) (Correct answer)
GRASS
Steady-state free precession (SSFP/TrueFISP)
FIESTA

Correct answer: Spoiled gradient echo (SPGR/FLASH)

Spoiled GRE sequences (SPGR, FLASH) use RF or gradient spoiling to destroy residual transverse magnetization between pulses, producing T1-weighted images with high SNR efficiency.

Question 219: Which type of question format is exclusively used on the ARRT MRI registry computer-based examination?

Matching
Multiple choice with one best answer (Correct answer)
Fill-in-the-blank
True/False

Correct answer: Multiple choice with one best answer

The ARRT MRI exam uses only multiple-choice questions with four options and one best answer.

Question 220: On MRI of the liver, a simple hepatic cyst is expected to show which signal characteristics?

T1 high, T2 high, with peripheral enhancement
T1 low, T2 low
T1 high, T2 low
T1 low, T2 high, no enhancement (Correct answer)

Correct answer: T1 low, T2 high, no enhancement

Simple hepatic cysts have low T1 signal, very high T2 signal due to pure fluid content, and show no contrast enhancement.

Question 221: In a gradient echo sequence, what replaces the 180° refocusing pulse used in spin echo?

A slice-select gradient reversal
A phase-encoding rewinder gradient
A reversed readout gradient (Correct answer)
A second 90° RF pulse

Correct answer: A reversed readout gradient

Gradient echo sequences use a reversed readout gradient to rephase spins, making them sensitive to T2* rather than T2.

Question 222: Which sequence parameter directly controls the slice thickness in a 2D spin-echo acquisition?

TR duration
TE duration
Bandwidth of the readout gradient
Bandwidth of the RF pulse divided by the slice-select gradient amplitude (Correct answer)

Correct answer: Bandwidth of the RF pulse divided by the slice-select gradient amplitude

Slice thickness = RF pulse bandwidth ÷ slice-select gradient amplitude; thicker slices can be produced by widening the RF bandwidth or reducing the gradient strength.

Question 223: On a phase contrast flow study, velocities above the selected VENC will cause:

Aliasing, where high velocities are shown as flow in the opposite direction (Correct answer)
Zipper artifact across the phase direction
Complete fat suppression failure
Signal void from intravoxel dephasing only

Correct answer: Aliasing, where high velocities are shown as flow in the opposite direction

Phase shifts beyond ±180° wrap around, so velocities exceeding the VENC are encoded as flow in the opposite direction.

Question 224: MR spectroscopy (MRS) of the brain measures metabolite concentrations. Which metabolite, reduced in neuronal loss and gliosis, is considered a marker of neuronal integrity?

Choline (Cho)
N-acetylaspartate (NAA) (Correct answer)
Lactate (Lac)
Creatine (Cr)

Correct answer: N-acetylaspartate (NAA)

NAA (N-acetylaspartate) is located predominantly in neurons; its reduction indicates neuronal loss or dysfunction, making it a key spectroscopic marker of neuronal integrity.

Question 225: Provide more coverage area without sacrificing signal-to-noise ratio by using numerous coils and receivers.

Quadrature
Phased array (Correct answer)
Vertical
Helmholtz pair

Correct answer: Phased array

Phased array coils consist of multiple small, independent receiver coils, each with its own receiver channel. This innovative design allows for a larger field of view (coverage area) without sacrificing the high signal-to-noise ratio (SNR) typically associated with smaller coils. The signals from individual coils are then combined to form a comprehensive and high-quality image.

Question 226: Traditional GRE order

Reduce the impact of residual transverse magnetization by using spoiler gradients. (Correct answer)
Maintain transverse magnetization for additional attempts
To lessen the impact of residual transverse magnetization, use long TR.

Correct answer: Reduce the impact of residual transverse magnetization by using spoiler gradients.

In traditional (spoiled) Gradient Echo (GRE) sequences, spoiler gradients are applied at the end of each TR period. The primary purpose of these gradients is to intentionally dephase any residual transverse magnetization. This prevents the magnetization from contributing to the signal in subsequent TRs, ensuring that the signal primarily reflects T1 weighting and maintains consistent image contrast by avoiding contamination from previous excitations.

Question 227: What does the acronym STIR stand for, and what tissue does it primarily null?

Short-T1 Inversion Recovery — nulls fat signal (Correct answer)
Standard Tissue Inversion Recovery — nulls all tissue equally
Steady-state T1 Inversion Recovery — nulls water signal
Short-TE Inversion Recovery — nulls fat signal

Correct answer: Short-T1 Inversion Recovery — nulls fat signal

STIR (Short-T1 Inversion Recovery) applies an inversion pulse with a TI timed to null fat signal (TI ≈ 150 ms at 1.5T), providing robust fat suppression independent of B0 homogeneity.

Question 228: For imaging the brachial plexus, which specialized MRI sequence is most useful for nerve visualization?

Diffusion-weighted imaging
STIR or fat-suppressed T2 coronal (Correct answer)
T1 axial post-contrast
GRE in-phase

Correct answer: STIR or fat-suppressed T2 coronal

Fat-suppressed T2 or STIR coronal images suppress the surrounding fat signal and highlight the high-water-content neural tissue of the brachial plexus.

Question 229: Which MRI protocol modification is used to evaluate the acetabular labrum of the hip with maximum sensitivity for tears?

Standard T2 FSE without contrast
T1 fat-saturated without contrast
MR arthrography with intra-articular gadolinium dilution (Correct answer)
Diffusion-weighted imaging of the hip

Correct answer: MR arthrography with intra-articular gadolinium dilution

MR arthrography with intra-articular dilute gadolinium distends the joint capsule, separating the labrum from the femoral head and maximizing sensitivity for labral tears.

Question 230: For MRI of the breast, the patient should be positioned in which orientation?

Upright sitting position
Lateral decubitus on the affected side
Prone with breasts hanging freely in a dedicated bilateral breast coil (Correct answer)
Supine with arms at sides

Correct answer: Prone with breasts hanging freely in a dedicated bilateral breast coil

Prone positioning with the breasts hanging freely in dedicated bilateral surface coils minimizes motion and maximizes coil coupling for optimal breast MRI.

ARRT MRI Exam

The ARRT Magnetic Resonance Imaging examination certifies technologists in MRI, assessing competency in patient care, MRI safety, image production physics and sequences, and clinical imaging procedures.

230

Questions

240 min

Time Limit

75%

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Sources & references

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