ARRT MRI Exam — Questions and Answers

Question 1: Which phase-encoding direction choice can help reduce motion artifact from breathing in abdominal MRI?

Orient phase encoding in the anterior-posterior direction to capture all motion
Increase the number of slices
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 2: Gradient echo (GRE) sequences differ from spin echo sequences primarily because GRE:

Cannot be used for dynamic contrast imaging
Always requires longer scan times
Uses a gradient reversal to form an echo, making it sensitive to magnetic susceptibility (T2*) (Correct answer)
Uses a 180° refocusing pulse to eliminate field inhomogeneity effects

Correct answer: Uses a gradient reversal to form an echo, making it sensitive to magnetic susceptibility (T2*)

GRE uses gradient reversal without a 180° refocusing pulse, making it sensitive to susceptibility effects (T2*) and allowing faster acquisition.

Question 3: Nephrogenic Systemic Fibrosis (NSF) is a serious complication associated with GBCA administration in patients with:

Severe renal impairment (GFR <30 mL/min/1.73m²) (Correct answer)
Active infection
Liver failure
Allergy to iodine

Correct answer: Severe renal impairment (GFR <30 mL/min/1.73m²)

NSF occurs almost exclusively in patients with severe kidney disease (GFR <30) because impaired renal clearance prolongs gadolinium exposure, allowing transmetallation and tissue deposition.

Question 4: Which MRI sequence is best suited for evaluating articular cartilage because it provides excellent contrast between cartilage, fluid, and bone?

Proton density fat-saturated (PD FS) (Correct answer)
FLAIR
T1-weighted SE
Inversion recovery (STIR)

Correct answer: Proton density fat-saturated (PD FS)

PD fat-saturated sequences highlight cartilage defects as intermediate-signal cartilage contrasts sharply against bright joint fluid and suppressed fat.

Question 5: Which breathing technique is recommended for upper abdominal MRI (liver, pancreas) to minimize respiratory motion artifact?

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

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

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

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

Susceptibility artifact
Gibbs ringing artifact
Aliasing (wrap-around) artifact (Correct answer)
Chemical shift 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 8: To form a magnet field, wires are arranged side by side.

Superconducting
Selenoid magnet (Correct answer)
Resistive magnet
Permanent magnet

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

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

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

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

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 11: A candidate who fails the ARRT MRI registry exam may retest after what mandatory waiting period?

30 days
90 days (Correct answer)
60 days
6 months

Correct answer: 90 days

ARRT requires a 90-day waiting period between examination attempts for registry candidates.

Question 12: How many CE credits are required per ARRT MRI biennium renewal cycle?

12
36
24 (Correct answer)
50

Correct answer: 24

ARRT mandates 24 continuing education credits every two years to renew the MRI registry credential.

Question 13: 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?

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

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 14: What is a 'quench' in MRI terminology?

A sudden loss of superconductivity causing helium boil-off (Correct answer)
A gradient coil failure
A rapid increase in field strength
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 15: Which MRI sequence is most sensitive to hemorrhage detection because of its sensitivity to blood products?

Fast spin echo (FSE)
Diffusion-weighted imaging (DWI)
Inversion recovery (IR)
Gradient echo (GRE) (Correct answer)

Correct answer: Gradient echo (GRE)

Gradient echo sequences are sensitive to magnetic susceptibility differences caused by hemosiderin and deoxyhemoglobin, making them ideal for detecting hemorrhage.

Question 16: What is the Larmor frequency in MRI?

The rate of T1 relaxation for water
The frequency at which gradient coils switch polarity
The resonant frequency at which protons precess in a given magnetic field (Correct answer)
The bandwidth of the RF receiver coil

Correct answer: The resonant frequency at which protons precess in a given magnetic field

The Larmor frequency (ω₀ = γB₀) is the precise resonant frequency at which protons absorb and emit RF energy in the applied field.

Question 17: The placement of the slice is established by the

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

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

Head MRI without contrast (Correct answer)
MRI-guided biopsy procedures
Cardiac MRI stress testing
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 19: FLAIR (Fluid-Attenuated Inversion Recovery) suppresses which signal and is most useful for detecting:

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

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 20: Under ARRT policy, which of the following must a registered MRI technologist report within 30 days?

Obtaining an additional college degree
Change of mailing address
A felony conviction or guilty plea (Correct answer)
Purchasing new MRI accessories

Correct answer: A felony conviction or guilty plea

ARRT's Standards of Ethics require technologists to report criminal convictions or guilty pleas within 30 days.

Question 21: On MRI, cortical bone appears as which signal intensity on both T1 and T2 weighted images?

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

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 22: The gradient subsystem's primary goal is to

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

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

TE/T2*
T1/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 24: 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
Quadrature
Vertical (Correct answer)
Phased array

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 25: In MRI, the term 'flip angle' refers to:

The angle by which the net magnetization is rotated from B0 by the RF pulse (Correct answer)
The angle of the gradient coils relative to the main magnet
The phase angle accumulated during readout
The angular difference between excitation and reception coils

Correct answer: The angle by which the net magnetization is rotated from B0 by the RF pulse

The flip angle is the degree of rotation of the net magnetization vector away from the longitudinal axis produced by an RF pulse.

Question 26: What is the preferred patient position and coil for imaging the rotator cuff of the shoulder?

Sitting upright, surface coil
Supine, arm at side in neutral rotation, dedicated shoulder coil (Correct answer)
Supine, arm abducted 90°, flex coil
Prone, body coil

Correct answer: Supine, arm at side in neutral rotation, dedicated shoulder coil

Supine positioning with the arm at the side in neutral rotation and a dedicated shoulder coil provides optimal SNR and comfort for rotator cuff imaging.

Question 27: What differentiates T2 from T2* is

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, or T2*, 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 28: Cardiac MRI uses which technique to synchronize data acquisition with the cardiac cycle and minimize cardiac motion artifact?

ECG gating or cardiac triggering (Correct answer)
Respiratory gating only
Real-time imaging without synchronization
Breath-hold sequences only

Correct answer: ECG gating or cardiac triggering

ECG gating (prospective triggering or retrospective gating) synchronizes k-space acquisition to specific phases of the cardiac cycle, minimizing motion artifact from myocardial contraction.

Question 29: EPI (echo planar imaging) sequences are particularly prone to which artifact caused by off-resonance spins accumulating phase during the long readout?

Magic angle artifact
Susceptibility artifact only in GRE
Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion (Correct answer)
Truncation 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 30: On brain MRI, the hippocampus is best evaluated for atrophy (as in Alzheimer's disease) on which plane?

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

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 31: In k-space, what does the center of k-space primarily determine?

Image contrast (Correct answer)
Echo time
Image resolution
Slice position

Correct answer: Image contrast

The center of k-space contains low spatial frequencies that carry the bulk of image contrast and overall signal intensity.

Question 32: Magnets formed of ferrous material found naturally or from blocks or slabs.

Selenoid
Reistive
Superconducting
Permanent (Correct answer)

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

SNR improves and scan time increases
Frequency-direction resolution decreases
Through-plane resolution is affected
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 34: A technologist who holds an RT(MR)(ARRT) credential and allows it to lapse must complete which process to reinstate it?

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

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

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

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 36: 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?

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

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 37: Which type of MRI coil surrounds the entire body and is used to transmit RF energy uniformly?

Phased-array coil
Gradient coil
Surface coil
Body (volume) coil (Correct answer)

Correct answer: Body (volume) coil

The body (volume) coil is built into the bore and provides uniform RF transmission across the entire patient.

Question 38: Which breast MRI positioning protocol is standard for screening and diagnostic evaluation?

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

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

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

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

Helmholtz pair
Quadrature
Vertical
Phased array (Correct answer)

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 41: What is the Specific Absorption Rate (SAR) a measure of in MRI?

Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass (Correct answer)
Contrast agent uptake rate in tissue
Rate of image data acquisition in k-space
Speed of gradient switching in Tesla per meter per second

Correct answer: Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass

SAR (W/kg) quantifies RF energy deposition in tissue and is a primary safety limit to prevent excessive tissue heating during MRI.

Question 42: 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 43: Which inversion recovery technique is used to suppress fat signal in musculoskeletal MRI?

STIR (Short TI Inversion Recovery) (Correct answer)
MPRAGE
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 44: What does the acronym STIR stand for, and what tissue does it primarily null?

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

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 45: The term 'T1 mapping' in cardiac MRI using gadolinium is used to quantify which clinically important tissue property?

Extracellular volume fraction (ECV) as a marker of fibrosis (Correct answer)
Myocardial perfusion rate
Coronary artery stenosis grade
Ejection fraction

Correct answer: Extracellular volume fraction (ECV) as a marker of fibrosis

Pre- and post-contrast T1 mapping allows calculation of the extracellular volume (ECV), which is an established quantitative biomarker of diffuse myocardial fibrosis.

Question 46: Which ARRT resource provides the official list of examination content categories, subcategories, and approximate percentage weighting for the MRI registry exam?

JRCERT program outcomes report
ASRT curriculum guide
ARRT Content Specifications document (Correct answer)
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 47: In a gradient echo sequence, what replaces the 180° refocusing pulse used in spin echo?

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

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 48: Which MRI artifact is caused by periodic patient motion such as cardiac or respiratory movement?

Chemical shift artifact
Magnetic susceptibility artifact
Gibbs ringing artifact
Ghosting (motion) artifact (Correct answer)

Correct answer: Ghosting (motion) artifact

Ghosting artifacts appear as repeated copies of moving structures along the phase-encoding direction due to periodic physiologic motion.

Question 49: What does a high b-value in diffusion-weighted imaging (DWI) indicate?

Lower magnetic field strength required
Faster acquisition with less motion sensitivity
Shorter echo time and less diffusion weighting
Stronger diffusion-sensitizing gradients and greater sensitivity to restricted diffusion (Correct answer)

Correct answer: Stronger diffusion-sensitizing gradients and greater sensitivity to restricted diffusion

The b-value reflects the strength and duration of diffusion-sensitizing gradients; higher b-values increase diffusion contrast but also reduce SNR.

Question 50: In MRI, what is k-space?

The region of the brain studied in neuroimaging
A unit of measurement for gradient strength
The physical space inside the magnet bore
The raw data space containing spatial frequency information used to reconstruct images (Correct answer)

Correct answer: The raw data space containing spatial frequency information used to reconstruct images

K-space is the mathematical domain that stores the raw MRI signal as spatial frequencies; a Fourier transform converts it into an image.

Question 51: 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 Conditional
MR Safe

Correct answer: MR Unsafe

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

Question 52: Which MRI sequence is the standard for evaluating the internal structure of bone marrow and is most sensitive to marrow infiltration or edema?

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

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 53: 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 54: 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.

Vertical
Helmholtz pair
Quadrature (Correct answer)
Phased array

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 55: Magnetization transfer contrast (MTC) in MRI works by:

Transferring longitudinal magnetization to neighboring voxels
Saturating bound protons in macromolecules, which reduces free water signal through exchange (Correct answer)
Using two different RF frequencies simultaneously to cancel fat signal
Applying a gradient to transfer magnetization between slices

Correct answer: Saturating bound protons in macromolecules, which reduces free water signal through exchange

Off-resonance RF pulses saturate the broad resonance of bound macromolecular protons; this saturation is transferred to free water protons via chemical exchange, reducing their signal.

Question 56: Which MRI sequence is most sensitive for detecting early bone marrow edema in stress fractures?

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

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

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

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

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

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

They improve T1 contrast
They eliminate the need for gradient coils
They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space (Correct answer)
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 60: 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)
T1 contrast increases
SNR improves due to longer signal collection

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

The raw frequency-domain data before Fourier transformation into an image (Correct answer)
A map of gradient field inhomogeneities
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 62: What causes the 'zipper' artifact that appears as a line of noise across the MRI image?

Eddy currents induced by gradient switching
Incomplete fat suppression
Patient motion during phase encoding
External RF interference entering the scan room through a breach in shielding (Correct answer)

Correct answer: External RF interference entering the scan room through a breach in shielding

A zipper artifact is caused by external RF noise at a specific frequency leaking into the Faraday-shielded room, appearing as a bright line at that frequency position.

Question 63: 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 holds a second radiography credential
Candidate has exceeded the CE deadline by one week
Candidate has a prior misdemeanor conviction on record (Correct answer)

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

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

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

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

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

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

Correct answer: Peripheral nerve stimulation

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

Question 67: Which parameter directly controls the degree of T2 weighting in a spin echo sequence?

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

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

Eliminating the need for radiofrequency pulses
Increasing the magnetic field strength
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 69: 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 70: Phase contrast MRI (PC-MRI) is primarily used to measure:

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

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

They block radiofrequency pulses to create contrast
They directly emit radio waves that increase signal
They increase T2 relaxation time, increasing signal on T2-weighted images
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 72: What is the primary advantage of using a higher-relaxivity GBCA (e.g., gadobenate dimeglumine) compared to a standard-relaxivity agent?

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

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

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

Correct answer: Larger voxels produce higher SNR

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

Question 74: For MRI of the knee, the standard patient position is:

Knee flexed 45°, patient supine without coil
Knee extended in slight external rotation (5–15°), patient supine in dedicated knee coil (Correct answer)
Knee hyperflexed, patient lateral
Knee flexed 90°, patient prone

Correct answer: Knee extended in slight external rotation (5–15°), patient supine in dedicated knee coil

The knee is imaged supine with slight external rotation (5–15°) to align the ACL parallel to the sagittal plane for optimal visualization within a dedicated knee coil.

Question 75: Iron oxide nanoparticles (e.g., USPIO) used as MRI contrast agents primarily shorten which relaxation time?

Neither T1 nor T2
T2 and T2* (susceptibility effect) (Correct answer)
T2 only with no T2* effect
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 76: Which gradient is primarily responsible for frequency encoding in MRI?

Phase-encoding gradient
Spoiler gradient
Readout gradient (Correct answer)
Slice-select gradient

Correct answer: Readout gradient

The readout (frequency-encoding) gradient is applied during signal acquisition, causing spins at different positions to precess at different frequencies.

Question 77: 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.

Rise time
Slew rate (Correct answer)
Coil configuration

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

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

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

It crosses the blood-brain barrier
It distributes only in hepatic tissue
It remains exclusively in the arterial system
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 80: Which of the following best describes the 'magic angle' artifact and at what angle it occurs?

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

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

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

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 82: Susceptibility-weighted imaging (SWI) exploits differences in which magnetic property between tissues?

Chemical shift
T1 relaxation time
Magnetic susceptibility (Correct answer)
Proton density

Correct answer: Magnetic susceptibility

SWI uses the phase and magnitude information from a long-TE GRE sequence to detect subtle differences in magnetic susceptibility (e.g., deoxyhemoglobin, iron, calcium).

Question 83: Which coil type provides the best signal-to-noise ratio (SNR) for a specific small anatomy because it is placed closest to the structure?

Volume coil
Head coil
Body coil
Surface coil (Correct answer)

Correct answer: Surface coil

Surface coils are placed directly over the anatomy of interest; their proximity maximizes SNR for superficial or small structures compared to larger volume coils.

Question 84: Which coil configuration is used to image the entire spine in a single acquisition with uniform SNR?

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

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

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

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

The ratio of TE to TR
The difference in signal between two adjacent tissues
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

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

Voxel volume × √(NEX) × √(scan time factors) (Correct answer)
1 / (TR × TE)
Flip angle / repetition time
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 88: 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.
Ascend the field and rotate around its center.
do not experience any magnetic field effects

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

Selenoid magnet (Correct answer)
Resistive magnet
Permanent magnet
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 90: In the context of the ARRT MRI registry, 'structured education' refers to which requirement?

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

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

Proceed with the scan at lowest SAR
Consult the radiologist and ordering physician to assess risk vs. benefit (Correct answer)
Cancel the exam without exception
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 92: The magnetic field's intensity is varied from head to foot by this gradient coil.

Y
X
Z (Correct answer)

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

Sagittal (Correct answer)
Axial
Oblique
Coronal

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 94: The ARRT MRI registry exam content specification places approximately what percentage of questions in the 'Procedures' domain?

10%
20%
35% (Correct answer)
50%

Correct answer: 35%

Approximately 35% of the MRI registry exam covers Procedures, making it one of the largest content areas.

Question 95: What is contrast-to-noise ratio (CNR) in MRI and why is it important?

The number of phase encodes used to improve tissue differentiation
The ratio of TR to TE for optimal contrast
The ratio of gadolinium dose to body weight
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 96: The echo time (TE) in gradient-echo sequences affects which type of contrast?

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

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

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

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 98: What is the purpose of crusher (spoiler) gradients in a spin echo sequence?

To dephase residual transverse magnetization before the next RF pulse (Correct answer)
To refocus magnetization after the 180° pulse
To select the imaging slice thickness
To encode spatial position in the frequency direction

Correct answer: To dephase residual transverse magnetization before the next RF pulse

Crusher gradients surround the 180° refocusing pulse to eliminate stimulated echoes from imperfect flip angles that could contaminate image quality.

Question 99: In the ACR zone system, who is responsible for controlling access to Zone III?

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

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

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
Administer epinephrine immediately

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

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

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 102: 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?

3 W/kg
4 W/kg (Correct answer)
1.5 W/kg
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 103: Which of the following is a documented risk of MRI during the first trimester of pregnancy?

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

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

X (Correct answer)
Y
Z

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

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

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 106: Which phenomenon causes the chemical shift artifact in MRI, and in which direction does it occur?

Resonance frequency difference between fat and water; frequency-encode direction (Correct answer)
T1 differences between tissues; readout direction
Susceptibility differences between tissues; phase-encode direction
B1 field inhomogeneity; slice-select direction

Correct answer: Resonance frequency difference between fat and water; frequency-encode direction

Fat protons resonate at ~3.5 ppm lower frequency than water, causing spatial misregistration along the frequency-encoding direction.

Question 107: What is the relationship between magnetic field strength (B0) and the Larmor frequency?

Larmor frequency is inversely proportional to B0
Larmor frequency is independent of B0
Larmor frequency is proportional to B0²
Larmor frequency is directly proportional to B0 (ω₀ = γ·B0) (Correct answer)

Correct answer: Larmor frequency is directly proportional to B0 (ω₀ = γ·B0)

The Larmor equation states ω₀ = γ·B0, so doubling the field strength doubles the resonance frequency (e.g., 63 MHz at 1.5T, 128 MHz at 3T for hydrogen).

Question 108: In MRI of the breast, a finding described as a 'rim-enhancing mass' on dynamic contrast imaging is most suspicious for:

Fat necrosis
Simple cyst
Malignant lesion (Correct answer)
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 109: Which of the following parameters most directly controls T1 contrast in a spin echo sequence?

Repetition time (TR) (Correct answer)
Flip angle in gradient echo
Bandwidth
Echo time (TE)

Correct answer: Repetition time (TR)

TR determines how much longitudinal relaxation occurs between excitations; a short TR emphasizes T1 differences because tissues with shorter T1 recover faster.

Question 110: What is the primary reason gadolinium-based contrast agents should not be used in patients undergoing hemodialysis without a specific clinical indication?

Risk of anaphylaxis is higher in dialysis patients
Risk of NSF remains even after hemodialysis removes gadolinium (Correct answer)
Dialysis filters destroy the contrast agent before it reaches the target tissue
Gadolinium is not effectively removed by standard hemodialysis

Correct answer: Risk of NSF remains even after hemodialysis removes gadolinium

While hemodialysis can remove most gadolinium, some residual free gadolinium remains after each session, and repeated exposure can still cause NSF in high-risk patients.

Question 111: The apparent diffusion coefficient (ADC) map is calculated to eliminate which confounding effect in DWI?

T1 recovery
T2 shine-through (Correct answer)
Chemical shift misregistration
Gibbs ringing

Correct answer: T2 shine-through

ADC maps remove T2 shine-through by computing the diffusion coefficient from multiple b-values, isolating true diffusion restriction from long-T2 tissue signal.

Question 112: These materials are employed as T2 contrast agents because they show positive susceptibility, are stronger than paramagnetic materials but weaker than ferromagnetic materials.

Paramagnetic
Ferromagnetic
Diamagnetic
Superpapmagnetic (Correct answer)

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

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

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

Gradient-induced peripheral nerve stimulation
RF-induced heating from looped or coiled cables (Correct answer)
Quench event beginning
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 115: For imaging the brachial plexus, which specialized MRI sequence is most useful for nerve visualization?

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

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

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

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 117: Which ARRT ethics requirement must be fulfilled as part of the MRI registry application process?

CPR certification
Magnetic field safety officer training
Advanced cardiac life support (ACLS)
Pre-application ethics review if applicable (Correct answer)

Correct answer: Pre-application ethics review if applicable

Applicants with certain violations must complete a pre-application review, and all applicants must attest to meeting ARRT's Standards of Ethics.

Question 118: How many scored questions appear on the ARRT MRI registry examination?

220
200
100
175 (Correct answer)

Correct answer: 175

The ARRT MRI exam contains 175 scored questions plus a small number of unscored pilot questions.

Question 119: Which type of aneurysm clip is considered MR Unsafe regardless of age or appearance?

Ferromagnetic stainless steel clips (Correct answer)
Cobalt-chromium clips
Titanium 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 120: What is the purpose of applying a saturation band in MRI?

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

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 121: Which MRI sequence is most sensitive for detecting acute subarachnoid hemorrhage?

Diffusion-Weighted Imaging (DWI)
FLAIR (Fluid Attenuated Inversion Recovery) (Correct answer)
Gradient Echo (GRE)
T2-weighted FSE

Correct answer: FLAIR (Fluid Attenuated Inversion Recovery)

FLAIR suppresses CSF signal, making subarachnoid blood appear hyperintense against a dark CSF background.

Question 122: For MRI of the breast, the patient should be positioned in which orientation?

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

Question 123: What minimum distance from the MRI magnet bore is generally recommended to keep unsecured ferromagnetic oxygen cylinders?

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

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

Zone IV (Correct answer)
Zone III
Zone II
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 125: Fast spin echo (FSE/TSE) sequences reduce scan time compared to conventional spin echo by:

Acquiring multiple phase-encoding lines after each 90° excitation (echo train) (Correct answer)
Increasing the voxel size to reduce k-space lines needed
Reducing the number of slices acquired
Using a shorter repetition time

Correct answer: Acquiring multiple phase-encoding lines after each 90° excitation (echo train)

FSE uses a train of 180° pulses after each excitation to fill multiple k-space lines per TR, reducing total scan time by a factor equal to the echo train length.

Question 126: Which ARRT exam content domain addresses gradient performance, field homogeneity, and RF coil function?

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

Correct answer: Physics and Instrumentation

Physics and Instrumentation covers hardware components including gradients, RF coils, and magnet systems.

Question 127: In a spin echo (SE) sequence, increasing the repetition time (TR) while keeping TE short primarily results in:

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

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 128: What does k-space represent in MRI?

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

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

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

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

CHEMICAL SHIFT (Correct answer)
FOURIER TRANSFORM
FID
SPIN DENSITY

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

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

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 132: Continuing education (CE) requirements for ARRT MRI credential renewal are completed over what cycle length?

3 years
5 years
2 years (Correct answer)
1 year

Correct answer: 2 years

ARRT requires 24 CE credits completed within a 2-year renewal cycle to maintain the MRI credential.

Question 133: What is the effect of increasing receiver bandwidth on MRI image quality?

SNR decreases but chemical shift artifact is reduced (Correct answer)
Spatial resolution decreases
Image contrast improves significantly
SNR increases and scan time 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 134: For a brain MRI, which standard plane best demonstrates the corpus callosum in its entirety?

Sagittal (Correct answer)
Oblique
Coronal
Axial

Correct answer: Sagittal

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

Question 135: Which of the following is the most effective method to reduce motion artifact from bowel peristalsis in abdominal MRI?

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

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

Selenoid magnet
Superconducting (Correct answer)
Permanent magnet
Resistive magnet

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 137: Which MRI-specific safety topic is explicitly listed under the ARRT exam content specifications within Patient Care and Education?

Radiofrequency power amplifier maintenance
Cryogen manufacturing standards
Screening for implants and metallic foreign bodies (Correct answer)
Gradient coil winding techniques

Correct answer: Screening for implants and metallic foreign bodies

Screening patients for implants and metallic foreign bodies is a core patient safety responsibility explicitly included in the content specifications.

Question 138: A 'corduroy' or 'herringbone' artifact covering the entire image is most often caused by:

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

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

Right lateral and left lateral
Supine and prone
Clenched and relaxed
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 140: Which coil type generally provides the highest SNR for imaging a small superficial structure?

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

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

A single 90° pulse followed by multiple 180° refocusing pulses (echo train) (Correct answer)
Rapidly toggling the frequency-encoding gradient
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 142: What is the function of the shim coils in an MRI system?

Produce the rapidly switching gradients for slice selection
Compensate for inhomogeneities in the B0 field to improve field uniformity (Correct answer)
Amplify the RF signal received from the patient
Generate the main static magnetic field

Correct answer: Compensate for inhomogeneities in the B0 field to improve field uniformity

Shim coils generate small corrective magnetic fields that counteract spatial variations in B0, improving homogeneity and image quality.

Question 143: What sound pressure level (dB) can MRI gradient noise reach, necessitating hearing protection for patients?

60–70 dB
130–140 dB
99–115 dB (Correct answer)
75–85 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 144: Which patient condition requires consultation with the ordering physician regarding MRI safety due to potential risks during the first trimester?

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

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

Dynamic susceptibility contrast (DSC) MRI
Arterial spin labeling (ASL) (Correct answer)
Phase contrast MRI
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 146: On a T1-weighted MRI, which substance normally appears hyperintense (bright)?

Cerebrospinal fluid
Edema
Cortical bone
Subacute blood (methemoglobin) (Correct answer)

Correct answer: Subacute blood (methemoglobin)

Methemoglobin in subacute hemorrhage shortens T1 relaxation time, producing a bright signal on T1-weighted images.

Question 147: Which sequence parameter directly controls the slice thickness in a 2D spin-echo acquisition?

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

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

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

Correct answer: Image Production

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

Question 149: Diffusion tensor imaging (DTI) and tractography are primarily used to evaluate which brain structure?

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

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 150: In a spin-echo sequence, what is the role of the 180° refocusing pulse?

It encodes spatial information along the frequency direction
It suppresses fat signal by inverting its magnetization
It reverses phase dispersion caused by static field inhomogeneities to form an echo (Correct answer)
It excites protons from equilibrium into the transverse plane

Correct answer: It reverses phase dispersion caused by static field inhomogeneities to form an echo

The 180° pulse flips the transverse magnetization so that faster and slower precessing spins rephase, forming a spin echo and eliminating fixed inhomogeneity effects.

Question 151: Which gradient is responsible for determining slice position in a 2D MRI acquisition?

Frequency-encoding gradient
Phase-encoding gradient
Spoiler gradient
Slice-selection gradient (Correct answer)

Correct answer: Slice-selection gradient

The slice-selection gradient is applied simultaneously with the RF pulse to excite only protons in the desired anatomical plane.

Question 152: On a coronal MRI of the knee, which structure appears as a low-signal C-shaped band along the tibial plateau?

Medial meniscus (Correct answer)
Anterior cruciate ligament
Iliotibial band
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 153: A pregnant MRI technologist should follow which guideline regarding working in the MRI suite?

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

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 154: 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
Frequency-encoding direction
Slice-selection 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 155: On MRI of the liver, a simple hepatic cyst is expected to show which signal characteristics?

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

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 156: Which of the following is NOT an acceptable primary pathway for ARRT MRI registry eligibility?

Hold a primary ARRT certification in radiography
Hold a primary ARRT certification in nuclear medicine technology
Hold an associate degree only with no primary ARRT credential (Correct answer)
Hold a primary ARRT certification in radiation therapy

Correct answer: Hold an associate degree only with no primary ARRT credential

Candidates must hold a current primary ARRT certification in an approved discipline; an associate degree alone does not satisfy eligibility.

Question 157: Multiple sclerosis (MS) plaques in the brain are classically found in which location on MRI?

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

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

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

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

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

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 160: What is the effect of increasing the number of signal averages (NSA/NEX) on MRI image quality?

Scan time decreases
SNR decreases proportionally
Spatial resolution increases
SNR improves proportionally to the square root of NSA (Correct answer)

Correct answer: SNR improves proportionally to the square root of NSA

Averaging multiple acquisitions improves SNR by a factor of √NSA, though it linearly increases scan time.

Question 161: What does 'isotropic voxel' mean in MRI acquisition?

Voxel with equal field strength in all dimensions
Voxel with equal dimensions in all three spatial directions (Correct answer)
Voxel that produces equal signal in T1 and T2 sequences
Voxel aligned with the main magnetic field

Correct answer: Voxel with equal dimensions in all three spatial directions

An isotropic voxel has identical length, width, and height, allowing high-quality multiplanar reformats without resolution loss.

Question 162: Which technique is most effective for reducing susceptibility artifact from a metallic implant in MRI?

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

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 163: The 'ABER' position used in shoulder MRI arthrography stands for:

Abduction and Elbow Rest
Abduction and Endorotation
Abduction and External Rotation (Correct answer)
Adduction and External Rotation

Correct answer: Abduction and External Rotation

ABER (Abduction and External Rotation) positions the arm to tension the inferior glenohumeral ligament and improve detection of partial-thickness undersurface rotator cuff tears.

Question 164: Which MRI technique is used to assess brain perfusion by tracking the first pass of a gadolinium bolus?

Magnetic Resonance Spectroscopy (MRS)
Diffusion Tensor Imaging (DTI)
Dynamic Susceptibility Contrast (DSC) perfusion (Correct answer)
Arterial Spin Labeling (ASL)

Correct answer: Dynamic Susceptibility Contrast (DSC) perfusion

DSC perfusion MRI uses rapid T2*-weighted sequences to measure signal drop as gadolinium transits through the brain capillaries.

Question 165: Which MRI pulse sequence is most commonly used to perform MR angiography without contrast injection?

Inversion recovery with fat suppression
Echo planar imaging (EPI)
Spin echo with long TR/TE
Time-of-flight (TOF) angiography (Correct answer)

Correct answer: Time-of-flight (TOF) angiography

TOF MRA relies on flow-related enhancement: unsaturated blood flowing into a saturated imaging slice produces high signal relative to stationary tissue.

Question 166: What is the term for the MRI safety classification that indicates a device has been tested and found safe under specified conditions?

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

Correct answer: MR Conditional

MR Conditional means the device poses no known hazards when used within the specific conditions (field strength, SAR, gradient limits) stated by the manufacturer.

Question 167: 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)
Creatine (Cr)
N-acetylaspartate (NAA) (Correct answer)
Lactate (Lac)

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 168: Gibbs (truncation) artifact is caused by:

Aliasing from a FOV smaller than the patient
Patient motion during scanning
Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces (Correct answer)
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 169: In MR angiography, time-of-flight (TOF) technique produces vascular signal by exploiting which physical principle?

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

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

Conventional T1 spin echo and MRCP
DWI, fMRI, and perfusion imaging (Correct answer)
STIR and inversion recovery sequences
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 171: 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?

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

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

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

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

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

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

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 175: Which MRI artifact appears as a ghosting or smearing of bright structures in the phase-encoding direction?

Gibbs (truncation) artifact
Susceptibility artifact
Chemical shift artifact
Motion (ghosting) artifact (Correct answer)

Correct answer: Motion (ghosting) artifact

Motion artifact manifests as ghost images displaced in the phase-encoding direction because phase-encoding samples data over many TR intervals while frequency encoding is instantaneous.

Question 176: 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 177: One forms a spin echo through

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

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 178: Which MRI registry credential is awarded by the American Registry of Radiologic Technologists (ARRT) for MRI technologists?

MRI(ARRT)
MR(ARRT)
RMT(ARRT)
RT(MR)(ARRT) (Correct answer)

Correct answer: RT(MR)(ARRT)

The ARRT awards the RT(MR)(ARRT) credential to registered technologists who pass the MRI examination.

Question 179: Which portion of k-space primarily determines image contrast?

The edges equally with the center
The corners of k-space only
The periphery (high spatial frequencies)
The center (low spatial frequencies) (Correct answer)

Correct answer: The center (low spatial frequencies)

The center of k-space contains low spatial frequency data, which encodes the bulk signal intensity and contrast of the image.

Question 180: Which GBCA is approved by the FDA as a liver-specific agent taken up by hepatocytes?

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

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 181: What is the maximum number of times a candidate may attempt the ARRT MRI registry examination?

3 times total
Unlimited attempts
6 times total (Correct answer)
5 times within 5 years

Correct answer: 6 times total

ARRT limits candidates to 6 total examination attempts for any given credential.

Question 182: Which positioning aid is used to maintain the ankle in a 90° neutral position during MRI to optimally visualize the Achilles tendon?

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

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

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

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 184: 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 185: For a contrast-enhanced MRA of the aorta, the bolus tracking technique monitors contrast arrival in which vessel to trigger the 3D acquisition?

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

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

0.1 mmol/kg (Correct answer)
0.01 mmol/kg
0.3 mmol/kg
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 187: Which property of hydrogen makes it the most commonly used nucleus in clinical MRI?

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

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 188: In diffusion-weighted imaging (DWI), a high b-value results in:

Less diffusion weighting and higher signal
Increased signal from rapidly diffusing molecules
Greater diffusion weighting and lower overall signal (Correct answer)
Reduced T2 contribution to signal

Correct answer: Greater diffusion weighting and lower overall signal

Higher b-values apply stronger diffusion-sensitizing gradients, so freely diffusing water loses more signal, increasing lesion conspicuity for restricted diffusion.

Question 189: Which of the following precautions is required before administering a GBCA to a breastfeeding mother, according to ACR recommendations?

No precautions are required as only trace amounts enter breast milk (Correct answer)
The infant must receive a blood test before the mother can resume breastfeeding
Breastfeeding should be interrupted for 24–48 hours after GBCA administration
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 190: On diffusion-weighted MRI (DWI), an acute ischemic infarct typically shows:

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

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

Increasing NEX
Decreasing the matrix size
Increasing slice thickness
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 192: Which ligament of the knee is best seen on sagittal MRI images and connects the posterior femur to the anterior tibia?

Medial collateral ligament
Anterior cruciate ligament (Correct answer)
Posterior cruciate ligament
Arcuate 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 193: What is the primary source of acoustic noise in an MRI scanner?

The radiofrequency transmitter coil vibrating
Cryogenic helium boil-off
The rotating fan of the RF amplifier
Rapid switching of gradient coils within the static magnetic field (Correct answer)

Correct answer: Rapid switching of gradient coils within the static magnetic field

Lorentz forces act on gradient coil conductors carrying rapidly switched currents within B0, causing coil vibration and the characteristic loud knocking noise.

Question 194: MR Conditional implants are safe to scan only when:

The radiologist approves verbally
The scan time is under 30 minutes
The patient gives verbal consent
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 195: 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, low ADC
Low signal on DWI, high 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 196: What is the effect of increasing the echo time (TE) on T2-weighted images?

Decreases T2 weighting by increasing signal
Has no effect on tissue contrast
Increases T1 weighting
Increases T2 weighting by allowing more transverse relaxation (Correct answer)

Correct answer: Increases T2 weighting by allowing more transverse relaxation

A longer TE allows more time for T2 decay, so tissues with short T2 lose more signal, increasing contrast between tissues with different T2 values.

Question 197: Which MRI sequence is used to visualize flowing blood as bright signal ('bright blood') without contrast injection by exploiting the inflow of unsaturated spins into the imaging slice?

Time-of-flight (TOF) MRA (Correct answer)
Phase contrast MRA
VIBE
Contrast-enhanced MRA

Correct answer: Time-of-flight (TOF) MRA

TOF MRA uses gradient echo with short TR to saturate stationary tissue; fresh unsaturated blood flowing into the slice appears bright due to the inflow enhancement effect.

Question 198: IV line tubing and monitoring cables used inside the MRI suite must be:

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

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

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

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

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

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

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

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 202: Following an RF burst, protons will

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

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 203: Which MRI contrast agent class is associated with the highest risk of nephrogenic systemic fibrosis (NSF)?

Linear non-ionic agents (Correct answer)
Manganese-based agents
Macrocyclic ionic agents
Blood pool agents

Correct answer: Linear non-ionic agents

Linear non-ionic (and some linear ionic) gadolinium agents release free Gd³⁺ more readily and carry the highest NSF risk in patients with severe renal impairment.

Question 204: What does the term 'repetition time' (TR) refer to in MRI pulse sequences?

The total scan duration
The time for magnetization to return to equilibrium after T2 decay
The time between the RF pulse and the echo
The time between successive RF excitation pulses applied to the same slice (Correct answer)

Correct answer: The time between successive RF excitation pulses applied to the same slice

TR is the interval between the beginning of one RF excitation pulse and the beginning of the next for the same slice, controlling T1 contrast.

Question 205: Balanced steady-state free precession (SSFP) sequences have an advantage over conventional GRE sequences.

To navigate k-space, use gradients of alternating magnetic fields.
Employ gradient spoilers to lessen transverse magnetization
To create spin echoes, hold onto your transverse magnetization. (Correct answer)
To create spin echoes, use 180-degree pulses.

Correct answer: To create spin echoes, hold onto your transverse magnetization.

Balanced steady-state free precession (bSSFP) sequences have a key advantage over conventional spoiled GRE sequences by actively preserving transverse magnetization from previous excitations. Unlike spoiled GREs that use spoiler gradients to eliminate residual transverse magnetization, bSSFP sequences are designed to maintain both longitudinal and transverse magnetization in a steady state. This allows for the formation of both FID and echo signals, leading to high signal-to-noise ratio and characteristic T2/T1 contrast.

Question 206: The anterior and posterior horns of the lateral ventricles are best evaluated for periventricular leukomalacia (PVL) on which MRI plane?

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

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 207: What is the primary reason gradient coils produce loud acoustic noise during MRI scanning?

Lorentz forces cause the gradient coil windings to physically vibrate as current rapidly switches (Correct answer)
Cryogen boiling creates mechanical vibration in the magnet bore
The patient table motor produces noise as it moves into position
RF pulses vibrate the RF coil housing

Correct answer: Lorentz forces cause the gradient coil windings to physically vibrate as current rapidly switches

Rapidly switching electrical current in gradient coils within the strong static field produces Lorentz forces that physically deflect the coils, generating loud knocking sounds.

Question 208: When should a technologist notify the supervising radiologist or radiologist immediately during an MRI exam?

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

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 209: During inversion recovery, the null point (TI) for fat suppression (STIR) is set to:

TI = TR / 2
TI = TE × T1(fat)
TI = T1(fat) × ln(2) (Correct answer)
TI = T2(fat) × 0.693

Correct answer: TI = T1(fat) × ln(2)

The null point occurs when the recovering longitudinal magnetization of fat passes through zero, which is at TI ≈ T1(fat) × ln(2) ≈ 0.693 × T1(fat).

Question 210: Bilateral symmetric T2 hyperintensity in the basal ganglia of a child is most associated with which condition?

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

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

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

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 212: In MRI, what does the term 'bandwidth' typically refer to in clinical practice?

The RF pulse duration in milliseconds
The range of flip angles used in a sequence
The number of phase-encode steps acquired
The range of frequencies sampled during readout, affecting SNR and chemical shift (Correct answer)

Correct answer: The range of frequencies sampled during readout, affecting SNR and chemical shift

Receiver bandwidth is the range of frequencies digitized during readout; wider bandwidth reduces chemical shift and distortion but decreases SNR.

Question 213: On a sagittal MRI of the cervical spine, the posterior longitudinal ligament appears as a thin structure along which surface of the vertebral bodies?

Superior
Anterior
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 214: 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 215: The landmark for centering an MRI brain exam using a head coil is located at:

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

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 216: Which safety zone in an MRI facility is defined as the area that requires screening and controlled access due to the fringe magnetic field?

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

Correct answer: Zone III

Zone III is the area where the fringe field poses risk and requires restricted access; only screened individuals may enter.

Question 217: For pituitary gland MRI, which plane is considered the primary imaging plane?

Axial
Coronal (Correct answer)
Oblique axial
Sagittal

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

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

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 219: In contrast to SE, GRE sequences employ

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

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 220: When performing MR arthrography of the hip, the patient is typically positioned with the hip in which orientation?

30° internal rotation
Neutral or slight internal rotation (Correct answer)
Maximum external rotation
Frog-leg lateral position

Correct answer: Neutral or slight internal rotation

Neutral to slight internal rotation during hip MR arthrography places the femoral neck parallel to the imaging plane and optimizes labral visualization.

Question 221: The 'magic angle' artifact in MRI tendons occurs at approximately what angle relative to the main magnetic field?

55° (Correct answer)
15°
30°
45°

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

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

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 223: 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
External RF interference from inadequate shielding or open RF cage door (Correct answer)
Gradient switching noise

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

Long TR, short TE
Long TR, long TE (Correct answer)
Short TR, short TE
Short TR, long 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 225: 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.

Paramagnetic
Superpapmagnetic
Ferromagnetic (Correct answer)
Diamagnetic

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 226: 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 227: 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 228: What term describes an object becoming a high-speed projectile when brought near a strong MRI magnetic field?

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

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 229: Which of the following is the correct management for a patient who experiences an acute severe allergic-like reaction (anaphylaxis) following GBCA injection?

Administer IV saline bolus only
Administer 50 mg IV diphenhydramine and continue scan
Administer oral Benadryl and observe for 15 minutes
Stop contrast injection, call code team, administer epinephrine 0.3 mg IM (1:1000) (Correct answer)

Correct answer: Stop contrast injection, call code team, administer epinephrine 0.3 mg IM (1:1000)

Anaphylaxis requires immediate cessation of injection, emergency team activation, and epinephrine 0.3 mg IM (1:1000 concentration) in the lateral thigh as first-line treatment.

Question 230: On the ARRT MRI registry exam, which content area covers patient care, contrast agents, and MRI safety screening?

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

Correct answer: Patient Care and Education

Patient Care and Education encompasses screening, safety, contrast administration, and patient communication topics.

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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