ARRT MRI Exam — Questions and Answers

Question 1: For temporomandibular joint (TMJ) MRI, images are obtained with the jaw in which two positions?

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

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

Diamagnetic
Paramagnetic (Correct answer)
Superpapmagnetic
Ferromagnetic

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

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 4: The b-value in diffusion-weighted imaging controls the degree of diffusion weighting. Increasing the b-value:

Increases diffusion contrast but decreases SNR (Correct answer)
Has no effect on image quality
Decreases T2 contribution
Increases overall image SNR

Correct answer: Increases diffusion contrast but decreases SNR

Higher b-values provide greater diffusion contrast by increasing the dephasing of mobile water protons, but at the cost of reduced SNR due to greater signal attenuation from all spins.

Question 5: What is the Larmor frequency in MRI?

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

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

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

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

Superpapmagnetic
Ferromagnetic (Correct answer)
Diamagnetic
Paramagnetic

Correct answer: Ferromagnetic

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

Question 8: During inversion recovery, the null point (TI) for fat suppression (STIR) is set to:

TI = TE × T1(fat)
TI = T1(fat) × ln(2) (Correct answer)
TI = TR / 2
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 9: For a brain MRI, which standard plane best demonstrates the corpus callosum in its entirety?

Sagittal (Correct answer)
Axial
Coronal
Oblique

Correct answer: Sagittal

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

Question 10: Which MRI sequence is most commonly used for evaluating liver lesions using T2 contrast with heavy T2 weighting for the bile ducts?

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

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

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

Question 11: What is the effect of increasing the number of signal averages (NSA/NEX) on MRI image quality?

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

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

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

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 13: 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
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)
Increase the number of slices

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

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

Correct answer: Ankle positioning block or foam wedge

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

Question 15: Gadolinium contrast extravasation at the IV injection site is classified as which type of adverse event?

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

Correct answer: Local injection site reaction (extravasation)

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

Question 16: What is the primary advantage of using a higher-relaxivity GBCA (e.g., gadobenate dimeglumine) compared to a standard-relaxivity agent?

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

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

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

Question 17: 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 18: When should a technologist notify the supervising radiologist or radiologist immediately during an MRI exam?

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

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

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

Question 19: 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, low ADC (Correct answer)
High signal on DWI, high ADC
Low signal on DWI, high ADC
Low signal on DWI, low ADC

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

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

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

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

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

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

Question 22: What is the function of the shim coils in an MRI system?

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

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

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

Correct answer: Implants and devices section

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

Question 24: Which MRI artifact is caused by periodic patient motion such as cardiac or respiratory movement?

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

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

Contrast agent uptake rate in tissue
Rate of image data acquisition in k-space
Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass (Correct answer)
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 26: Which patient positioning accessory is routinely used to reduce hand and wrist movement during an MRI wrist examination?

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

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

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

Question 27: FLAIR (Fluid-Attenuated Inversion Recovery) suppresses which signal and is most useful for detecting:

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

Correct answer: CSF signal; periventricular and cortical lesions

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

Question 28: The gradient subsystem's primary goal is to

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

Correct answer: Everything mentioned

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

Question 29: What sound pressure level (dB) can MRI gradient noise reach, necessitating hearing protection for patients?

130–140 dB
99–115 dB (Correct answer)
60–70 dB
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 30: The term 'T1 mapping' in cardiac MRI using gadolinium is used to quantify which clinically important tissue property?

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

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

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

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

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

Correct answer: Patient Care and Education

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

Question 33: Which structure in the knee joint is best evaluated with MRI and appears as a low-signal-intensity triangular structure?

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

Correct answer: Medial meniscus

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

Question 34: Magnets formed of ferrous material found naturally or from blocks or slabs.

Permanent (Correct answer)
Selenoid
Reistive
Superconducting

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 35: What is the primary advantage of a 3T MRI scanner compared to a 1.5T scanner?

Shorter T1 relaxation times for all tissues
Lower SAR deposition in patients
Elimination of susceptibility artifacts
Higher SNR that can be traded for faster scans or higher spatial resolution (Correct answer)

Correct answer: Higher SNR that can be traded for faster scans or higher spatial resolution

Field strength doubling theoretically doubles SNR, which can be reinvested in thinner slices, smaller voxels, or reduced scan time.

Question 36: 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 radiation therapy
Hold a primary ARRT certification in nuclear medicine technology
Hold an associate degree only with no primary ARRT credential (Correct answer)

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

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

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

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

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 39: Cardiac MRI uses which technique to synchronize data acquisition with the cardiac cycle and minimize cardiac motion artifact?

Real-time imaging without synchronization
ECG gating or cardiac triggering (Correct answer)
Respiratory gating only
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 40: What happens to image contrast when the echo time (TE) is increased in a T2-weighted sequence?

T2 contrast increases as tissues with short T2 decay faster (Correct answer)
T1 contrast increases
Tissues appear uniformly bright
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 41: The quantity of determines the receiver bandwidth.

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

Correct answer: Frequency samples in the matrix

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

Question 42: On MRI, cortical bone appears as which signal intensity on both T1 and T2 weighted images?

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

Correct answer: Low signal (signal void)

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

Question 43: The apparent diffusion coefficient (ADC) map is calculated to eliminate which confounding effect in DWI?

T2 shine-through (Correct answer)
Chemical shift misregistration
T1 recovery
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 44: On a sagittal MRI of the cervical spine, the posterior longitudinal ligament appears as a thin structure along which surface of the vertebral bodies?

Anterior
Superior
Posterior (Correct answer)
Lateral

Correct answer: Posterior

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

Question 45: Which parameter, when increased, will most directly improve the signal-to-noise ratio (SNR) in an MRI image?

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

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 46: In MRI, what is k-space?

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

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

1 / (TR × TE)
Flip angle / repetition time
Voxel volume × √(NEX) × √(scan time factors) (Correct answer)
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 48: A technologist who holds an RT(MR)(ARRT) credential and allows it to lapse must complete which process to reinstate it?

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

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

Volume coil
Body coil
Quadrature head 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 50: What does k-space represent in MRI?

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

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

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

Question 51: Which of the following best describes the 'magic angle' artifact and at what angle it occurs?

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

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

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

Question 52: Bilateral symmetric T2 hyperintensity in the basal ganglia of a child is most associated with which condition?

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

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

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

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 54: 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?

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

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

100
220
175 (Correct answer)
200

Correct answer: 175

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

Question 56: MR spectroscopy (MRS) of the brain measures metabolite concentrations. Which metabolite, reduced in neuronal loss and gliosis, is considered a marker of neuronal integrity?

Creatine (Cr)
N-acetylaspartate (NAA) (Correct answer)
Choline (Cho)
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 57: What is the effect of reducing the number of phase-encoding steps while keeping FOV and frequency steps constant?

Through-plane resolution is affected
SNR improves and scan time increases
Frequency-direction resolution decreases
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 58: The range of frequencies sampled during the process is represented by the receiver bandwidth.

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

Correct answer: gradient of frequency encoding

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

Question 59: 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 60: A T1 hyperintense (bright) lesion in the brain is most consistent with which finding?

Subacute blood or fat-containing lesion (Correct answer)
Vasogenic edema
Pure fluid-filled cyst
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 61: Diffusion tensor imaging (DTI) and tractography are primarily used to evaluate which brain structure?

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

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

5 meters
1 meter
3 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 63: Which section of the ARRT MRI content specifications covers pulse sequence selection and acquisition parameter optimization?

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

Correct answer: Image Production

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

Question 64: In MRI safety, what is the specific absorption rate (SAR)?

The static field strength absorbed by implants
The rate of acoustic energy deposited in tissue
The rate of gradient switching measured in T/m/s
The rate of RF energy absorbed per unit mass of tissue, measured in W/kg (Correct answer)

Correct answer: The rate of RF energy absorbed per unit mass of tissue, measured in W/kg

SAR measures RF power deposition in tissue; regulatory limits exist to prevent tissue heating, especially important at higher field strengths and with certain sequences.

Question 65: 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 66: Which of the following best describes the purpose of placing the frequency-encoding gradient in the anterior-posterior direction for spine MRI?

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

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

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

Question 67: Which MRI technique is used to assess brain perfusion by tracking the first pass of a gadolinium bolus?

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

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

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

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 69: 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
Known pregnancy, especially first trimester (Correct answer)
Mild hypertension controlled with oral medication
Known diabetes mellitus

Correct answer: Known pregnancy, especially first trimester

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

Question 70: Which ARRT resource provides the official list of examination content categories, subcategories, and approximate percentage weighting for the MRI registry exam?

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

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 71: A small bandwidth makes _slices possible.

Slimmer (Correct answer)
Dicker

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 72: A patient with a cochlear implant is scheduled for MRI. What is the primary concern?

Device displacement or demagnetization by the static field and RF heating (Correct answer)
Heating of the cochlear fluid
Claustrophobia from the device signal
Acoustic noise damage

Correct answer: Device displacement or demagnetization by the static field and RF heating

Cochlear implants contain magnets that can torque, displace, or demagnetize in the MRI field, posing significant safety risks.

Question 73: Which MRI sequence is best suited for evaluating articular cartilage because it provides excellent contrast between cartilage, fluid, and bone?

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

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

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

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 75: 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)
Susceptibility differences between tissues; phase-encode direction
B1 field inhomogeneity; slice-select direction
T1 differences between tissues; readout 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 76: A candidate applying for the ARRT MRI registry via the post-primary pathway must hold a primary ARRT certification in which of the following disciplines?

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

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

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

Question 77: What is the recommended action when a patient with an unknown metallic implant cannot be identified before a clinically urgent MRI?

Consult the radiologist and ordering physician to assess risk vs. benefit (Correct answer)
Cancel the exam without exception
Proceed with the scan at lowest SAR
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 78: When imaging the lumbar spine, which position best opens the intervertebral foramina and reduces lumbar lordosis for improved visualization?

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

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

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

Question 79: Which of the following best describes the concept of signal-to-noise ratio (SNR) in MRI?

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

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

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

Question 80: Which of the following changes will increase spatial resolution without changing the FOV?

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

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

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

Correct answer: Body (volume) coil

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

Question 82: 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 aligned with the main magnetic field
Voxel that produces equal signal in T1 and T2 sequences

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

Z
X (Correct answer)
Y

Correct answer: X

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

Question 84: Which of the following maneuvers most directly reduces chemical shift artifact of the first kind?

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

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

Increase slice thickness
Decrease the matrix size
Increase the repetition time (TR)
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 86: On brain MRI, the hippocampus is best evaluated for atrophy (as in Alzheimer's disease) on which plane?

Oblique axial
Sagittal only
Coronal, especially perpendicular to the long axis of the hippocampus (Correct answer)
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 87: Continuing education (CE) requirements for ARRT MRI credential renewal are completed over what cycle length?

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

Correct answer: 2 years

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

Question 88: What is the primary trade-off when reducing the field of view (FOV) in MRI?

Increased slice coverage with same resolution
Improved spatial resolution but increased risk of aliasing artifacts (Correct answer)
Improved SNR with no change in resolution
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 89: Which of the following best explains why a phased-array coil improves SNR compared to a body coil?

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

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

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

Question 90: The landmark for centering an MRI brain exam using a head coil is located at:

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

Correct answer: Nasion or bridge of the nose

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

Question 91: 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)
Diffusion-weighted imaging
STIR fat suppression
MR spectroscopy

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 92: 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
Superior mesenteric artery
Femoral artery
Abdominal aorta or descending thoracic aorta at the level of interest (Correct answer)

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

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

Question 93: Which MRI zone is defined as the area containing the MRI scanner itself where the static magnetic field is always present?

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

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 94: 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?

Choline (Cho) (Correct answer)
Lactate
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 95: Which of the following is a documented risk of MRI during the first trimester of pregnancy?

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

Correct answer: All of the above except ionizing radiation

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

Question 96: What is the main biological risk associated with rapidly switching gradient magnetic fields during an MRI scan?

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

Correct answer: Peripheral nerve stimulation

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

Question 97: SSFP (steady-state free precession) sequences such as TrueFISP/FIESTA produce contrast that is proportional to which tissue property ratio?

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

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

High natural abundance and large magnetic moment (Correct answer)
Low atomic mass and zero spin
High atomic number and radioactivity
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 99: What is the purpose of crusher (spoiler) gradients in a spin echo sequence?

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

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

The time for magnetization to return to equilibrium after T2 decay
The total scan duration
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 101: Which parameter directly controls the degree of T2 weighting in a spin echo sequence?

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

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

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

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

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

Question 103: Which coil type provides the highest signal-to-noise ratio (SNR) for imaging small superficial structures such as the wrist?

Body coil
Dedicated extremity or surface coil (Correct answer)
Phased-array spine coil
Head coil

Correct answer: Dedicated extremity or surface coil

Dedicated extremity or surface coils placed close to the anatomy maximize SNR by minimizing the receive volume to the region of interest.

Question 104: Which of the following is the most effective method to reduce motion artifact from bowel peristalsis in abdominal MRI?

Use a larger FOV
Increase TR
Administer an antiperistaltic agent such as glucagon (Correct answer)
Apply saturation bands inferior to the 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 105: What does a high b-value in diffusion-weighted imaging (DWI) indicate?

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

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 106: Following an RF burst, protons will

As per T2*, recover along B0, and thereafter dephase in accordance with T1.
As per T2*, dephase in accordance with T1 and then recover along B0.
Dephase in accordance with T2*, then recover in accordance with T1 along B0. (Correct answer)
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 107: Which ligament of the knee is best seen on sagittal MRI images and connects the posterior femur to the anterior tibia?

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

Correct answer: Anterior cruciate ligament

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

Question 108: Magnetization transfer contrast (MTC) in MRI is based on the exchange of magnetization between which two proton pools?

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

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

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

Correct answer: MR Safe

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

Question 110: What is the relationship between magnetic field strength (B0) and the Larmor frequency?

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

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 111: Which MRI technique uses magnetically labeled water protons as an endogenous tracer to measure cerebral blood flow without contrast injection?

Dynamic Susceptibility Contrast (DSC) MRI
Dynamic Contrast Enhanced (DCE) MRI
Blood Oxygen Level Dependent (BOLD) fMRI
Arterial Spin Labeling (ASL) (Correct answer)

Correct answer: Arterial Spin Labeling (ASL)

ASL uses RF inversion of arterial water protons proximal to the imaging plane as a flow tracer, enabling non-invasive perfusion measurement.

Question 112: 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 high, T2 high, with peripheral enhancement
T1 high, T2 low
T1 low, T2 low

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

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

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

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

Correct answer: High signal on DWI and low ADC values

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

Question 115: Which inversion recovery technique is used to suppress fat signal in musculoskeletal MRI?

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

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 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
Passing a vendor-specific MRI operations test
Completion of a formal coursework curriculum covering MRI physics, procedures, and patient care (Correct answer)
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: What is the effect of increasing receiver bandwidth on MRI image quality?

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

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 118: 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.

Slew rate (Correct answer)
Coil configuration
Rise time

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

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

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

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

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

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

Question 121: In dynamic contrast-enhanced (DCE) MRI of the breast, which kinetic enhancement curve pattern is most concerning for malignancy?

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

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

Prone with the breasts in a dedicated bilateral breast coil (Correct answer)
Upright in a dedicated open MRI
Lateral decubitus with the ipsilateral breast dependent
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 123: Which artifact arises when signal from outside the FOV wraps around to the opposite side of the image?

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

Correct answer: Aliasing (wrap-around) artifact

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

Question 124: A patient with a metallic foreign body in the eye should be evaluated with which imaging modality BEFORE entering the MRI suite?

PET scan
CT scan (Correct answer)
Bone scan
Ultrasound

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

Resistive magnet
Selenoid magnet (Correct answer)
Permanent magnet
Superconducting

Correct answer: Selenoid magnet

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

Question 126: 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
BOLD fMRI
Arterial spin labeling (ASL) (Correct answer)
Phase contrast MRI

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

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

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

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 129: Which gradient is primarily responsible for frequency encoding in MRI?

Readout gradient (Correct answer)
Slice-select gradient
Spoiler gradient
Phase-encoding 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 130: In contrast to SE, GRE sequences employ

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

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

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

Correct answer: Group III (macrocyclic)

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

Question 132: 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)
MR arthrography and spectroscopy
STIR and inversion recovery sequences

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

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

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 134: Which MRI phenomenon occurs when protons at the boundary of fat and water tissues experience a frequency offset, causing a dark or bright band?

Magnetic susceptibility artifact
Gibbs ringing
Chemical shift artifact (Correct answer)
Wraparound (aliasing) artifact

Correct answer: Chemical shift artifact

Chemical shift artifact results from the ~3.5 ppm frequency difference between fat and water protons, causing spatial misregistration along the frequency-encode direction.

Question 135: In MR imaging, the signal-to-noise ratio (SNR) improves with increasing field strength approximately as:

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

Correct answer: Linearly (proportional to B0)

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

Question 136: Chemical shift artifact of the first kind occurs at interfaces between fat and water and manifests as:

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
Signal voids around metallic implants

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

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

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

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

Question 138: During an MRI exam, a patient begins experiencing intense burning sensations on their skin near monitoring cables. What is the most likely cause?

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

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

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

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

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

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

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

Correct answer: MR Unsafe

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

Question 142: 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.

Quadrature (Correct answer)
Vertical
Phased array
Helmholtz pair

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

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

Correct answer: Phase direction on gradient-echo sequences

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

Question 144: The magnetic field's intensity is varied from head to foot by this gradient coil.

Y
Z (Correct answer)
X

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

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

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

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

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

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

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

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

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

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

Question 149: The ARRT MRI registry exam content specification places approximately what percentage of questions in the 'Procedures' domain?

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

Correct answer: 35%

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

Question 150: In a spin-echo sequence, which combination of TR and TE produces a T2-weighted image?

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

Correct answer: Long TR, long TE

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

Question 151: Pulsatile flow artifact from a vessel typically appears as ghost images displaced in which direction?

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

Correct answer: Phase-encoding direction

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

Question 152: Which MRI contrast agent class is associated with the highest risk of nephrogenic systemic fibrosis (NSF)?

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

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

Passive (Correct answer)
Active

Correct answer: Passive

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

Question 154: EPI (echo planar imaging) sequences are particularly prone to which artifact caused by off-resonance spins accumulating phase during the long readout?

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

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 155: Traditional GRE order

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

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

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

Question 156: In MRI, the term 'flip angle' refers to:

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

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

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

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

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

Question 158: Which MRI protocol modification is used to evaluate the acetabular labrum of the hip with maximum sensitivity for tears?

MR arthrography with intra-articular gadolinium dilution (Correct answer)
Diffusion-weighted imaging of the hip
T1 fat-saturated without contrast
Standard T2 FSE 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 159: On a coronal MRI of the knee, which structure appears as a low-signal C-shaped band along the tibial plateau?

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

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

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

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 161: What is the primary purpose of fat saturation techniques in MRI?

To reduce T1 relaxation time of fat
To suppress the fat signal so adjacent structures are more conspicuous (Correct answer)
To eliminate chemical shift artifact entirely
To increase the signal from fat-containing tissues

Correct answer: To suppress the fat signal so adjacent structures are more conspicuous

Fat saturation applies a frequency-selective RF pulse to null the fat signal, improving visibility of adjacent enhancing or edematous tissue.

Question 162: What document must candidates agree to when submitting an ARRT MRI registry application?

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

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

Axial
Oblique
Coronal
Sagittal (Correct answer)

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

Applying a gradient to transfer magnetization between slices
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

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

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

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

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

Question 166: 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 167: What differentiates T2 from T2* is

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

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 168: Which MRI sequence is most sensitive to hemorrhage detection because of its sensitivity to blood products?

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

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

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

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 170: 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)
Gadopentetate dimeglumine (Magnevist)
Gadobutrol (Gadavist)

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

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

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

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

Question 172: What does the acronym STIR stand for, and what tissue does it primarily null?

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

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

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

Question 173: 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 difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue (Correct answer)
The ratio of gadolinium dose to body weight

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

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

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

Resistive magnet
Superconducting (Correct answer)
Selenoid magnet
Permanent 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 176: What is the effect of increasing the echo time (TE) on T2-weighted images?

Increases T1 weighting
Decreases T2 weighting by increasing signal
Has no effect on tissue contrast
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 177: What is the main advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

Improved SNR by adding signals from multiple coils
Increased spatial resolution without penalty
Elimination of susceptibility artifacts
Reduced acquisition time by undersampling k-space using multiple coil elements (Correct answer)

Correct answer: Reduced acquisition time by undersampling k-space using multiple coil elements

Parallel imaging uses the spatial sensitivity profiles of phased-array coils to reconstruct missing k-space lines, allowing faster acquisitions at the cost of some SNR.

Question 178: The 'magic angle' artifact in MRI tendons occurs at approximately what angle relative to the main magnetic field?

15°
30°
55° (Correct answer)
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 179: A pregnant MRI technologist should follow which guideline regarding working in the MRI suite?

Avoid all scanner rooms during pregnancy
Wear a lead apron to reduce MRI exposure
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)

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

Sagittal
Axial
Oblique axial
Coronal (Correct answer)

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 181: For MRI of the knee, the standard patient position is:

Knee extended in slight external rotation (5–15°), patient supine in dedicated knee coil (Correct answer)
Knee hyperflexed, patient lateral
Knee flexed 45°, patient supine without coil
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 182: What is the primary source of acoustic noise in an MRI scanner?

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

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 183: Which of the following parameters most directly controls T1 contrast in a spin echo sequence?

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

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 184: The ARRT MRI exam content category 'Procedures' would most likely include a question about which topic?

Brain MRI protocol selection for stroke evaluation (Correct answer)
Larmor frequency calculations
Cryogen quench valve operation
Patient screening form design standards

Correct answer: Brain MRI protocol selection for stroke evaluation

Procedures covers clinical protocols such as selecting the appropriate MRI protocol for specific pathologies.

Question 185: The anterior and posterior horns of the lateral ventricles are best evaluated for periventricular leukomalacia (PVL) on which MRI plane?

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

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

FOURIER TRANSFORM
FID
CHEMICAL SHIFT (Correct answer)
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 187: In MRI of the breast, a finding described as a 'rim-enhancing mass' on dynamic contrast imaging is most suspicious for:

Fibroadenoma
Malignant lesion (Correct answer)
Fat necrosis
Simple cyst

Correct answer: Malignant lesion

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

Question 188: What is the relationship between voxel size and SNR in MRI?

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

Correct answer: Larger voxels produce higher SNR

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

Question 189: Which MRI sequence is most sensitive for detecting early bone marrow edema in stress fractures?

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

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 190: Gibbs (truncation) artifact is caused by:

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
Aliasing from a FOV smaller than the patient

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 191: The flip angle in an MRI sequence refers to which of the following?

The angular velocity of proton precession
The angle of the main magnetic field relative to the bore
The tilt of the gradient coil axis
The degree to which the net magnetization vector is rotated from B0 by the RF pulse (Correct answer)

Correct answer: The degree to which the net magnetization vector is rotated from B0 by the RF pulse

The flip angle is how far the net magnetization vector is tipped away from the longitudinal axis by the RF pulse.

Question 192: Which organization accredits MRI education programs whose graduates may be eligible to sit for the ARRT MRI registry?

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

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

Axial (Correct answer)
Sagittal oblique
Oblique coronal
Coronal

Correct answer: Axial

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

Question 194: When performing MRI on a patient with an insulin pump, which step is essential before beginning the exam?

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

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

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

Question 195: 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 a prior misdemeanor conviction on record (Correct answer)
Candidate has exceeded the CE deadline by one week

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

Susceptibility effect
Missile effect (Correct answer)
Gradient artifact
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 197: 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 198: In a spin echo (SE) sequence, increasing the repetition time (TR) while keeping TE short primarily results in:

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

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

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

Question 199: A patient reports a prior allergic-like reaction to a GBCA. Which of the following is the recommended premedication protocol?

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

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

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

Question 200: Which gradient-echo sequence uses a very short TR and a spoiler gradient to eliminate residual transverse magnetization before the next RF pulse?

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

Correct answer: Spoiled gradient echo (SPGR/FLASH)

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

Question 201: A 'blooming' artifact on gradient echo (GRE) MRI is caused by which substance?

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

Correct answer: Hemosiderin or calcification

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

Question 202: Which MRI artifact appears as a ghosting or smearing of bright structures in the phase-encoding direction?

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

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

Active (Correct answer)
Passive

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 204: Which type of MRI coil provides the best SNR for imaging a small, superficial structure?

Small surface coil placed directly over the region of interest (Correct answer)
Solenoid body coil at isocenter
Large volume (birdcage) coil surrounding the patient
Phased-array coil designed for the spine

Correct answer: Small surface coil placed directly over the region of interest

A small surface coil placed close to the target anatomy maximizes signal reception from that area while minimizing noise from surrounding regions.

Question 205: Magnetization transfer (MT) contrast in MRI works by selectively saturating which proton pool?

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

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

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

Question 206: What is the primary reason gradient coils produce loud acoustic noise during MRI scanning?

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

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

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

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 208: Wraparound (aliasing) artifact in MRI is caused by:

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

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

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

Question 209: Which technique is most effective for reducing susceptibility artifact from a metallic implant in MRI?

Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth (Correct answer)
Increase TE
Use a gradient-echo sequence
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 210: Spin echo sequence is modified by rapid spin echo sequence by

Adding 180-degree pulses in succession (Correct answer)
Adding repeated pulses of 90 degrees
Gradient additions for spoilers
progressively adding gradients encoded with frequencies

Correct answer: Adding 180-degree pulses in succession

The rapid spin echo (also known as Fast Spin Echo or Turbo Spin Echo) sequence modifies the conventional spin echo by applying a train of multiple 180-degree refocusing pulses after a single 90-degree excitation pulse. Each 180-degree pulse generates a separate echo, allowing multiple lines of k-space to be acquired within a single TR period. This significantly shortens scan times compared to conventional spin echo sequences.

Question 211: Which ARRT exam content domain addresses gradient performance, field homogeneity, and RF coil function?

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

Correct answer: Physics and Instrumentation

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

Question 212: Which type of question format is exclusively used on the ARRT MRI registry computer-based examination?

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

Correct answer: Multiple choice with one best answer

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

Question 213: A 'corduroy' or 'herringbone' artifact covering the entire image is most often caused by:

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

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 214: T2* relaxation differs from T2 relaxation primarily because T2* includes:

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

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

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

Question 215: What is the purpose of applying a saturation band in MRI?

To improve spatial resolution in the phase direction
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

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

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

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

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

Question 217: A technologist wants to reduce chemical shift artifact at the fat-water interface. Which parameter change is most appropriate?

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

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 218: 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
External RF interference from inadequate shielding or open RF cage door (Correct answer)
Gradient switching noise
Patient movement

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

Quadrature
Phased array (Correct answer)
Vertical
Helmholtz pair

Correct answer: Phased array

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

Question 220: What score does ARRT use to determine passing on the MRI registry examination?

A raw score of 75%
A criterion-referenced passing standard set by content experts (Correct answer)
A norm-referenced score based on the current testing cohort
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 221: Which of the following precautions is required before administering a GBCA to a breastfeeding mother, according to ACR recommendations?

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

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 222: Gibbs ringing artifact is caused by:

RF pulse imperfections
Chemical shift between fat and water
Motion during phase encoding
Truncation of k-space data at high spatial frequencies (Correct answer)

Correct answer: Truncation of k-space data at high spatial frequencies

Gibbs ringing (truncation artifact) occurs when k-space is sampled with insufficient high-frequency data, causing oscillating bands near sharp tissue interfaces.

Question 223: 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 224: MR Conditional implants are safe to scan only when:

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

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 225: Fast spin echo sequences, in contrast to spin echo, have

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

Correct answer: T2 weighting increased but susceptibility decreased

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

Question 226: When is a candidate's ARRT MRI registry exam score report typically available?

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

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

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

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

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

Question 228: Multiple sclerosis (MS) plaques in the brain are classically found in which location on MRI?

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

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

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

Question 229: What is the primary consequence of using a high acceleration factor in parallel imaging?

Increased spatial resolution
Improved T1 contrast
Reduced scan time with no image quality loss
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 230: 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 Conditional (Correct answer)
MR Safe
MR Unsafe

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.

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%

To Pass

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