CAMRT MRI Exam: Professional Practice and Ethics

Domain 1: Professional Practice and Ethics

The CAMRT MRI examination tests professional conduct as rigorously as technical skill. This domain covers scope of practice, informed consent, privacy, accountability, and equity in care. Questions often present a realistic dilemma and ask for the next or best action.

Core rules and concepts

Scope of practice. An MRI technologist performs and optimizes the examination; interpretation and diagnosis belong to the radiologist. You may describe what the protocol is designed to assess, but not what the image shows.
Informed consent. Consent must be voluntary, informed, and documented. A signed requisition is not consent. Patients may withdraw consent at any time, including mid-scan.
Privacy and confidentiality. In Canada, PHIPA (Ontario) or PIPEDA and provincial health statutes govern personal health information. Use the minimum necessary information, lock screens, and never photograph images with a personal device.
Accountability. Follow the CAMRT Code of Ethics; report errors and near misses through the facility's incident system; maintain competence through continuing education.
Cultural safety and equity. Use qualified interpreters, offer trauma-informed positioning and communication, and recognize barriers such as transport, language, and past negative healthcare experiences.

Worked example

A patient asks, "Did the scan show cancer?" The technologist has seen a large enhancing mass.

Best response: acknowledge the question, explain that the radiologist will interpret the images and that the ordering physician will discuss results, and document that the patient asked. Do not confirm, deny, or hint at the finding. The reasoning is scope: image interpretation is outside the technologist's role, and premature disclosure can harm the patient and the care pathway. If the patient is distressed, involve the radiologist or referring team promptly.

Traps that cost marks

Choosing "tell the patient what you saw" because it seems compassionate.
Treating a requisition or verbal "okay" as sufficient consent for contrast.
Discussing a case in an elevator or on social media, even without a name.
Assuming a patient understands English because they nodded; use an interpreter.

Key points

No diagnosis or image interpretation by the technologist.
Consent is a process, not a signature.
Privacy applies to images, reports, and conversations.

Patient Care and Communication

Domain 2: Patient Care and Communication

This domain tests safe, person-centred care across the MRI pathway: pre-screening, preparation, contrast administration, monitoring, and post-procedure follow-up. Exam items often hinge on whether you identified a contraindication or a care need before the patient entered the magnet room.

Core rules and concepts

Systematic screening. Screen for implants, foreign bodies, pregnancy, renal function, allergies, claustrophobia, pain, and ability to lie still. Re-screen if the patient's history changes.
Gadolinium-based contrast agents (GBCAs). Check eGFR in patients with known renal disease, diabetes, or age >60 per policy. Avoid linear agents in severe renal impairment (eGFR <30) because of nephrogenic systemic fibrosis (NSF) risk; use a macrocyclic agent at the lowest diagnostic dose if contrast is essential.
Pregnancy and lactation. MRI without contrast is generally preferred when clinically justified. Gadolinium crosses the placenta; use only if essential. Lactation does not require interruption for most agents, but follow local policy.
Anxiety and claustrophobia. Offer headphones, eye masks, prone or feet-first positioning, a companion where safe, and a panic button. Sedation requires monitoring and an appropriate escort.
Monitoring and adverse events. Recognize allergic-like reactions, extravasation, and vasovagal responses. Stop injection, assess, call for help, and document.

Worked example

A 68-year-old with diabetes has an order for MRI with a linear gadolinium agent. eGFR is 25 mL/min/1.73 m².

Reasoning: eGFR <30 places the patient at risk for NSF with linear agents. The technologist should not simply proceed. Contact the radiologist: confirm whether contrast is essential, switch to a macrocyclic agent, use the lowest dose, and document the risk discussion. If contrast is not essential, perform a non-contrast protocol. This is a care/safety decision, not a protocol preference.

Traps that cost marks

Relying on the requisition instead of your own screening.
Assuming all gadolinium agents carry equal NSF risk.
Missing that a patient cannot tolerate the scan without sedation until they are on the table.
Failing to document contrast dose, agent, and any reaction.

Key points

Screen every patient, every time.
eGFR <30 + linear GBCA = stop and consult.
Treat extravasation promptly and document.

MRI Safety

Domain 3: MRI Safety

MRI safety is the highest-stakes domain. The static field, radiofrequency (RF) energy, gradients, and cryogens create hazards that are invisible. Questions test zoning, implant labelling, screening, SAR, and emergency action.

Core rules and concepts

Zones. Zone I: public area. Zone II: controlled reception. Zone III: restricted, where the 5-gauss line is monitored. Zone IV: the magnet room. Only trained staff with a documented safety screen enter Zone III/IV.
ASTM F2503 labels. MR Safe: no known hazard in any MR environment. MR Conditional: safe only under stated conditions (field strength, SAR, gradient slew rate, time after implant). MR Unsafe: never enter the magnet room.
Projectile and torque risk. Ferromagnetic objects accelerate toward the bore. Secure keys, scissors, oxygen cylinders, and infusion pumps. Use MR-safe monitoring.
RF heating and SAR. Leads, cables, and skin-to-skin loops can cause burns. Keep cables straight, separate from skin, and use padding. SAR limits depend on patient weight and mode.
Quench. A quench releases cryogenic gas. Evacuate, ventilate, and do not re-enter without oxygen monitoring and authorization.

Worked example

A patient has an MR-conditional pacemaker labelled for 1.5 T only, maximum SAR 2 W/kg, and at least 6 weeks after implantation. The order is for a 3 T cardiac MRI.

Reasoning: The conditions are not met. Field strength exceeds the label, so the device is effectively MR Unsafe for this request. Do not scan at 3 T. Contact the radiologist and device team; the exam may be moved to a 1.5 T scanner if the clinical question allows, with device programming and monitoring per protocol. Document the decision.

Traps that cost marks

Treating "MR safe" and "MR conditional" as interchangeable.
Checking the implant but not the conditions (field strength, SAR, wait time).
Allowing a ferromagnetic oxygen cylinder into Zone IV because it is "needed."
Forgetting that external leads and cables can burn even when the implant is safe.

Key points

Zone IV access is controlled, not casual.
MR Conditional means conditions, not unconditional permission.
Quench: evacuate, ventilate, do not re-enter.

MRI Physics and Instrumentation

Domain 4: MRI Physics and Instrumentation

This domain tests the physical principles that explain image contrast, signal, and artifacts: the static field (B0), RF field (B1), relaxation, gradients, k-space, and coil performance.

Core rules and concepts

Larmor frequency. The precession frequency of hydrogen is 42.58 MHz per tesla. At 1.5 T it is about 63.9 MHz; at 3 T it is about 127.7 MHz. RF coils must resonate at this frequency.
Relaxation. T1 is longitudinal recovery (fat is short/bright; fluid is long/dark). T2 is transverse decay (fluid is long/bright; fat is intermediate). T2* adds field inhomogeneity and susceptibility.
Gradients. Gradients encode position in three dimensions, enable slice selection, phase encoding, and frequency encoding, and drive diffusion and EPI. High slew rates increase nerve stimulation and acoustic noise.
K-space. The center of k-space carries contrast; the periphery carries detail. Partial Fourier, parallel imaging, and keyhole techniques exploit this.
Coils and SNR. Surface coils improve SNR near the anatomy; phased arrays combine elements. SNR rises with voxel volume, NEX, and field strength, and falls with bandwidth and parallel imaging factor.

Worked example

A 3 T scanner is installed. The technologist needs to confirm the RF frequency for proton imaging.

Reasoning: Use the Larmor equation: frequency = 42.58 MHz/T × 3 T = 127.74 MHz. At 1.5 T the same calculation gives 63.87 MHz. This matters because the transmit and receive electronics must be tuned to the correct frequency; an error would produce no signal or off-resonance artifacts. The question may ask for the approximate value, so 127.7 MHz is the expected answer.

Traps that cost marks

Confusing T1 and T2: fat is bright on T1, fluid is bright on T2.
Assuming higher field strength always means better images; susceptibility and SAR increase at 3 T.
Thinking parallel imaging improves SNR; it reduces scan time at an SNR cost.
Forgetting that T2* is affected by shimming and metal.

Key points

Larmor: 42.58 MHz/T.
T1 = recovery; T2 = decay; T2* includes inhomogeneity.
K-space center = contrast; periphery = detail.
Parallel imaging: faster, lower SNR.

Anatomy, Physiology, and Pathology

Domain 5: Anatomy, Physiology, and Pathology

This domain tests whether you can recognize normal cross-sectional anatomy in axial, coronal, sagittal, and oblique planes, and relate common pathology to MRI signal and protocol choice.

Core rules and concepts

Orientation. Know standard planes and landmarks: AC-PC line, intervertebral disc levels, biliary confluence, renal hilum, rotator cuff footprints. Label right and left correctly; radiological convention places the patient's right on the viewer's left.
Signal characteristics. Most tumors are T1 hypointense and T2 hyperintense, but melanin, fat, blood products, and protein alter signal. Contrast enhancement reflects blood-brain barrier breakdown or vascularity.
Common pathologies. Stroke (restricted diffusion), multiple sclerosis (periventricular T2/FLAIR plaques), disc herniation, ACL tear, meniscal tear, hepatic hemangioma (peripheral nodular enhancement), renal cell carcinoma, and bone marrow edema.
Physiology. CSF pulsation, cardiac motion, and respiration cause artifacts; flow voids in vessels are normal on spin-echo unless pathology alters flow.
Clinical correlation. The protocol should match the clinical question; a knee protocol is not a substitute for a hip protocol.

Worked example

A patient presents with sudden left-sided weakness. Diffusion-weighted imaging shows a bright lesion in the right MCA territory with low ADC.

Reasoning: Bright DWI with low ADC indicates restricted diffusion, typical of acute cytotoxic edema in ischemic stroke. The finding is not T2 shine-through, which would be bright on both DWI and ADC. This helps the radiologist determine acuity. The technologist's role is to ensure diffusion sequences are included and of diagnostic quality, not to diagnose.

Traps that cost marks

Reversing left and right on images.
Calling a normal flow void a vascular lesion.
Confusing T2 shine-through with true restricted diffusion.
Choosing a protocol that does not cover the clinical question.

Key points

Know normal anatomy in all three planes.
DWI bright + ADC dark = restricted diffusion.
Contrast enhancement patterns narrow the differential.
Protocol must match the clinical indication.

Image Acquisition, Protocols, and Optimization

Domain 6: Image Acquisition, Protocols, and Optimization

This domain tests protocol selection, parameter trade-offs, and image optimization for each body region. You must balance signal-to-noise ratio (SNR), contrast, resolution, scan time, and artifacts.

Core rules and concepts

Parameter trade-offs. Increasing TR lengthens T2 weighting and scan time. Increasing TE lengthens T2 weighting but reduces SNR. Increasing matrix improves resolution but lowers SNR and increases time. Increasing NEX improves SNR but increases time by the same factor.
Fast sequences. Fast spin echo (FSE) uses multiple echoes per TR; the echo train length (ETL) shortens scan time. Gradient echo is fast but sensitive to susceptibility. EPI is ultrafast but prone to distortion.
Fat suppression. Chemical fat saturation, STIR, and Dixon techniques differ; STIR is robust but suppresses all short-T1 tissues. Use post-contrast T1 fat-suppressed sequences to detect enhancement.
Parallel imaging. Acceleration factors reduce phase-encoding lines and scan time, with an SNR penalty roughly proportional to the square root of the factor.
Artifacts. Motion, aliasing, chemical shift, susceptibility, and zipper artifacts require specific fixes, not just "re-scan."

Worked example

A 2D FSE sequence has TR 4000 ms, 256 phase-encoding steps, NEX 2, and ETL 16. The scan takes 128 seconds. The patient is moving; the radiologist needs the same contrast in half the time.

Reasoning: Scan time = TR × NEX × (phase steps / ETL). 4 s × 2 × (256/16) = 128 s. Doubling ETL to 32 gives 4 × 2 × 8 = 64 s. The trade-off is slight blurring and reduced SNR, but the contrast remains T2-weighted. Alternatively, increase the parallel imaging factor, which also cuts time but lowers SNR. Choose based on the clinical priority and available coil.

Traps that cost marks

Changing several parameters at once and not knowing which caused the effect.
Forgetting that ETL and parallel imaging both reduce scan time but affect SNR differently.
Using STIR when you need to preserve fat signal.
Not documenting protocol changes.

Key points

Scan time = TR × NEX × phase steps / ETL.
Higher matrix = better resolution, lower SNR.
Parallel imaging trades SNR for speed.
Match sequence to clinical question.

Quality Management and Quality Control

Domain 7: Quality Management and Quality Control

This domain tests quality assurance, equipment performance, and continuous improvement. You must know what to test, how often, and what to do when a result fails.

Core rules and concepts

Daily QC. Check geometric accuracy, high-contrast resolution, slice thickness, slice position, uniformity, ghosting, and SNR using a phantom. Document results before clinical use.
Coil checks. Assess each coil element for signal drop, noise, or physical damage. A failed element can cause shading or signal loss.
Acceptance limits. Use facility or manufacturer tolerances; a common rule is ±2 mm geometric accuracy and ±20% uniformity, but know your local policy.
Cryogen and system checks. Monitor helium level, compressor status, and chiller performance. Low cryogen increases quench risk.
Incident and audit. Report QC failures, artifacts, and near misses. Review protocols and repeat rates; use audit data to improve.

Worked example

Daily QC shows a 20% signal drop in the right side of the uniformity phantom, and the same shading appears on patient images. The left-side values are normal.

Reasoning: The pattern suggests a coil problem, not a phantom problem. Check the coil connections and run a coil test; if an element is dead, remove the coil from clinical use and swap it. Do not pass QC by adjusting the phantom or repeating until the number looks better. Document the failure, the action, and the return-to-service verification.

Traps that cost marks

Documenting QC after scanning rather than before.
Passing a failed phantom because "it's probably the phantom."
Ignoring a single bad coil element.
Not knowing the acceptance limits for your facility.

Key points

QC is documented before clinical use.
Shading on phantom and patient = suspect coil.
Failed QC means remove from service, not "re-test until pass."
Audit and incident reporting drive improvement.