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Quizzes > Health & Medicine > Human Anatomy & Medicine

MRI Quiz: Test Your Magnetic Resonance Imaging Knowledge!

Ready for MRI practice questions and in-depth Q&A? Get started!

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustrating MRI quiz with practice questions and QA on a teal background

This MRI quiz helps you practice magnetic resonance imaging skills - anatomy, physics, safety, and common artifacts - so you can spot weak areas fast. Warm up with the anatomy review or try a quick radiology practice set , then work through the main questions to get instant answers and check gaps before an exam.

What physical principle forms the basis of magnetic resonance imaging?
Nuclear magnetic resonance
Ultraviolet absorption
Positron emission
X-ray attenuation
Magnetic resonance imaging is based on nuclear magnetic resonance. Atomic nuclei with non-zero spin align in an external magnetic field and can be excited by RF pulses. The relaxation of these spins emits a measurable signal used to create images.
Compared to CT scans, what is MRI's primary advantage?
Use of ionizing radiation
Superior soft tissue contrast
Faster scan times
Lower cost
MRI provides high soft tissue contrast without using ionizing radiation, making it ideal for imaging brain, muscle, and ligaments. CT is faster and better for bone imaging but uses X-rays. MRI scans take longer but offer superior tissue differentiation.
Which unit is used to measure the main magnetic field strength in MRI?
Hertz
Newton
Tesla
Gauss
The main magnetic field in MRI is measured in Teslas. Historically, Gauss is also used (1 T = 10 000 G). Modern clinical MRI scanners typically operate at 1.5 T or 3 T.
In a T1-weighted MRI image, which tissue typically appears brightest?
Cerebrospinal fluid
Muscle
Fat
Air
Fat has a short T1 relaxation time, causing it to recover longitudinal magnetization quickly and appear hyperintense on T1-weighted images. CSF has a long T1 and appears dark. This contrast helps differentiate tissues.
What is the primary function of gradient coils in an MRI scanner?
Transmit RF pulses
Generate the main magnetic field
Spatial encoding of the MR signal
Cool the superconducting magnet
Gradient coils produce linearly varying magnetic fields superimposed on the main field, enabling spatial localization via frequency and phase encoding. They are essential for slice selection and image formation.
Which component of an MRI system is responsible for transmitting and receiving the RF signal?
Shim coils
Gradient coils
Cooling system
RF coils
RF coils generate the oscillating magnetic field (B1) to excite protons and detect the signal during relaxation. Different coil designs maximize signal-to-noise ratio for various body parts.
What safety concern is most critical regarding ferromagnetic objects in the MRI suite?
Radiofrequency heating
Peripheral nerve stimulation
Projectile effect
Acoustic noise
Ferromagnetic objects can be accelerated into the magnet bore by the strong static field, posing a risk of injury. This is known as the projectile effect. Strict screening protocols prevent accidents.
Which of the following is an absolute contraindication for an MRI scan?
Pregnancy in first trimester
Claustrophobia
Cochlear implant
Pacemaker
Traditional pacemakers can malfunction or heat during an MRI, making them an absolute contraindication. MRI-conditional pacemakers require special protocols. Claustrophobia is a relative contraindication managed with sedation.
What formula describes the relationship between precessional frequency and magnetic field strength in MRI?
Larmor equation
Ohm's law
Fourier transform
E=mc^2
The Larmor equation ?=?B? relates the angular precession frequency (?) of nuclear spins to the magnetic field strength (B?) and the gyromagnetic ratio (?). It underpins RF excitation tuning.
How does MRI scan time typically compare to CT scan time?
MRI is slower
MRI is faster
They are equal
Depends on contrast use
MRI sequences require multiple excitations and spatial encoding steps, resulting in scan times of 20 - 60 minutes. CT uses rapid X-ray rotation and reconstructions, often completing in minutes. Extended MRI time allows detailed tissue contrast.
What type of contrast agent is gadolinium in MRI?
Ferromagnetic
Diamagnetic
Superparamagnetic
Paramagnetic
Gadolinium-based agents are paramagnetic, with unpaired electrons shortening T1 relaxation times. This increases signal intensity on T1-weighted images. Safety considerations include nephrogenic systemic fibrosis in renal impairment.
What does the term "B1 field" refer to in MRI?
Shim field
Radiofrequency excitation field
Frequency encoding gradient
Main magnetic field
The B1 field is the oscillating magnetic field produced by RF coils, tipping the net magnetization into the transverse plane. It is perpendicular to the main B0 field. Uniform B1 improves image quality.
In MRI, what is the flip angle?
The angle between gradient coils
The pulse sequence timing
The angle the net magnetization is tipped by the RF pulse
The phase encoding increment
Flip angle is the degree to which the net magnetization vector is rotated from alignment with B0 by an RF pulse. Common angles are 90° in spin echo and <90° in gradient echo sequences. It influences image contrast and signal.
Which parameter directly affects slice thickness in MRI?
Field of view
Number of phase encodings
Gradient strength during slice selection
Receiver bandwidth
Slice thickness is determined by the RF pulse bandwidth and the strength of the slice-selection gradient. Stronger gradients yield thinner slices for a given bandwidth. Slice thickness affects spatial resolution and signal.
Increasing the echo time (TE) in an MRI sequence primarily enhances which image contrast?
Diffusion weighting
T1 weighting
T2 weighting
Proton density weighting
Longer TE allows transverse magnetization to decay, highlighting T2 differences between tissues. T2-weighted images show fluids as hyperintense. Short TE sequences minimize T2 effects.
Which repetition time (TR) setting favors proton density - weighted imaging?
Short TR, short TE
Long TR, long TE
Long TR, short TE
Short TR, long TE
Proton density weighting uses a long TR to minimize T1 contrast and a short TE to minimize T2 decay. This emphasizes proton density differences. Other TR/TE combinations highlight T1 or T2 contrasts.
Which pulse sequence uses an inversion time to null the signal from fat?
Proton density
Gradient echo
T2 FLAIR
STIR
STIR (Short TI Inversion Recovery) uses an inversion pulse and a TI set to the null point of fat's longitudinal magnetization. This suppresses fat signal and enhances fluid detection. FLAIR nulls CSF, not fat.
What advantage does fast spin echo (FSE) have over conventional spin echo?
Increased T1 contrast
Elimination of susceptibility artifacts
Better chemical shift resolution
Shorter scan time
Fast spin echo collects multiple echoes per TR using repeated 180° pulses, reducing total scan time. It maintains good image quality and T2 contrast. Conventional spin echo acquires one echo per TR.
Which key difference distinguishes gradient echo from spin echo sequences?
Dependence on long TR
Use of 180° refocusing pulse
Necessity of inversion recovery
Chemical shift suppression
Spin echo uses a 180° refocusing pulse to correct for field inhomogeneities and T2* effects. Gradient echo omits the 180° pulse, making it sensitive to T2* and faster imaging. This also changes contrast and susceptibility behavior.
What is the principle behind parallel imaging techniques in MRI?
Using multiple gradient sets
Reducing RF power
Exploiting coil sensitivity profiles
Increasing field strength
Parallel imaging accelerates acquisition by undersampling k-space and using multiple coil sensitivity profiles to reconstruct missing data. Techniques like SENSE and GRAPPA are common. This reduces scan time but may lower SNR.
In MRI, what does k-space represent?
Spatial domain of the image
RF pulse waveform
Raw frequency and phase encoding data
Magnetic field gradient strength
K-space is the matrix storing raw MRI data in frequency and phase encoding dimensions. An inverse Fourier transform converts k-space data into the spatial domain image. The center contains contrast information; edges store resolution.
Which artifact arises from differences in resonance frequency between fat and water?
Gibbs ringing
Motion artifact
Aliasing artifact
Chemical shift artifact
Chemical shift artifact occurs at fat-water interfaces due to their different resonant frequencies, causing signal misregistration along the frequency-encoding direction. It appears as bright or dark bands. Adjusting bandwidth can reduce it.
Susceptibility artifacts in MRI are most prominent near which of the following?
Air-tissue interfaces
Homogeneous soft tissue
Fluid-filled structures
Uniform fat beds
Susceptibility artifacts occur at interfaces where magnetic susceptibility varies sharply, such as air-tissue or metal-tissue boundaries. This distorts the local magnetic field and causes signal loss or distortion.
What does SAR stand for in MRI safety considerations?
Specific Absorption Rate
Spatial Acquisition Rate
Signal Absorption Ratio
Signal Acquisition Rate
Specific Absorption Rate measures the RF energy deposited in the patient's body per unit mass. High SAR can cause tissue heating and requires monitoring. Regulatory limits ensure patient safety.
Which MRI technique visualizes blood vessels without contrast injection using flow-related enhancement?
Diffusion-weighted imaging
Proton density imaging
T2 FLAIR
Time-of-flight MR angiography
Time-of-flight (TOF) MR angiography exploits inflow enhancement of unsaturated blood moving into the imaging slab. Stationary tissues are saturated and appear darker. It visualizes vessels without contrast agents.
What contrast mechanism does diffusion-weighted imaging (DWI) exploit?
Magnetic susceptibility
Fat content
Blood flow velocity
Molecular water motion
DWI measures the random Brownian motion of water molecules. Areas of restricted diffusion, such as acute stroke or certain tumors, appear hyperintense. It uses strong diffusion-sensitizing gradients.
Gadolinium contrast agents primarily shorten which relaxation time?
Neither T1 nor T2
Both equally
T2 more than T1
T1 more than T2
Gadolinium accelerates T1 relaxation more effectively, increasing signal on T1-weighted images. At high concentrations, it can also shorten T2, leading to signal loss. Dosing balances these effects.
How does increasing receiver bandwidth affect SNR and chemical shift artifact?
Increases both SNR and artifact
Decreases both SNR and artifact
Decreases SNR, reduces artifact
Increases SNR, worsens artifact
A wider receiver bandwidth reduces chemical shift artifact by sampling a broader frequency range but decreases SNR since more noise is integrated. Narrow bandwidth improves SNR but worsens shift.
Which encoding direction is responsible for slice selection artifacts when mis-set?
Phase encoding
Readout direction
Slice selection encoding
Frequency encoding
Slice selection artifacts arise when the slice?selection gradient or RF bandwidth is misaligned, causing imperfect slice profiles. Accurate gradient calibration and bandwidth settings ensure correct slice thickness and location.
What artifact occurs when anatomy outside the field of view is aliased into the image?
Chemical shift artifact
Susceptibility artifact
Gibbs ringing
Aliasing (wrap-around)
Aliasing or wrap-around happens when the field of view is too small and anatomy outside it is mapped back into the image due to under-sampling in phase-encoding direction. Increasing FOV or using anti-aliasing filters corrects this.
What process is used to correct B0 inhomogeneity in an MRI scanner?
Inversion recovery
Gradient echo
Shimming
Spin echo
Shimming adjusts small corrective magnetic fields using shim coils (passive or active) to homogenize the main field B0. Proper shimming improves image uniformity and reduces artifacts.
Which rapid imaging technique acquires an entire image after a single excitation?
Fast spin echo
Balanced steady-state free precession
Inversion recovery
Echo-planar imaging (EPI)
Echo-planar imaging captures all k-space lines after a single RF excitation by rapidly switching gradients. This enables millisecond-scale imaging used in fMRI and DWI. It is sensitive to distortion and susceptibility.
What is the principle of fat-saturated (FatSAT) sequences?
Inversion recovery with TI nulling water
Frequency-selective RF pulse to suppress fat
Using short TE
Gradient reversal
FatSAT uses a frequency-selective RF pulse to excite and dephase fat protons before the imaging sequence, suppressing their signal. This enhances contrast between fat and other tissues. It requires uniform B0 and B1 fields.
Which MRI technique separates water and fat images using two different echo times?
STIR
Dixon method
SSFP
EPI
The Dixon technique acquires two images at different echo times where fat and water signals are in-phase and out-of-phase. Mathematical recombination yields separate water-only and fat-only images. It is robust against B1 inhomogeneity.
Which method labels arterial blood water as an endogenous tracer for perfusion imaging?
Time-of-flight MRA
Diffusion tensor imaging
Dynamic contrast - enhanced MRI
Arterial spin labeling (ASL)
ASL uses magnetically labeled arterial blood water as an endogenous tracer to quantify tissue perfusion without exogenous contrast. It acquires labeled and control images and calculates cerebral blood flow.
The BOLD signal in fMRI is based on which physiological effect?
Susceptibility changes from oxy/deoxyhemoglobin
Diffusion of water molecules
T1 shortening by contrast
Fat suppression
BOLD fMRI detects changes in magnetic susceptibility due to varying levels of oxyhemoglobin and deoxyhemoglobin during neuronal activation. Deoxyhemoglobin is paramagnetic, altering T2* signal. This contrast localizes brain activity.
Chemical Exchange Saturation Transfer (CEST) MRI primarily detects what?
Blood flow
Metabolite exchange between molecules and water
Diffusion anisotropy
Fat fraction
CEST MRI applies a frequency-selective saturation pulse to exchangeable protons in metabolites, which transfer saturation to water, reducing its signal. It enables molecular and pH imaging.
Which modality provides spectra of chemical compounds in tissues?
Phase-contrast MRI
Diffusion-weighted imaging
Echo planar imaging
MR spectroscopy
Magnetic Resonance Spectroscopy measures resonance frequencies of various metabolites, providing chemical composition of tissues. It identifies compounds like NAA, choline, and creatine in the brain. Useful in oncology and neurology.
Quantitative T1 mapping in MRI is used to:
Measure actual T1 relaxation times in ms
Visualize blood vessels
Suppress fat signal
Acquire rapid EPI images
T1 mapping quantifies tissue-specific T1 relaxation times, enabling objective assessment of tissue characteristics and pathology. It uses multiple inversion times or variable flip angles. Values aid in disease characterization.
What is a key benefit of using a 7 Tesla MRI system compared to 3 Tesla?
Lower specific absorption rate
Shorter scan times automatically
Improved signal-to-noise and spatial resolution
Reduced susceptibility artifacts
7 T MRI provides higher signal-to-noise ratio and spatial resolution, enabling finer anatomical detail and functional studies. However, it increases susceptibility artifacts and SAR. It is mainly used in research.
Diffusion tensor imaging (DTI) primarily assesses:
Magnetic susceptibility
Fat fraction
Perfusion
Anisotropic diffusion of water in tissues
DTI measures the directional dependence of water diffusion, revealing white matter tracts in the brain. It computes metrics like fractional anisotropy. Useful in neurology and connectivity studies.
How do T1 and T2 relaxation times change at ultra-high fields (?7 T)?
Both remain unchanged
T1 decreases, T2 increases
T1 increases, T2 decreases
Both decrease
At ultra-high fields, T1 relaxation times lengthen due to increased energy gaps, while T2 and T2* shorten because of higher susceptibility and faster dephasing. This affects sequence optimization.
What is the principle behind compressed sensing MRI?
Acquiring full k-space with stronger gradients
Random undersampling and nonlinear reconstruction
Increasing TR and TE
Using multiple RF channels
Compressed sensing reconstructs images from randomly undersampled k-space by exploiting image sparsity and nonlinear iterative algorithms. It allows significant acceleration while preserving image quality.
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Study Outcomes

  1. Understand MRI Fundamentals -

    Grasp core principles of magnetic resonance imaging physics, instrumentation, and safety considerations.

  2. Identify Pulse Sequence Characteristics -

    Recognize and differentiate key MRI pulse sequences, including T1-, T2-, and PD-weighted imaging.

  3. Analyze Image Artifacts -

    Detect common MRI artifacts and explain their causes and strategies for mitigation.

  4. Apply Protocol Selection Skills -

    Choose appropriate imaging parameters and protocols for various clinical scenarios.

  5. Interpret MRI Questions and Answers -

    Use in-depth MRI questions and answers to deepen your understanding of diagnostic criteria and imaging principles.

  6. Evaluate Your Quiz Performance -

    Leverage MRI practice questions feedback to assess your strengths, identify areas for improvement, and build confidence.

Cheat Sheet

  1. T1 vs. T2 Relaxation Times -

    Understanding T1 (longitudinal) and T2 (transverse) relaxation is crucial for MRI quiz success: T1 values (e.g., fat ~250 ms, water ~4000 ms) govern recovery along B0, while T2 values (fat ~70 ms, water ~2000 ms) dictate signal decay. Use the mnemonic "T1 is till 1" (recovery) and "T2 is to 2" (decay) to remember which process each describes. The signal equation S∝(1 - e - TR/T1)·e - TE/T2 (Hoult & Beam, Prog. NMR Spectrosc., 1976) ties relaxation to TR/TE settings.

  2. Key Pulse Sequences: Spin Echo vs. Gradient Echo -

    Spin echo (SE) uses a 90° - 180° pulse pair for refocusing, minimizing susceptibility artifacts, while gradient echo (GRE) omits the 180° pulse for faster scans but increased inhomogeneity sensitivity (Smith et al., Radiology, 2010). Remember SE for "Solid, Straightforward" contrast and GRE for "Greatly Rapid Exploration." Compare TR/TE values: SE (longer TR/TE) vs. GRE (short TR/TE) to predict T1-/T2*-weighting.

  3. Common Image Artifacts -

    Artifacts like aliasing (wrap-around), chemical shift (fat/water misregistration ~3.5 ppm), and susceptibility (metal-related distortion) often appear in MRI practice questions. Correct aliasing by increasing FOV or using saturation bands, and reduce chemical shift by widening bandwidth (Med. Phys., AAPM Task Group 9, 1984). Spotting these in your MRI quiz prep will boost both accuracy and confidence.

  4. Contrast Agents and Relaxivity -

    Gadolinium-based agents shorten T1 by increasing relaxivity (r1), enhancing bright signal in vascular and tissue studies (ACR Manual on Contrast Media, 2022). Recall "Gd3+ gets 3× more relaxivity" as a memory trick for its tri-positive charge and strong paramagnetic effect. Always consider dose limits (0.1 mmol/kg) and NSF risk in renal impairment.

  5. Safety & SAR Limits -

    Specific absorption rate (SAR) measures RF energy deposition (W/kg) with FDA head/body limits of 3.2/4.0 W/kg averaged over 10 minutes (FDA Guidance, 2019). Use the rhyme "4 to stay alive" to recall the 4 W/kg whole-body cap and adjust TR, flip angle, or sequence type to manage patient heating during MRI practice questions and real scans. Proper SAR control ensures safe learning and clinical scanning.

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