Datasets:

HPAI-BSC
/

MRI-MCQA

id stringlengths 6 14	question stringlengths 27 341	golden_answers sequencelengths 1 1	choices sequencelengths 4 4	metadata dict
q_CARDIAC1_00	Which cardiac chambers are typically imaged on the short-axis view?	[ 3 ]	[ "RA and RV", "RA and LA", "LA and LV", "RV and LV" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The short axis view is typically used to show the left and right ventricles." }
q_CARDIAC1_01	What structure is optimally displayed on the so-called “candy-cane” view?	[ 0 ]	[ "Thoracic aorta", "Circumflex artery", "Left main coronary artery", "Right coronary artery" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "The candy-cane view is an oblique sagittal section that lays out the ascending, transverse, and descending thoracic aorta and its proximal branches." }
q_CARDIAC1_02	Why might one wish to start two IV’s prior to MRI if stress testing is being performed?	[ 2 ]	[ "The second serves as backup in case the first IV fails.", "The total amount of fluid and medications required during the exam exceed the capacity of a single average-bore IV.", "Gadolinium contrast and adenosine cannot be given through the same line.", "The second IV is needed for blood sampling during the exam." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "Gadolinium and adenosine cannot be given through the same line, so two separate IVs are required. Separate lines are optional if regadenoson or dobutamine are used." }
q_CARDIAC1_03	Which of the following foods and medications should be discontinued at least 12-24 hours before a stress MRI?	[ 2 ]	[ "Nitroglycerin", "Calcium-channel blockers", "Caffeinated beverages", "Quinidine" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Patients should be advised not to consume stimulants such as coffee, tea, caffeinated sodas, energy drinks, and chocolate within 12-24 hours of the scan. These can interfere with the efficacy of the pharmacological stress testing and interpretation of the examination." }
q_CARDIAC1_04	What is the most common EKG change noted when a patient is placed in an MRI?	[ 2 ]	[ "Reduction of the R-wave", "Inversion of the R-wave", "Elevation of the T-wave", "ST-segment elevation" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Although all the above phenomena can occur, elevation of the T-wave is most frequently observed. This elevation may be so marked that the T-wave actually becomes larger than the QRS-complex." }
q_CARDIAC1_05	What is the cause of the EKG changes described above?	[ 0 ]	[ "Ionic currents induced by thoracic blood flow", "Susceptibility effects", "Stimulation of accessory cardiac conduction pathways", "Induced currents in the EKG leads" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "This magnetic field effect on the EKG does not originate in the heart itself, but represents a superimposed voltage within blood in the descending thoracic aorta which has been induced by its flow in the magnetic field. The induction of a voltage in a conductive fluid flowing through a magnetic field is called the magnetohydrodynamic (MHD) effect." }
q_CARDIAC1_06	Which EKG wave is primarily used for cardiac triggering?	[ 2 ]	[ "P-wave", "Q-wave", "R-wave", "T-wave" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "Cardiac gating is typically performed using detection of the R-wave since this is usually the most prominent feature of the EKG. The R-wave coincides with the beginning of ventricular systole." }
q_CARDIAC1_07	The R-wave corresponds to what cardiac event?	[ 1 ]	[ "Beginning of atrial contraction", "Beginning of ventricular systole", "Peak contraction of the ventricle", "Beginning of ventricular diastole" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "The R-wave coincides with the beginning of ventricular systole." }
q_CARDIAC1_08	If the heart rate is 100 bpm, what is the length of the R-R interval in milliseconds?	[ 2 ]	[ "60 ms", "100 ms", "600 ms", "1000 ms" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "Over 1 minute = 60 seconds, there are 100 beats marked by R waves. The R-R interval is therefore 60s /100 = 0.6 s or 600 ms." }
q_CARDIAC1_09	In the patient above with a heart rate of 100 bpm, which of the following TR values would not be available for a prospectively gated sequence?	[ 1 ]	[ "600 ms", "900 ms", "1200 ms", "1800 ms" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The repetition time (TR) in a prospectively gated sequence cannot be freely set but must be a multiple of the average R-R interval. Thus for a patient with heart rate = 100, the only choices for TR would be 600 ms, 1200 ms, 1800 ms, etc." }
q_CARDIAC1_10	Continuing the above example in the patient with HR = 100 bpm, what would be the TR if a gating factor of 4 were chosen?	[ 3 ]	[ "125 ms", "600 ms", "1200 ms", "2400 ms" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "The R-R multiple chosen is called the gating factor. So, if the average R-R interval were 600 ms, the corresponding TR value would be 600 x 4 = 2400 ms." }
q_CARDIAC1_11	In a gated study, the time between the first R-wave and the beginning of data acquisition is known as the	[ 2 ]	[ "Trigger window", "Acquisition window", "Trigger delay", "Quiescent interval" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Trigger delay is the time interval between the first R-wave and the beginning of data acquisition." }
q_CARDIAC1_12	Which of the following is not an advantage of retrospective gating compared to prospective gating?	[ 3 ]	[ "TR is not restricted to be a multiple of the R-R interval", "Data acquired during arrythmias can be rejected.", "Data acquired during patient motion can be rejected.", "Magnetohydrodynamic distortions in the EKG can be corrected." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "All are true advantages except (d)." }
q_CARDIAC1_13	For cardiac imaging navigator pulses are most commonly placed	[ 0 ]	[ "On the dome of the right hemidiaphragm", "On the dome of the left hemidiaphragm", "On the left ventricle", "On the chest wall" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Navigator pulses are typically applied so as to excite 1-dimensional beams or 2-dimensional planes of tissue. Although navigators may be placed over the heart directly, more commonly they are placed to intersect the right hemidiaphragm at its dome." }
q_CARDIAC1_14	Which one of the following statements about double IR sequences for cardiac imaging is true?	[ 1 ]	[ "The first 180°-pulse is spatially selective, while the second 180°-pulse is non-selective.", "Blood suppression requires outside blood flowing in and displacing blood initially within the slice.", "Both blood and fat signals are suppressed.", "Short TI values are required when the heart rate is slow." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The first inverting pulse is spatially non-selective, while the second pulse is spatially selective, so (a) is false. Inflow of outside blood is a critical requirement for DIR to function properly, so (b) is true. DIR does not suppress fat, so (c) is false. Finally, long (not short) TI values are required when the heart rate is slow." }
q_CARDIAC1_15	An advantage of triple IR over double IR for cardiac imaging is	[ 0 ]	[ "Suppression of pericardial and mediastinal fat", "Shorter imaging times", "More freedom on choice of TI values", "Improved T1 contrast" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Suppression of fat using a third inverting pulse is the primary advantage for triple IR. It comes with limitations, including longer imaging times, less choice on TI values, and replacement of T1 contrast by T2 contrast." }
q_CARDIAC1_16	How many distinct segments are enumerated in the American Heart Association (AHA) standard model for left ventricular anatomy that are displayed on polar/target/bull’s eye plots?	[ 1 ]	[ "15", "17", "19", "21" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "There are 6 basal, 6 middle and 5 apical segments adding to a total of 17." }
q_MRA-I_00	Which of the following methods is considered a “dark blood” MRA technique?	[ 3 ]	[ "Time-of-flight MRA", "Gadolinium-enhanced MRA", "SSFP MRA", "Susceptibility-weighted MRA" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Dark (\"black\") blood MRA techniques suppress signal from flowing blood while maintaining high signal in the surrounding stationary tissues, thus rendering the vessels black. Of those listed, only susceptibility-weighted MRA is a black blood technique." }
q_MRA-I_01	Which of the following methods is not a “bright blood” MRA technique?	[ 1 ]	[ "Phase-contrast MRA", "Double inversion recovery MRA", "Arterial spin-labeled MRA", "Ferumoxytol-enhanced MRA" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Single, double, or even triple 180°-inversion pulses may be used to suppress the signal from blood and other tissues (such as fat or myocardium) based on their respective T1 values. Black blood IR methods are most commonly used for cardiac and vessel wall imaging." }
q_MRA-I_02	Which of the following is not an advantage of dark-blood compared to bright-blood MRA techniques?	[ 2 ]	[ "Less overestimation of stenosis", "Better delineation of vessel walls", "Better sensitivity to low-flow states", "Fewer pulsation artifacts" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Dark-blood MRA has some unique advantages compared to bright-blood techniques. Flow separation and turbulence, which cause unwanted signal losses and overestimation of stenoses on bright-blood MRA, paradoxically improve image quality on dark-blood MRA. Because intraluminal signal is suppressed, vessels containing \"black blood\" do not generate pulsation (ghosting) artifacts. Additionally, the lack of intraluminal signal allows the walls of vessels (or cardiac chambers) to be clearly delineated. For these reasons, dark-blood techniques are predominantly used in cardiac imaging and for evaluation of diseases of the vessel wall (atherosclerotic plaque and dissection). Although an excellent method for imaging high-flow vessels, dark-blood techniques are less sensitive to slower flow states. \"Black\" blood is difficult to separate from adjacent low-signal non-vascular structures, such as calcifications, cortical bone, and air." }
q_MRA-I_03	What is the purpose of the so-called “traveling sat” pulses in 2D-TOF MRA?	[ 0 ]	[ "To reduce venous contamination", "To maximize contrast between stationary tissues and blood", "To minimize signal losses from phase dispersion", "To increase signal from inflowing spins" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "These sat pulses are used to suppress venous signal that would normally flow into each slice." }
q_MRA-I_04	What is the purpose of using moderate-to-large flip angles (30°−60°) in 2D-TOF-MRA sequences?	[ 1 ]	[ "To reduce venous contamination", "To maximize contrast between stationary tissues and blood", "To minimize signal losses from phase dispersion", "To increase signal from inflowing spins" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Larger flip angles produce more magnetic saturation of stationary tissues within the imaged volume, and thus maximize contrast with inflowing blood." }
q_MRA-I_05	Concerning optimal parameter selection for TOF MRA sequences, which of the following statements is true?	[ 2 ]	[ "TR should be very long to insure the greatest degree of inflow enhancement.", "TE should be very long to increase vascular signal from T2 effects.", "Slice orientation should be perpendicular to the direction of flow.", "Flip angle (α) should be very small to increase tissue saturation." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Only (c) is true. The benefits of very long TR to improve inflow enhancement is offset by increased signal from background tissue. TE should be short to reduce spin-phase losses. Flip angles should be moderate to large to decrease tissue from static tissues." }
q_MRA-I_06	Blood in an artery with mean velocity of 50 cm/s flows perpendicularly into a 2-cm-thick slice. At what value of TR is flow-related enhancement maximized?	[ 3 ]	[ "10 ms", "20 ms", "30 ms", "40 ms" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "Maximum flow-related enhancement occurs when inflowing blood completely replaces that present in a given slice. When flow is perpendicular to the slice, maximum enhancement occurs when V ≥ d / TR, or equivalently, when TR ≥ d /V. For d = 2 cm and V = 50 cm/s, this means a TR ≥ 2/50 s = 0.04 s = 40 ms" }
q_MRA-I_07	Concerning magnetization-transfer enhanced MRA, which statement is false?	[ 0 ]	[ "It is effective for both time-of-flight and phase-contrast MRA", "It is effective for both non-contrast and contrast-enhanced MRA", "Small vessel detail is improved", "Image acquisition time is slightly prolonged." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "MT-MRA is used only for TOF and contrast-enhanced MRA. It offers no benefit for PC-MRA." }
q_MRA-I_08	Concerning variable (ramped) pulses, which statement is true?	[ 2 ]	[ "They are useful in both 2D and 3D TOF MRA.", "Their flip angles are designed to decrease linearly along the direction of flow.", "They are designed to produce greater saturation of stationary tissues deep in the slab.", "They are designed to increase the absolute signal of flowing blood deep in the slab." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Variable (ramped) RF pulses address the progressive loss of MRA signal from vessels extending deep into a 3D-TOF slab. (They are not used for 2D TOF). The flip angle is designed to increase along the direction of flow, producing greater saturation of stationary tissues deep in the slab. (Answer c is correct). They also suppress blood slightly, but not as much as stationary tissues." }
q_MRA-I_09	A common artifact seen with MOTSA MRA is called	[ 0 ]	[ "The venetian blind artifact", "The stair-step artifact", "The velocity aliasing artifact", "The ringing (Maki) artifact" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "Because each MOTSA slab is acquired at separate times, exact registration of position and signal intensity of adjacent slabs may not be possible. This gives rise to the so-called venetian blind artifacts characteristic of this technique." }
q_MRA-I_10	A common artifact seen with 2D-TOF MRA is called	[ 1 ]	[ "The venetian blind artifact", "The stair-step artifact", "The velocity aliasing artifact", "The ringing (Maki) artifact" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The stair-step artifact is common on 2D-TOF MRA because patient motion between slices." }
q_MRA-I_11	In subclavian steal syndrome, the blood flow in one of the two vertebral arteries becomes reversed. What will be the appearance of this reversed flow vertebral artery on a 2D-TOF MRA of the neck?	[ 3 ]	[ "Its appearance will be identical to the contralateral (normally flowing) vertebral artery.", "It will appear paradoxically brighter than contralateral vertebral artery.", "It will appear slightly less bright than the contralateral vertebral artery.", "It will be non-visualized, suggesting an occlusion." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "2D-TOF sequences utilize traveling saturation pulses upstream from the imaged slice to eliminate venous contamination. In the neck, these pulses effectively eliminate signal in the jugular and other deep veins, but will also eliminate signals from arterial flows whose directions have been reversed. So (d) is the correct answer." }
q_MRA-I_12	Why might a phase-contrast (PC) MRA of the head be preferred over a TOF MRA in a patient with cerebral hemorrhage?	[ 2 ]	[ "The spatial resolution of PC MRA is much higher.", "PC MRA has been shown to be more accurate in the detection of aneurysms.", "T1-shine through of a hematoma does not affect PC MRA but may obscure TOF MRA.", "The acquisition time of PC MRA is much shorter than equivalent TOF techniques." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "TOF MR angiographic images are displayed using a maximum intensity projection (MIP) algorithm. In addition to bright blood vessels, any other material with high signal intensity will \"shine through\" and \"contaminate\" the MIP image. Since underlying TOF MRA pulse sequences are T1-weighted, short T1 materials (hematoma, gadolinium, and fat) are primarily responsible for this phenomenon. PC MRA, however, relies on phase shift differences due to motion, and does not suffer from shine-though." }
q_MRA-I_13	The underlying mechanism of phase-contrast MRA is based on	[ 0 ]	[ "Bipolar flow-encoding gradients", "Unipolar flow-encoding gradients", "RF-phase cycling between excitations", "Use of a linear gradient with constant slope along the phase-encoding axis" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "PC MRA utilizes bipolar gradients, applied along one or more directions along which flow information is desired. A stationary spin subjected to such a gradient pair will experience no net phase shift, but a moving spin will have a net phase shift proportional to its velocity." }
q_MRA-I_14	The units of the VENC (velocity-encoding) parameter for PC MRA are	[ 1 ]	[ "dimensionless", "cm/s", "cm²/s", "cm/s²" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "VENC is a velocity, so the correct answer is (b), cm/s." }
q_MRA-I_15	If the VENC in a PC MRA is set at 60 cm/s, the strength and duration of the bipolar gradients are adjusted so that blood flowing at 60 cm/s has a phase shift of	[ 2 ]	[ "+60º", "+90º", "+180º", "+360º" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "For a given VENC, the bipolar gradients are adjusted so blood velocities at this level are assigned a +180º phase shift." }
q_MRA-I_16	If the VENC is set to 50 cm/s, and the actual forward flow blood velocity is 75 cm/s, what velocity will be displayed on the PC MRA?	[ 3 ]	[ "+50 cm/s", "+75 cm/s", "+25 cm/s", "−25 cm/s" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "If the chosen value of VENC is 50 cm/sec, the bipolar gradient is adjusted so that flows of +25 and +50 cm/sec are assigned a phases of +90° and +180° respectively. If the actual velocity is +75 cm/sec, this flow will be mapped to +270°, a value that cannot be distinguished from a phase shift of −90°. Instead of representing the +75-cm/sec flow as its actual velocity, the computer will assign it a flow of 25 cm/sec in the opposite direction!" }
q_MRA-I_17	A PC MRA using bipolar gradients whose VENCs are properly set determines that velocities in the three cardinal directions are vx = −52 cm/s, vy = +24 cm/s, and vz = +72 cm/s. When displayed as a magnitude (speed) image, the brightness of each voxel is proportional to	[ 1 ]	[ "148 cm/s", "92 cm/s", "72 cm/s", "44 cm/s" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 4, "hint": "By definition, speed = √{v²x + v²y + v²z} = √{(−52)² + (+24)² + (+72)²} = √{8464} = 92 cm/s." }
q_MRA-I_18	Concerning the accuracy of PC-MRA velocity measurements compared to Doppler in medium to large vessels, the two measurements generally lie within what percentage of each other?	[ 1 ]	[ "Less than 1%", "About 5%", "15% - 25%", "More than 25%" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The two measurements are generally within about 5% of each other." }
q_MRA-I_19	Which of the following situations would velocity measurements by PC MRA be the most accurate?	[ 0 ]	[ "Imaging plane perpendicular to the direction of flow", "Pixel size close to the vessel diameter", "Turbulent flow", "Sampling of great vessel flows using 8 frames per cardiac cycle." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Measurement of flow velocities is most accurate when the vessel is perpendicular to the plane of imaging. When the pixel size exceeds one-third of the vessel diameter, significant partial volume effects may occur with underestimation of flow and peak velocities. When velocities change suddenly in magnitude, direction, or both, as they do in turbulence, accuracy of flow measurements declines. If the data sampling rate throughout the cardiac cycle is too low, flow may not be measured at its peak value. For imaging the great vessels at least 16 frames per cardiac cycle should be sampled" }
q_MRAIIQUIZ_00	Which statement about Gated 3D-FSE MRA techniques is incorrect?	[ 2 ]	[ "They can be gated either to the EKG or peripheral pulse.", "Co-registered images are obtained in diastole and systole.", "Diastolic and systolic images are added together to produce the angiogram.", "Image contrast is based on the long T2 of blood." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "The sequence is cardiac gated either to the EKG or peripheral pulse. Co-registered images are obtained in diastole and systole. During diastole, the signal in both arteries and veins is high reflecting the long T2 of blood. During systole, venous signal remains high but arterial signal drops due to flow-related signal loss. Subtraction (not addition) of the systolic from the diastolic images results in a pure arterial image." }
q_MRAIIQUIZ_01	Which of the following is not a disadvantage of 3D-FSE MRA?	[ 0 ]	[ "Required use of gadolinium contrast.", "Overestimation of stenoses", "Vascular pulsation artifacts", "Sensitivity to cardiac arrythmias" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Option (a) is false. The main advantage of 3D-FSE MRA is that it does not require contrast, a property that may be important in patients with renal insufficiency (where receiving gadolinium might place them at risk for nerphogenic systemic fibrosis)." }
q_MRAIIQUIZ_02	Intravascular contrast in balanced steady-state free precssion (b-SSFP) MRA is primarily related to which property of blood?	[ 3 ]	[ "High spin-density", "Long T1", "Long T2", "High T2/T1 ratio" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "b-SSFP MRA exploits the differences between the relatively high T2/T1 ratio of blood compared to most other tissues." }
q_MRAIIQUIZ_03	What is the main reason b-SSFP MRA sequences are not routinely used in intracranial imaging?	[ 1 ]	[ "Its spatial resolution is insufficient to resolve the major intracranial vessels.", "The signal from intracranial vessels is obscured by high signal from nearby CSF.", "Intracranial vessels typically demonstrate turbulent flow which disrupts the SSFP.", "Susceptibility artifacts from the skull base produce troublesome zebra-stripe artifacts over most of the brain." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Like blood, CSF has a high T2/T1 ratio and so will appear bright on SSFP MRA sequences. Since the arteries at the base of the brain are literally “bathed” in CSF, this is the main reason the sequences are not commonly used intracranially." }
q_MRAIIQUIZ_04	The purposes of the inversion pulse(s) used in inflow-enhanced, IR-prepped 3D-SSFP MRA include all of the following except	[ 3 ]	[ "Nulling of signal from water-containing background tissue.", "Nulling of signal from fat", "Nulling of signal from venous blood", "Hyperpolarization of incoming arterial spins." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The inversion pulses allow arterial inflow to be relatively accentuated due to background and venous suppression, not because of hyperpolarization." }
q_MRAIIQUIZ_06	Which of the following statements about the Quiescent-Interval Single-Shot (QISS) MRA is incorrect?	[ 0 ]	[ "It does not require cardiac gating.", "It does not utilize gadolinium contrast.", "It is primarily used for extremity MRA", "Unsaturated blood enters the imaged slice during the quiescent interval (QI)" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "QISS is a cardiac-gated, non-contrast inflow technique bearing some similarities to 2D time-of-flight (TOF) and inflow-enhanced SSFP MRA. It is especially designed for peripheral MRA. Fresh (fully magnetized/unsaturated) enters the slice during the quiescent interval, with arterial signal generated by a balanced-SSFP sequence." }
q_MRAIIQUIZ_07	Which of the following statements about contrast-enhanced (CE)-MRA is false?	[ 2 ]	[ "If scanning is performed too early after injection, inadequate vascular visualization may result.", "Scanning performed too late after injection may result in venous contamination.", "If you incorrectly time the bolus on the first acquisition, you can wait 10 minutes and repeat the injection.", "Signal generation is typically performed using a 3D T1-weighted spoiled gradient echo sequence with short TR and TE." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "Ideally, CE-MRA should be performed when the contrast agent arrives in the vessel at or near its peak concentration. To early and you don’t see the vessel; too late and you may get venous contamination. You only get one chance to get it right and cannot repeat the sequence until the next day or two when the gadolinium clears out of the system." }
q_MRAIIQUIZ_08	What is fluoroscopic triggering for MRA?	[ 3 ]	[ "A method that uses information from an x-ray fluoroscope to assist in timing of the gadolinium bolus.", "A method to estimate timing of arrival of a small (1-2 ml) test bolus of gadolinium.", "A 3D-phase contrast method to estimate the distribution of contrast throughout the entire imaging volume.", "A method providing a “fluoroscopic-like” MR image during transit of a full contrast bolus at which time the MRA acquisition can begin." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "In fluoroscopic triggering the full bolus of contrast (~20 mL) is administered while a fluoroscopic-like picture of the artery of interest is acquired using a rapid 2D gradient-echo technique. The technologist can then initiate MRA acquisition or the triggering can be done automatically." }
q_MRAIIQUIZ_09	The preferred k-space sampling method used for most 3D-CE-MRA sequences is called	[ 0 ]	[ "Elliptical-centric ordering", "Linear ordering", "Sequential ordering", "Stochastic ordering" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Elliptical-centric ordering is now the preferred k-space sampling method used for most CE-MRA examinations. Linear methods may still be used on older equipment and for MRA of the distal extremities where arrival of the contrast bolus may be prolonged or its exact timing difficult to predict." }
q_MRAIIQUIZ_10	What type of k-space sampling is used in modern time-resolved MRA sequences like TRICKS and TWIST?	[ 2 ]	[ "Zig-zag", "Cartesian", "Radial", "Spiral" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Modern time-resolved MRA techniques typically use radial sampling schemes, acquiring 3D k-space in segmented round or oval \"cylinders\"." }
q_MRAIIQUIZ_11	Which technical component is not a feature used in modern time-resolved MRA sequences like TRICKS and TWIST?	[ 0 ]	[ "3D-SSFP acquisition", "Both phase- and read-conjugate symmetry", "Elliptical-centric ordering", "Parallel imaging" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Option (a) is incorrect. Time-resolved MRA methods have at their core a 3D-spoiled GRE sequence with thin slices, very short TRs and TEs, low flip angles, use of both read- and phase-conjugate symmetry, parallel imaging acquisition, and zero-interpolation filling in the slice direction." }
q_MRAIIQUIZ_12	What causes the subclavian artery “pseudo-stenosis” artifact on CE-MRA?	[ 1 ]	[ "Compression of the subclavian artery by the subclavian vein", "Susceptibility effects due to residual gadolinium in the subclavian vein", "Turbulence at its junction with the axillary artery", "Reflux due to retrograde flow from the vertebral artery into the subclavian artery" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "A focal irregularity in the subclavian artery mimicking stenosis may occur ipsilateral to the side of contrast injection. This is a susceptibility (T2*) effect due to residual gadolinium in the adjacent subclavian vein, more commonly seen on the left side than right." }
q_MRAIIQUIZ_13	What is the cause of the ringing (Maki) artifact on CE-MRA?	[ 1 ]	[ "Gibbs (truncation) phenomenon", "Central region of k-space scanned before arrival of the contrast bolus", "Central region of k-space scanned too long after arrival of contrast bolus", "Vascular pulsation" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "If the central region of k-space is scanned before arrival of the contrast bolus, the vessel will appear dark in the middle, with only its edges demonstrating enhancement. Scanning too early produces this artifact originally described by Maki et al." }
q_MRFLOW_00	Bulk blood flow (Q) through a certain point in the vascular tree within a given period of time is measured in what units?	[ 3 ]	[ "cm/s", "cm/s²", "cm²/s", "cm³/s" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "Bulk flow is a volume per unit time and is expressed in units of cm³/s." }
q_MRFLOW_01	What is the approximate bulk blood flow (Q) passing through a 2 cm diameter artery where the average velocity is 50 cm/s?	[ 3 ]	[ "25 cm³/s", "50 cm³/s", "100 cm³/s", "160 cm³/s" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "The cross-sectional area (A) of the vessel is πr² = π (1 cm)² = 3.14 cm². So the bulk blood flow (Q) = V x A = 50 cm/sec x 3.14 cm² = 157 cm³/s." }
q_MRFLOW_02	In what part of a vessel is the blood flow the slowest?	[ 0 ]	[ "Adjacent to the wall of the vessel", "In the center of the vessel", "Half-way between the wall and center", "The blood flow is the same across the entire vessel." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "Near the vessel wall where fluidic shearing and frictional forces are greatest, the blood flow will be nearly zero. Centrally within the lumen, blood flow will be most rapid." }
q_MRFLOW_03	Which blood vessel normally demonstrates a prominent reversal of flow during the cardiac cycle?	[ 1 ]	[ "Vertebral artery", "Ascending thoracic aorta", "Middle cerebral artery", "Renal artery" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The thoracic aorta has prominent reversal of flow during diastole as the coronary circulation is filled. The brain and kidneys have low vascular resistance; thus, carotid and renal arterial vessels demonstrate high forward flows even during diastole." }
q_MRFLOW_04	Which blood vessel has the greatest peak velocity?	[ 0 ]	[ "Thoracic aorta", "Abdominal aorta", "Carotid artery", "Renal artery" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 1, "hint": "The ascending aorta has the highest average peak velocities of the major vessels; typical values are 150-175 cm/sec. Flow in the distal aorta and iliac vessels slows to the 100-150 range, whereas peak velocities in the proximal carotid, brachial, and superficial femoral arteries are about 80-110 cm/sec." }
q_MRFLOW_05	What happens to peak velocities as a vessel goes becomes increasingly stenotic?	[ 3 ]	[ "They decrease.", "They increase.", "They remain the same.", "They increase initially then decrease." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "As vessels become increasingly stenotic their peak velocities initially increase (due to the Bernoulli effect). In extremely high-grade stenosis, however, vascular resistance becomes so high that the flow rates and velocities fall just before total occlusion is reached." }
q_MRFLOW_06	In ideal laminar flow the distribution of velocities in cross-section across a vessel should be	[ 2 ]	[ "Linear", "Constant", "Parabolic", "Hyperbolic" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Laminar flow refers to a predictable distribution of flow velocities in layers (lamina) that parallel the vessel wall. Theoretically, the distribution of velocities in a perfectly straight, nonbranching vessel with nonpulsatile flow should be parabolic in cross-section." }
q_MRFLOW_07	In which anatomic situation would you not expect to find vortex flow?	[ 2 ]	[ "Distal to a carotid artery stenosis", "In the proximal (ascending) aorta", "In the distal thoracic aorta", "In an abdominal aortic aneurysm" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Vortex flow refers to localized swirling or stagnant blood flow that has separated from the central streamlines within a vessel. Such vortices, also called flow eddies, frequently occur at vascular bifurcations and distal to areas of stenosis. Vortex flow is prominent in the ascending aorta, as jets of blood are expelled and swirl around during each cardiac contraction. They are less likely in the distal thoracic aorta, so the correct answer is (c)." }
q_MRFLOW_08	Which statement about the Reynolds number (Re) in ideal fluids is true?	[ 3 ]	[ "Values of Re < 2000 predict turbulent flow.", "Values of Re > 2500 predict laminar flow.", "Re is a velocity with units of cm/sec.", "Re is a dimensionless parameter." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "The Reynolds number (Re) is a dimensionless parameter used to predict flow characteristics in ideal fluids. (Answer d is correct). Values of Re less than 2000 predict that flow will be laminar, whereas values greater than 2500 usually indicate that flow will be turbulent." }
q_MRFLOW_09	In which situation would you be more likely to see turbulent flow?	[ 1 ]	[ "In a vessel with a small diameter", "In a vessel with rapid blood velocities", "In a vessel with elevated blood viscosity", "In the stump of a newly occluded vessel" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "The probability of turbulent flow is proportional to the Reynolds number (Re), being directly proportional to blood velocity and vessel diameter, and inversely proportional to blood viscosity. So choice (b) is correct." }
q_MRFLOW_10	Which one of the following flow-related phenomena is considered a time-of-flight (TOF) effect?	[ 0 ]	[ "High intravascular signal in an entry slice.", "Signal loss due to in-plane flow within an imaging gradient.", "Signal loss due to turbulent flow in an aneurysm.", "High signal in a vessel due to gradient moment nulling." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "Time-of-flight (TOF) effects refer to signal variations resulting from the motion of protons flowing into or out of an imaging volume during a given pulse sequence. High intravascular signal in an entry slice (choice a) is a type of TOF known as flow-related enhancement. The other choices are all spin-phase effects." }
q_MRFLOW_12	Which statement concerning high-velocity signal loss (“washout”) is incorrect?	[ 2 ]	[ "High-velocity signal loss is considered a time-of-flight effect.", "It is typically seen in arteries and larger veins flowing perpendicular to the plane of imaging.", "It is seen primarily in gradient echo imaging sequences.", "It can occur anywhere in the imaging slab and is not confined to the end slices." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Answer (c) is incorrect. High-velocity signal loss is typically seen on spin-echo sequences where flowing blood must receive both 90° and 180° pulses to generate a signal. Gradient echo sequences use single RF-pulses with gradient refocusing." }
q_MRFLOW_13	The total phase gained by a proton moving for time (t) at constant velocity (v) through a constant gradient of strength (G) is proportional to	[ 1 ]	[ "t", "t²", "v²", "G²" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "The phase shift experienced by a moving spin will be proportional to its velocity, the strength of the applied gradient, and the square of the length of time it moves within that gradient." }
q_MRFLOW_14	A radiologist interpreting a head MRI in a patient with suspected stroke dictates: “A flow-void is noted in the basilar artery.” What does this mean?	[ 2 ]	[ "No blood flow is present in the basilar artery.", "Some flow in the basilar artery may be present, but it is very weak.", "The basilar artery contains flowing blood.", "A thrombus is present in the basilar artery." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "“Flow void” is a widely used term referring to low signal in vessels that contain vigorously flowing blood, and is due to a combination of time-of-flight and spin-phase effects. Although most specialists are familiar with this term, it has the potential for confusion among less sophisticated members of the health care team, who may falsely interpret it to mean absence of flow." }
q_MRFLOW_15	Which of the following statements is not a reason gradient echo sequences can be used to preserve or accentuate signal from flowing blood?	[ 0 ]	[ "Gradient refocusing of spins is slice-selective.", "Relatively short echo times possible with GRE minimize T2* dephasing.", "Sequential mode acquisition with GRE makes every slice an “entry slice” with flow-related enhancement.", "Moderate-to-large flip angles with GRE saturate stationary tissue and accentuate T2/T1 contrast of blood." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "All are true except (a). In routine SE imaging, at least part of the reason for flow-related signal loss is that spins move out of the section between the 90°- and 180°-(refocusing)-pulses. In GRE imaging the refocusing is done by means of a gradient reversal that is not slice-selective. This nonselective refocusing does not result in hyperintensity of incoming spins, however; it merely prevents them from experiencing TOF signal losses." }
q_MRFLOW_16	Which of the following is not a limitation of the flow compensation (gradient-moment nulling) technique?	[ 1 ]	[ "Increased minimum TE", "Increased energy deposition (SAR)", "Inability to correct for nonconstant velocities or acceleration", "Increased stress on gradients" ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 2, "hint": "All are true except (b). No extra RF pulses are used, just additional gradient lobes, so no additional energy is deposited by GMN." }
q_MRFLOW_17	In which situation would refocused misregistered flow signal most likely to be observed?	[ 3 ]	[ "In a vessel running parallel to the phase-encode axis.", "In a vessel running perpendicular to the phase-encode axis.", "In sequences with very short TE values.", "In sequences where flow compensation (gradient-moment nulling) is used." ]	{ "subject": "Cardiovascular and MRA Quiz", "level": 3, "hint": "Flow misregistration is most commonly seen for in-plane vessels running obliquely to the frequency and phase-encoding axes with long TE’s and the use of gradient-moment nulling." }
q_KQUIZ_00	A point in k-space corresponds to	[ 0 ]	[ "The amount of a particular spatial frequency in the entire imaged object", "The amount of a particular spatial frequency at a particular point in the imaged object", "The magnitude and phase of the signal arising from a particular point in the imaged object", "The spin density of the signal arising from the entire imaged object." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "K-space is an array of numbers representing spatial frequencies in the MR image. The individual points (kx,ky) in k-space do not correspond one-to-one with individual pixels (x,y) in the image. Each k-space point contains spatial frequency and phase information about every pixel in the final image." }
q_KQUIZ_01	Which of the following statements about k-space is false?	[ 3 ]	[ "The kx and ky axes of k-space generally correspond to the horizontal (x-) and vertical (y-) axes of the image.", "Each point in k-space contains spatial frequency and phase information about every pixel in the final image.", "Each pixel in the image maps to every point in k-space.", "Points near the center of k-space correspond to points in the center of the image." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Each point in k-space contains spatial frequency and phase information about every pixel in the final image. So choice (d) is false." }
q_KQUIZ_02	Which of the following statements about k-space is true?	[ 2 ]	[ "The center of k-space provides information about the edges and details of the imaged object.", "The periphery of k-space provides information about the general shape and contour of the object.", "The raw data at the exact center of k-space always has a larger magnitude than any other point.", "k-space must be filled with data in a specific order." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Only (c) is true. There are two reasons the central area of k-space has the largest magnitude. First, the central row (ky = 0) is acquired with no phase-encoding gradient (and hence no destructive wave interference caused by phase-encoding steps). Secondly, the central column of k-space (kx = 0) coincides with the peak of the MR echo." }
q_KQUIZ_03	In routine anatomic MR images, what points in k-space have the lowest amplitudes?	[ 0 ]	[ "The four corners", "The center", "The middle of the top and bottom edges", "The middle of the left and right edges" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Signals from the four corners have the highest spatial frequencies in both directions and correspond to data locations where the MR signals are weakest. For time-savings in spiral imaging, the four corners are often excluded from data sampling with only minimal loss of resolution noted." }
q_KQUIZ_04	The “k” of k-space refers to “wavenumber”, an index for spatial frequency, which is the number of waves or cycles per unit distance. An acceptable unit for “k” could therefore be	[ 1 ]	[ "Cycles per second", "mm−1", "cm/sec", "Line pairs" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "The wavenumber (k) is simply the reciprocal of the wavelength. Since the wavelength is measured in units of distance, the units for wavenumber are (1/distance), such as 1/mm = mm−1. Other acceptable units would include line pairs per mm and cycles per mm." }
q_KQUIZ_05	Which statement about the location of spatial frequencies in k-space is true?	[ 2 ]	[ "A point along the kx axis corresponds to horizontal stripes in the image", "A point along the ky axis corresponds to vertical stripes in the image", "A point at a 45º angle from the the kx axis corresponds to stripes at 45º in the image", "If the imaged object is small relative to the field-of-view, its k-space frequency representation will be mostly confined to the center." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Option (c) is true. Options (a) and (b) are reversed. Concerning incorrect choice (d), the physical size of the object imaged and its frequency expanse in k-space are inversely related. In other words, small objects have ripples far out into the periphery of k-space, while larger objects have their spectral energies more concentrated at the center." }
q_KQUIZ_06	Consider a conventional 2DFT spin-echo pulse sequence with frequency encoding along the x-axis and phase-encoding along the y-axis. Which statement is false?	[ 2 ]	[ "For a given phase-encode step (ky), digitized data from the early part of the echo is placed at the far left side of k-space (negative kx values).", "For a given phase-encode step (ky), digitized data from the early part of the echo is placed at the far right side of k-space (positive kx values).", "For a given phase-encode step (ky), digitized data from the peak of the echo is placed at the the point (kx=0, ky=0).", "For a given phase-encode step (ky), digitized data from the peak of the echo is placed at the the point (kx=0, ky)." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "Option (c) is false, while option (d) is true." }
q_KQUIZ_07	Concerning the filling of k-space by a conventional 2DFT spin-echo pulse sequence with frequency encoding along the x-axis and phase-encoding along the y-axis, which statement is false?	[ 1 ]	[ "The central point of k-space (kx=0, ky=0) corresponds to the constant term in the Fourier representation of the image.", "Except for the central row (ky=0), each row of k-space is acquired with the same constant value of the phase-encoding gradient.", "The central row (ky=0) of k-space is acquired with no phase-encoding gradient.", "The central column of k-space (kx=0) coincides with the peak of the MR echo for each phase-encoding step." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Option (b) is false. In 2DFT spin-echo imaging, the phase encoding gradient is stepped in magnitude from cycle to cycle, not held constant. The other statements are correct." }
q_KQUIZ_08	The row-by-row filling of k-space by a conventional 2DFT spin-echo pulse sequence is often referred to as what trajectory?	[ 0 ]	[ "Cartesian", "Radial", "Zig-Zag", "Blipped" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Traditionally the Cartesian (row-by-row) method was used nearly exclusively for all pulse sequences, but today many different patterns are widely encountered." }
q_KQUIZ_10	The non-uniform raw data from a radial or spiral acquisition must be placed into a rectangular (Cartesian) matrix format for efficient computations. This process is referred to as	[ 1 ]	[ "Morphing", "Gridding", "Pigeon-holing", "Compressing" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "“Gridding“ is the commonly used term for this process. Although various methods exist, the typical gridding algorithm first involves multiplication of original data with a set of density compensation weights and convolution with a gridding kernel. The resultant data is then interpolated and placed into the uniformly spaced matrix (the \"grid\") where a discrete Fourier transform is performed. Finally, the field-of-view is trimmed and the transformed data multiplied by an apodization correction function." }
q_KQUIZ_11	How many phase cycles are needed to uniquely differentiate each pixel along a certain direction in an image?	[ 1 ]	[ "0,5", "1", "1", "2" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "One full phase cycle is needed to uniquely differentiate each pixel. If there are N pixels of width (Δw) spanning the field-of-view (FOV), then N phase cycles are needed." }
q_KQUIZ_12	If the data sampling rate is halved in the frequency-encode direction (x), what happens to the spacing (Δkx) between points in k-space?	[ 2 ]	[ "It remains unchanged.", "It is halved.", "It is doubled.", "It is quadrupled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "This is equivalent to sampling every other kx value, so compared to the original pattern, the spacing Δkx) will double Link to Q&A discussion" }
q_KQUIZ_13	If the data sampling rate is halved in the frequency encode direction (x), what happens to the field of view in that direction?	[ 1 ]	[ "It remains unchanged.", "It is halved.", "It is doubled.", "It is quadrupled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "We use the formula Δk = 1/FOV. So doubling Δk means the FOV is halved." }
q_KQUIZ_14	If the data sampling rate is halved in the frequency encode direction (x), what happens to the pixel size in that direction?	[ 0 ]	[ "It remains unchanged.", "It is halved.", "It is doubled.", "It is quadrupled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "The pixel width Δw = 1/ kFOV. As long as the kFOV = 2kmax is unchanged, the pixel width will remain unchanged also." }
q_KQUIZ_15	Supposed the data sampling rate in the frequency encode direction (x) is unchanged, but the sampling time is reduced so that only the central ⅓ of k-space is sampled. What happens to the pixel width and FOV in that direction?	[ 0 ]	[ "The pixel size is tripled and the FOV is unchanged.", "The pixel size is unchanged and the FOV is tripled.", "Both the pixel size and FOV are reduced by ⅓.", "Both the pixel size and FOV are tripled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Because the data sampling rate is unchanged, Δkx is unchanged and the points are spaced out as before. So since Δk = 1/FOV, the FOVx is unchanged. By sampling only the center ⅓ of k-space, the kFOV is now only ⅓ as large. And since pixel width Δw = 1/ kFOV, this means the pixel width has tripled. Hence answer (a) is correct." }
q_KQUIZ_16	Suppose that the frequency encoding portion of the 2D spin warp imaging was left alone, but the number of phase-encoding steps was cut in half (while leaving the maximum and minimum amplitudes of the phase-encoding gradient unchanged). What happens to the spacing (Δky) between points in the phase-encode direction (y)?	[ 2 ]	[ "It remains unchanged.", "It is halved.", "It is doubled.", "It is quadrupled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "Cutting the number of phase encode steps (Ny) in half in this scenario doubles the increment between successive steps, so Δky is doubled." }
q_KQUIZ_17	In the question above, what does the phrase “while leaving the maximum and minimum amplitudes of the phase-encoding gradient unchanged” mean in terms of kFOV in the y-direction?	[ 0 ]	[ "It remains unchanged.", "It is halved.", "It is doubled.", "It is quadrupled." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "The phrase basically stipulates that kFOV is unchanged." }
q_KQUIZ_18	Continuing on with the same scenario as in questions 17 and 18, what happens to the pixel width and the phase FOV?	[ 3 ]	[ "The pixel size is doubled and the FOV is unchanged.", "The pixel size is unchanged and the FOV is doubled.", "Both the pixel size and FOV are halved.", "The pixel size is unchanged and the FOV is halved." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "The scenario in these last three questions is to create a rectangular field of view with a 1:2 frequency:phase ratio. Because Δky is doubled, the FOVy is halved. Furthermore, because both the FOVy and Ny have been reduced by one-half, pixel size in the phase-encode direction (FOVy/ Ny) and overall spatial resolution of the image are also unchanged." }
q_KQUIZ_19	Concerning obtaining a rectangular field of view by reducing the number of phase encoding steps as described above, which of the following statements is false?	[ 2 ]	[ "This option is most beneficial when imaging the spine and extremities.", "Spatial resolution is unchanged.", "Signal to noise ratio is unchanged.", "Wrap-around artifacts in the phase-encode direction are more likely to occur." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Option (c) is false. Because fewer phase-encoding steps and hence fewer echo signals are acquired, the signal-to-noise ratio (SNR) is proportionately lower compared to full FOV imaging." }
q_KQUIZ_20	Provided no phase errors occur during data collection, what type of symmetry does k-space exhibit?	[ 3 ]	[ "x-axis symmetry", "y-axis symmetry", "z-axis symmetry", "conjugate symmetry" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "Provided no phase errors occur during data collection, k-space possesses a peculiar mirrored property known as conjugate (or Hermitian) symmetry." }
q_KQUIZ_21	Which statement concerning phase-conjugate symmetry (partial Fourier) imaging is false?	[ 0 ]	[ "Over 50% savings in imaging time can be achieved by the use of this technique.", "More than half of the phase-encoding lines must be sampled to correct for phase errors.", "Spatial resolution is preserved.", "For half-Fourier imaging, signal-to-noise is reduced by about 30%." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Phase-conjugate symmetry techniques use data from the top half of k-space to estimate data in the lower half of k-space. In theory, phase-conjugate symmetry allows one to acquire data using only half the normal number of phase-encoding steps, thus potentially reducing imaging time by up to one-half. However, to correct for phase errors, more than half of the phase-encoding lines must be sampled, so the actual time savings is less than 50%." }
q_KQUIZ_22	Which statement concerning read-conjugate symmetry imaging is false?	[ 2 ]	[ "There is no direct time savings.", "Flow and motion artifacts along the frequency-encode direction are reduced.", "Only the first part of the echo is sampled.", "The technique allows for shorter TE values." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "The direction of read-conjugate symmetry is along the readout (frequency-encode) axis. Only the last part of the echo is sampled, so choice (c) is false. The other statements are true." }
q_KQUIZ_23	Which of the following statements about zero filling is false?	[ 1 ]	[ "It may be used either for 2D or 3D imaging", "It is used to expand the imaging matrix in the frequency-encoded direction", "It improves the apparent spatial resolution of the image.", "After the first doubling of matrix size with zeros, no added benefit is realized." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Zero-filling is routinely used to expand the image matrix size in the phase-encoded direction, which may be either within-plane (2D) or through-plane/slab select (3D). Zero filling acts as method to interpolate the signals from neighboring voxels, giving the image a smoother and less \"pixel-ly\" appearance." }
q_PIQUIZ_00	Which of the following statements about parallel imaging is false?	[ 2 ]	[ "It can be used with virtually all pulse sequences.", "It requires multiple receiver coils.", "It can be performed in any direction.", "Its primary purpose is to reduce the number of required phase-encoding steps." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "The allowed direction(s) in which PI can be performed depends on the arrangement of coils in the array. Specifically, the coils must should have different sensitivity profiles along the direction chosen for PI. PI cannot not be used with just a single surface, head, knee, or large body coil having only one pair of quadrature output channels." }
q_PIQUIZ_01	Which of the following is not a disadvantage of parallel imaging?	[ 0 ]	[ "Increased susceptibility artifacts.", "Increased aliasing artifacts.", "Coil calibration artifacts.", "Increased noise in a non-uniform fashion with reduced SNR." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Phase-related distortions in the MR signal due to susceptibility are reduced (not increased) by the PI acquisition and reconstruction process. This is especially advantageous in echo-planar sequences." }
q_PIQUIZ_02	Comparing image domain PI techniques (like SENSE/ASSET) and k-space PI techniques like (GRAPPA/ARC), which statement is false?	[ 1 ]	[ "For high R(acceleration)-values, image domain PI techniques provide slightly higher SNR.", "Image domain PI performs better in heterogeneous body regions (like the chest)", "K-space PI techniques display less aliasing and are more useful when small FOVs are needed.", "K-space PI techniques are more effective at minimizing susceptibility distortions." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "Image domain PI techniques like SENSE/ASSET perform poorly in heterogenous body regions. This is because accurate coil sensitivity maps may difficult to obtain. The lungs are a prime example." }
q_PIQUIZ_03	What is the proper order of steps in acquiring an image-domain PI image (like SENSE/ASSET)? Abbreviations: A = Acquire partial k-space data; G = Generate coil sensitivity maps; R = Reconstruct individual coil images; U = Unfold/combine partial FOV images.	[ 2 ]	[ "A — G — R — U", "G — A — U — R", "G — A — R — U", "A — G — U — R" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "The proper order is Generate/Acquire/Reconstruct/Unfold (c)." }
q_PIQUIZ_04	What is the proper order of steps in acquiring an k-space PI image (like GRAPPA/ARC)? Abbreviations: A = Acquire partial k-space data; C = Combine data into magnitude image; E = Estimate missing k-space lines; G = generate individual coil images	[ 1 ]	[ "A — C — E — G", "A — E — G — C", "E — A — G — C", "E — A — C — G" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "The proper order is Acquire/Estimate/Generate/Combine (b)." }
q_PIQUIZ_05	Which of the following statements about CAIPIRINHA sequence is false?	[ 0 ]	[ "It can be classified as an image-domain PI technique.", "Acceleration factors (R) of 4 are typical.", "It is most commonly used for 3D dynamic liver imaging.", "It uses shifting k-space sampling patterns to reduce pixel aliasing and overlap." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "CAIPIRINHA is clearly a k-space (not image domain) PI technique, as it depends on k-space data sampling and manipulation prior to reconstruction." }
q_PIQUIZ_06	What happens to the imaging time in a PI study as the acceleration factor (R) is increased from 2 to 8?	[ 0 ]	[ "It decreases by a factor of 4", "It decreases by a factor of 2", "It decreases by a factor of √2", "It decreases by a factor of 1/√2" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 1, "hint": "Imaging time is inversely related to R, so if R quadruples (from 2 to 8), the imaging time is reduced by a factor of 4 Link to Q&A discussion" }
q_PIQUIZ_07	What happens to the signal-to-noise ratio (SNR) in a PI study as the acceleration factor (R) is increased from 2 to 8?	[ 1 ]	[ "It decreases by a factor of 4", "It decreases by a factor of 2", "It decreases by a factor of √2", "It decreases by a factor of 1/√2" ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 2, "hint": "SNR is inversely related to √R, so if R quadruples (from 2 to 8), the SNR is reduced by a factor of √4 = 2." }
q_PIQUIZ_08	Which statement about the g-factor is false?	[ 3 ]	[ "It depends on the number and location of coils.", "It depends on the direction of phase-encoding", "It varies by location across the image.", "Typical values range from about 10 to 100." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "The g-factor depends on 1) number and location of surface coils, 2) coil loading, 3) plane of imaging, 4) direction of phase-encoding within the scan plane, and 5) voxel location within the imaged region. With typical coil designs in common use, g-factors ranging from 1.0 to 2.0 across the imaging volume are commonly measured." }
q_PIQUIZ_09	The g-factor in the middle of a homogenous phantom imaged with PI is 2.0 while that near its periphery is 1.0. How do the SNR of the center and periphery compare?	[ 0 ]	[ "SNR (center) is one-half as large as SNR (periphery).", "SNR (center) is equal to SNR (periphery).", "SNR (center) is twice as large as SNR (periphery).", "SNR (center) is four times as large as SNR (periphery)." ]	{ "subject": "K-space and Rapid Imaging Quiz", "level": 3, "hint": "SNR is inversely related to the g-factor, so if the g-factor doubles, the SNR is only ½ as large." }

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MRI-MCQA

Dataset Description

MRI-MCQA is a benchmark composed by multiple-choice questions related to Magnetic Resonance Imaging (MRI). We use this dataset to evaluate the level of knowledge of various LLMs about the MRI field.