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HPAI-BSC
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MRI-MCQA

Dataset card Data Studio Files
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q_5_21
Which of the following statements about MR scanner noise is false
[ 1 ]
[ "Sound levels can reach up to 120 dB for some sequences.", "Although potentially uncomfortable for the patient, there is no real risk to hearing.", "Ear protection is mandatory for all patients undergoing MR imaging.", "New quiet pulse sequences can reduce noise levels to within 10 dB of background." ]
{ "subject": "Magnets & Scanners Quiz", "level": 1, "hint": "Sound levels indeed can reach 120 dB for some sequences, especially echo-planar ones. This can result in damage to the inner ear and produce hearing loss, so option b) is false. Thus ear protection is mandatory for all patients." }
q_5_22
Which of the following methods can reduce scanner noise?
[ 3 ]
[ "Avoidance of echo-planar sequences", "Use of \"soft\" gradient pulses with longer rise times", "Use of 3D ultrashort TE sequences", "All of the above" ]
{ "subject": "Magnets & Scanners Quiz", "level": 2, "hint": "These strategies will all produce a reduction of noise levels during scanning." }
q_5_23
Newer "quiet" MR sequences with longer gradient ramp times are now available. Which of the following statements about these sequences is true
[ 0 ]
[ "They can reduce noise levels to within 10 dB of background.", "This strategy can be applied to all pulse sequences.", "They can be employed with no signal-to-noise penalty.", "They do not affect number of slices for a given TR." ]
{ "subject": "Magnets & Scanners Quiz", "level": 2, "hint": "Newer quiet sequences can reduce noise levels to less than 10 dB of background, so answer a) is true. They can be used on many (but not all) pulse sequences. Because of the increasing rise and fall times there is a shorter sampling window and SNR is reduced. A penalty in the maximum number of slices may also occur at constant bandwidth due to the increased time spent in ramping gradients." }
q_5_24
Radiofrequency shielding of the scanner room is most commonly achieved by lining the walls with thin sheets of
[ 2 ]
[ "Iron", "Aluminum", "Copper", "Lead" ]
{ "subject": "Magnets & Scanners Quiz", "level": 1, "hint": "A thin layer of copper around the entire room is most commonly used in scanner installations. It acts as a Faraday cage and is effective at reducing penetration of extraneous radiofrequencies. However, virtually any conductive metal could be used for this purpose, and both steel and aluminum cages are occasionally used. Link to Q&A discussion" }
q_5_25
The primary purpose for radiofrequency shielding is
[ 2 ]
[ "To confine fringe fields to the scanner room itself.", "To constrain the NMR signal to remain within the bore of the magnet for better reception", "To keep extraneous radiofrequency noise from entering the scanner room", "To reduce the effects of moving equipment (such as cars and elevators) from distorting the magnetic field." ]
{ "subject": "Magnets & Scanners Quiz", "level": 1, "hint": "RF-shielding primarily prevents extraneous radiofrequency noises from outside the scanner room from entering and contaminating the MR signal." }
q_5_27
A device that allows a plastic oxygen hose to be passed through the wall of an MR scanner room without disrupting the integrity of the RF-shielding is called a
[ 2 ]
[ "Penetration panel", "Bandstop filter", "Waveguide", "Faraday cage" ]
{ "subject": "Magnets & Scanners Quiz", "level": 2, "hint": "The correct answer is waveguide (c). This looks like a pipe mounted within the wall and has a design that it blocks/traps radiofrequencies in the Larmor frequency range from passing through. This device is commonly part of the penetration panel, which also includes bandstop filters for wires. The Faraday cage is the entire enclosure around a scanner room to produce RF shielding." }
q_5_28
A common location for RF-leakage into the scanner room is
[ 0 ]
[ "Around the door", "Along seals of the scanner window", "At the penetration panel", "Along the junction of copper plates in the scanner room’s walls" ]
{ "subject": "Magnets & Scanners Quiz", "level": 2, "hint": "Because of repetitive opening and closing, RF-seals around the door are frequently damaged and a common source of RF-leakage into the room." }
q_FEPEQUIZ_00
What are the units for angular frequency (ω)?
[ 3 ]
[ "Hertz (Hz)", "Cycles per second (cps)", "Radians per cycle", "Radians per second" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "Angular frequency (ω), also known as radial or circular frequency, measures angular displacement per unit time. Its units are therefore degrees (or radians) per second." }
q_FEPEQUIZ_01
Approximately how many degrees are in one radian?
[ 2 ]
[ "30.0º", "45.0º", "57.3º", "71.7º" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "By definition, 2π radians span the arc of one circle, or 360º. So 1 radian = 360/2π ≈ 57.3º" }
q_FEPEQUIZ_02
A 180º-pulse is sometimes expressed using radians as a
[ 1 ]
[ "π/2-pulse", "π-pulse", "3π/2-pulse", "2π-pulse" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "A 180º-pulse is half a circle, or a π-pulse." }
q_FEPEQUIZ_03
As gradients are turned on and off, the angular frequency (ω) of a spin changes with time (t), expressed by the function ω(t). The area under the graph of ω(t) vs t between two time points (A and B) represents
[ 0 ]
[ "The spin’s accumulated phase shift between A and B", "The spin’s change in frequency between A and B", "The energy acquired by the spin between A and B", "The change in field strength experienced by the spin between A and B" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The area under the ω(t) vs t curve represents the accumulated phase of the spin during a certain interval. From a unit perspective, frequency is measured in radians or degrees per second while time is measured in seconds, so their product [ω(t) x t] will have units of radians (or degrees)." }
q_FEPEQUIZ_04
The MR signal information received by the RF-coil can be classified as
[ 1 ]
[ "Frequency modulated", "Amplitude modulated", "Phase modulated", "Pulse modulated" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "MR signal information, typically encoded over a range of 50-100kHz, arrives at the receiver amplitude-modulated on the RF carrier wave (e.g. at 64 MHz). The first step in signal process is called demodulation, which removes the carrier." }
q_FEPEQUIZ_05
The real and imaginary components during of an MR signal in the I and Q channels of a receiver are measured at a specific time point to be 3.0 and 4.0 au (arbitrary units) respectively. What is the actual magnitude of the signal?
[ 1 ]
[ "3.5 au", "5.0 au", "7.0 au", "12.0 au" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "The magnitude (M) = [Re² + Im²]½ = [3² + 4²]½ [25]½ = 5.0 au." }
q_FEPEQUIZ_06
Concerning Fourier representation of the MR signal, which of the following statements is false?
[ 2 ]
[ "The Fourier expansion of a signal can be written in either trigonometric or exponential form.", "To represent any real signal exactly, an infinite number of frequency components must be included in its Fourier representation.", "The Fourier transformation converts a time-based signal into the frequency domain, but the change cannot be reversed.", "The Fourier series representation of an MR image is always cut short (truncated)." ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "All are true except for (c). Fourier transformation is the mathematical procedure connecting a time domain signal, s(t), and its frequency domain representation, S(ω). The inverse Fourier transform converts S(ω) back to s(t)." }
q_FEPEQUIZ_07
The time domain signal, s(t), that corresponds to a uniform/rectangular band of frequencies in S(ω) is called a
[ 1 ]
[ "Double exponential", "Sinc function", "Gaussian", "Lorentzian" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "The sinc function, sinc(t) = [sin t]/t, Fourier transforms into a uniform band of frequencies, such as those used to define a slice profile in conventional 2D MR imaging Link to Q&A discussion" }
q_FEPEQUIZ_08
Which of the following scientists did not win the Nobel Prize for their work in NMR?
[ 1 ]
[ "Felix Bloch", "Raymond Damadian", "Paul Lauterbur", "Peter Mansfield" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Raymond Damadian did not win the Nobel Prize for his work and considered it a personal injustice. He placed full-page ads in several large world newspapers urging the Nobel committee to change their minds, which they never did." }
q_FEPEQUIZ_09
Which of the following is not a method for spatial localization of the MR signal?
[ 3 ]
[ "Frequency encoding", "Phase encoding", "Location of receiver coils", "Amplitude modulation" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Choice (d), amplitude modulation, refers to the shape of transmitted or received RF-pulses but is not by itself a method of spatial localization." }
q_FEPEQUIZ_10
Which of the following statements about frequency encoding is incorrect?
[ 1 ]
[ "It commonly used for in-plane localization for 2D imaging.", "It is commonly used for slice selection in 3D imaging.", "Each voxel actually contains a range of frequencies, not just a single frequency.", "For most applications a linear frequency encoding gradient is desired." ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "All are correct except (b). Frequency encoding is commonly used for slice selection in 2D imaging, but phase encoding is typically used for slice selection in 3D." }
q_FEPEQUIZ_11
What is a typical total receiver bandwidth for a 1.5T MR scanner?
[ 1 ]
[ "1 kHz", "50 kHz", "250 kHz", "500 kHz" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Receiver bandwidth is an operator-selectable parameter, chosen by the technologist before the scan begins. Available values for total receiver BW range from about 5-100 kHz with 50kHz being typical." }
q_FEPEQUIZ_12
What is the width of a pixel in the frequency encoding direction if the field-of-view is 25.6 cm and 512 frequency-encoding steps are used?
[ 0 ]
[ "0.5 mm", "1.0 mm", "2.0 mm", "5.0 mm" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Pixel width = FOVf ÷ # frequency encode steps = 256 mm ÷ 512 = 0.5 mm." }
q_FEPEQUIZ_13
If 256 complex measurements of a digitized MR signal are sampled in a period of 5.12 ms, what is the dwell time?
[ 2 ]
[ "5 μs", "10 μs", "20 μs", "200 μs" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "The dwell time is the interval between digitized samples. So if 256 samples were obtained over a 5.12 ms period, the dwell time would be 5.12 ms/256 = 20 μs." }
q_FEPEQUIZ_14
What is the total receiver bandwidth if the interval between digitized samples (dwell time) is 25 μs?
[ 2 ]
[ "2,500 Hz", "25,000 Hz", "40,000 Hz", "50,000 Hz" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "Total receiver BW is the same as the digitization rate of the MR signal. In equation form, BW = 1/td = 1/(25 μs) = 40,000 Hz." }
q_FEPEQUIZ_15
In clinical MR imaging at 1.5T, what frequency range would be typical for setting the receiver to “narrow bandwidth”?
[ 1 ]
[ "1 – 5 kHz", "5 – 20 kHz", "50 – 52 kHz", "100 – 101 kHz" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "A typical range for narrow receiver bandwidth would be choice (b), 5 – 20 kHz." }
q_FEPEQUIZ_16
Which of the following statements about narrow bandwidth is incorrect?
[ 0 ]
[ "Narrow BW implies reduced sampling time.", "Narrow BW increases signal-to-noise.", "Narrow BW accentuates chemical shift artifacts.", "Narrow BW accentuates susceptibility artifacts." ]
{ "subject": "Making an Image Quiz", "level": 1, "hint": "Option (a) is false. Bandwidth is inversely proportional to sampling time. A synonym for \"narrow bandwidth\" is therefore \"extended sampling time\"." }
q_FEPEQUIZ_17
Which of the following statements about transmitter bandwidth is true?
[ 1 ]
[ "It is automatically determined once receiver bandwidth is specified.", "Transmitter BW per se is not directly adjusted by the technologist when specifying scan parameters.", "Typical values for transmit BW are 50-100 kHz.", "Most modern RF-pulses for 2D slice-select are sinc-shaped." ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The transmit bandwidth is not usually user-adjustable, so choice (b) is true. Typical values are 1000-2000 Hz and are independent of receiver bandwidth. Simple sinc pulses are no longer used for slice select, being supplanted by more sophisticated designs using the SLR algorithm." }
q_FEPEQUIZ_18
Cross-talk can be reduced by all of the following methods except:
[ 1 ]
[ "Increasing gaps between slices", "Increasing the strength of the slice-select gradient", "Performing slice interleaving", "Improving the RF slice profile" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Increasing the strength of the slice-select gradient will only serve to produce thinner slices, not improve cross-talk." }
q_FEPEQUIZ_19
The earliest commercial version of simultaneous slice excitation (offered by GE in the 1990s) applicable to single-channel RF coils was called
[ 0 ]
[ "Phase Offset MultiPlanar (POMP)", "MultiBand (MB)", "Simultaneous Multi-Slice (SMS)", "HyperBand (HB)" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The historical precursor to modern MB/SMS methods was POMP (Phase Offset MultiPlanar) imaging. The POMP technique used a composite RF-pulse to simultaneously excite two slices, each of which were phase-encoded over only one-half of the total field-of-view (FOV). Phase alternation allowed the two slices to be separately reconstructed without overlap. Unlike SMS, POMP does not utilize parallel imaging technology and is hence applicable to single-channel RF coils." }
q_FEPEQUIZ_20
Which of the following statements about MultiBand/Simultaneous Multi-Slice imaging is false?
[ 3 ]
[ "Use of parallel imaging arrays is required.", "Acceleration factors of 2-4 are typical.", "The slices must be widely spaced apart (2-3 cm).", "The technique imposes a significant penalty in terms of signal-to-noise." ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "MB uses coil encoding together with either gradient- or RF-encoding to resolve data along the slice-select (z)-axis. Because modern coil arrays typically have only a few coil elements in the z-direction, coil sensitivity differences along that axis are rather poor. Accordingly the simultaneously excited slices must be spaced widely apart (typically at least 25−30 mm). Unlike standard parallel imaging acceleration techniques, MB/SMS acceleration results in little to no penalty in signal-to-noise. (Option d is false). This is because neither the echo train length, number of phase-encoding steps, nor number of k-space samples has been reduced as occurs in conventional parallel imaging acceleration methods." }
q_FEPEQUIZ_21
What is the approximate in-plane pixel dimensions of a 25 x 25 cm FOV image acquired using 192 phase-encoding steps and 512 samples in the frequency direction
[ 0 ]
[ "1.3 x 0.5 mm", "2.6 x 0.5 mm", "1.3 x 5.0 mm", "2.6 x 5.0 mm" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "The pixel width in the phase encode direction is 250 mm ÷ 192 ≈ 1.3 mm, while that in the frequency encode direction is 250 ÷ 512 ≈ 0.5 mm." }
q_FEPEQUIZ_22
Concerning 2D Fourier Transform imaging, which statement is false
[ 1 ]
[ "The number of unique echo signals equals the number of phase-encoding steps.", "The phase shifts between successive echoes are multiples of 180º.", "For low-amplitude phase-encodings the MR signal is strong but provides little information about spatial detail.", "For high-amplitude phase-encodings the MR signal is weak and provides little information about image contrast." ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "Choice (b) is false. The phase shifts between the rows are not simple multiples of 180°, but vary from echo to echo depending on the size of the phase-encoding step. The number of echo signals acquired equals the number of phase encode steps, which is usually 192 or 256. For low order phase-encodings, the MR signal is strong. The frequency projection approximates the general shape of the object but lacks edge definition. The higher order phase encode steps have smaller MR signals but provide more information about spatial detail, such as the location of edges." }
q_FEPEQUIZ_23
Why is the phase-encode direction often chosen along the shortest anatomic dimension?
[ 0 ]
[ "This reduces wrap-around artifact.", "This reduces flow-related artifact.", "This reduces artifacts from gross patient motion.", "It is a requirement for parallel imaging." ]
{ "subject": "Making an Image Quiz", "level": 1, "hint": "Wrap-around (also called aliasing) occurs when the size of the body part imaged exceeds the defined field-of-view (FOV) in the phase-encode direction. This causes anatomy outside the FOV to be folded in over the main part of the image. To avoid wrap-around the phase-encoding direction is usually chosen to be along the shortest anatomic dimension. Flow-related and other motion artifacts may be moved around by changing the phase-encode direction, but the best direction is based on the location and types of these artifacts, which may or may not be best along the shortest dimension. For parallel imaging there may be some restrictions on possible phase-encode directions allowed, but setting phase-encode along the shortest axis is not necessarily required." }
q_SCQUCON_00
Which steps in setting up an MR scan are in the proper chronological order?
[ 2 ]
[ "Set landmark → Perform prescan → Acquire localizer → Position slices", "Acquire localizer → Position slices → Set landmark → Perform prescan", "Set landmark → Acquire localizer → Position slices → Perform prescan", "Perform prescan → Acquire localizer → Set landmark → Position slices" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Choice (c) shows the correct order." }
q_SCQUCON_01
Which process in the list below is not a part of automatic prescan?
[ 0 ]
[ "Specific Absorption Rate (SAR) estimation", "Quick shimming", "Center frequency adjustment", "Transmitter gain adjustment" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Specific Absorption Rate (SAR) is estimated by the scanner based on the patient’s body weight, pulse sequence, and pulse sequence parameters selected. This occurs before automatic prescan, allowing the operator to adjust parameters to keep SAR within established limits. Automatic prescan is essentially the last step before the actual scan begins." }
q_SCQUCON_02
In which of the following situations is manual shimming (in addition to prescan quick shimming) nearly always required?
[ 1 ]
[ "Diffusion-weighted imaging", "MR Spectroscopy", "Fast-spin echo imaging", "Dixon fat-water imaging" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Very detailed high-order shimming is mandatory for spectroscopy. Although spectroscopy shimming can be automated, the settings always require review and often tweaking by the MR technologist." }
q_SCQUCON_03
In which of the following situations is center frequency adjustment most critical?
[ 3 ]
[ "When using spatial saturation pulses", "When using flow saturation pulses", "When using arterial spin labeling pulses", "When using fat saturation pulses" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The center frequency may be set on water protons, fat protons, or some average of the two. Accurate center frequency setting is particularly important when spectral fat saturation pulses are employed to make sure the fat peak is adequately suppressed." }
q_SCQUCON_04
What artifact will occur if the receiver attenuator value is set too low during prescan?
[ 0 ]
[ "Data clipping", "Wrap around", "Ghosts", "Diffuse noise" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "If the attenuator value is set too low (i.e., receiver gain is set too high), then the signal will overload the analog-to-digital converter, and data clipping will occur. Since the largest peaks of the MR signal typically are the low order phase-encode steps at the center of k-space, data clipping interferes with image contrast. The result is an image with an \"eerie\" appearance" }
q_SCQUCON_05
What is the purpose of dummy cycles during prescan?
[ 3 ]
[ "To adjust RF-voltage to achieve a perfect 90º-pulse", "To allow warm-up of the transmit and receive circuitry", "To optimally match coil impedance with that of the patient", "To allow steady state longitudinal and transverse magnetization to be established" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "Once RF-excitation begins, the longitudinal and transverse magnetizations need time to reach their steady-state values. During prescan the scanner plays out several cycles of the sequence without recording a signal. These are called dummy cycles, disabled, or discarded acquisitions (DDA). The precise number of dummy cycles depends on the TR and the sequence chosen. Only once the system is near equilibrium does data collection begin." }
q_SCQUCON_06
To sell an MR scanner in the United States, a company must receive what kind of premarket clearance from the Food and Drug Administration?
[ 1 ]
[ "401(k)", "501(k)", "1099", "457(b)" ]
{ "subject": "Making an Image Quiz", "level": 4, "hint": "In the United States the Food and Drug Administration (FDA) has statutory authority to regulate the sale and use of MRI equipment. MRI scanners are considered Class II devices, meaning that they have the potential for human harm and require pre-market 501(k) clearance prior to marketing. The FDA has issued guidance documents with non-binding (but strongly suggested) criteria — including those related to hardware, software, performance, site planning, and safety — to attain this premarket approval. The other numbers are all IRS forms and investment accounts unrelated to MRI Link to Q&A discussion" }
q_SCQUCON_07
Which of the following organizations does not offer MRI accreditation in the United States?
[ 1 ]
[ "American College of Radiology (ACR)", "Centers for Medicare & Medicaid Services (CMS)", "RadSite", "The Joint Commission (TJC)" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "In the US there are four MRI accrediting organizations that are currently sanctioned by the Centers for Medicare & Medicaid Services (CMS) – the American College of Radiology (ACR), the Intersocietal Accreditation Commission (IAC), The Joint Commission (TJC), and RadSite." }
q_SCQUCON_08
Which of the following quality control measurements must be performed at least weekly on an MR scanner?
[ 0 ]
[ "Center frequency", "Magnetic field homogeneity", "Slice thickness accuracy", "Monitor resolution" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "Daily QC activities include visual inspection of all scanner hardware, the function of safety and communication devices, and general assessment of image quality including identification of artifacts. On at least a weekly basis, a special MR phantom is placed in the scanner and various measurements are made and recorded. Such measurements include landmark accuracy (table position), center frequency, image uniformity, transmitter gain or attenuation, geometric distortion, spatial resolution, artifact evaluation, and signal-to-noise ratio. Other more sophisticated testing should be performed semiannually or yearly by a medical physicist." }
q_SCQUCON_09
The most common cause of geometric errors is
[ 2 ]
[ "Warping of the MR phantom", "Abnormal RF-coil impedance", "Miscalibration of one or more imaging gradients", "Center frequency drift" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The most common cause of geometric errors is miscalibration of one or more imaging gradients. Gradients tend to drift over time and require periodic re-calibration by service engineers. Occasionally the problem is caused by Bo inhomogeneity due to improper shim adjustments or an occult ferromagnetic object lodged in the scanner bore." }
q_SCQUCON_10
Detailed procedures and standards for the two most commonly used methods of measuring signal-to-noise in a phantom come from which organization?
[ 0 ]
[ "The National Electrical Manufacturers Association (NEMA)", "The International Electrotechnical Commission (IEC)", "The International Commission on Non-Ionizing Radiation Protection (ICNIRP)", "The American Society for Testing and Materials (ASTM International)" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "The National Electrical Manufacturers Association (NEMA) provides detailed methods and standards for evaluating all types of electrical devices. Those relating specifically to MRI quality include how to measure signal-to-noise (MS 1, 6, & 9), geometric distortion (MS 2 & 12), and uniformity (MS 3)." }
q_SCQUCON_11
When complex-valued MR signal data is converted into a magnitude image, the noise statistics are best described using a
[ 3 ]
[ "Gaussian (normal) distribution", "Poisson distribution", "Gamma distribution", "Rician distribution" ]
{ "subject": "Making an Image Quiz", "level": 3, "hint": "Because region-of-interest (ROI) measurements are typically made on magnitude-reconstructed images, some correction to the statistics must take place. Recall that \"raw\" MR data is a complex number with real and imaginary parts. When converted to a magnitude only image, the pixel values corresponding to noise are no longer Gaussian, but skewed into a so-called Rician distribution." }
q_SCQUCON_12
The section of an MR phantom consisting of closely spaced lines or holes containing material with strong difference in signal intensity from the background is used to measure
[ 2 ]
[ "Low-contrast object detectability", "Geometric distortion", "High-contrast spatial resolution", "Image uniformity" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The high-contrast portion of MR phantoms contains closely spaced lines, edges, or holes containing material with strong differences in signal intensity from background. Low-contrast resolution refers to the ability to identify small holes in the phantom with only slightly different relaxation times from background." }
q_SCQUCON_13
The section of an MR phantom consisting of triangular ramps or wedges oriented at a known angle is used to measure
[ 0 ]
[ "Slice thickness", "Slice position", "Linear accuracy", "Low-contrast resolution" ]
{ "subject": "Making an Image Quiz", "level": 2, "hint": "The most common method to estimate slice thickness is to use a phantom containing triangular ramps or wedges whose surfaces are oriented at a known angle (θ) to the plane of the slice. When a slice passes through the ramp, it produces a stretched \"shadow\" image whose full width half maximum (FWHM) can be estimated." }
q_GDCLINQZ_00
The element gadolinium is part of which periodic table group?
[ 0 ]
[ "Lanthanides", "Actinides", "Alkaline-earth metals", "Transition metals" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Gadolinium, element number 64, is located in the exact middle of the lanthanide series of rare-earth elements." }
q_GDCLINQZ_01
The paramagnetic properties of gadolinium that make it suitable for a contrast agent derive from its
[ 2 ]
[ "Odd number of protons", "Odd number of protons and neutrons together", "Unpaired inner shell electrons", "Paired electrons in bonding orbitals" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Although all elements with odd numbers of nucleons possess nuclear paramagnetism, (responsible for the NMR phenomenon), this is extremely weak except in the immediate vicinity of the nucleus. Because electrons have the same spin (½) but a much smaller size than protons, their gyromagnetic ratios are 657 times larger, giving them powerful magnetic moments. It is unpaired inner shell electrons that give gadolinium its paramagnetic properties." }
q_GDCLINQZ_02
In its 4f shell, gadolinium has
[ 1 ]
[ "4 unpaired electrons", "7 unpaired electrons", "4 paired and 3 unpaired electrons", "7 paired electrons" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "The 4f electron shell has seven available positions, each of which may potentially be occupied by a lone electron or an electron pair. According to Hund’s rule of maximum multiplicity, electrons will occupy each position singly before filling them in pairs. Gadolinium has seven electrons available to fill the 4f shell, and they are all unpaired." }
q_GDCLINQZ_03
How many of gadolinium’s unpaired 4f shell electrons participate in bonding/chelation when made into a contrast agent?
[ 0 ]
[ "0", "1", "4", "7" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "None of gadolinium’s 4f shell electrons are directly involved in bonding, thus retaining its powerful paramagnetic properties when formulated as a contrast agent." }
q_GDCLINQZ_04
If gadolinium is chelated with a very large molecule (like albumin), what happens to its T1 relaxation time?
[ 1 ]
[ "It remains unchanged", "It shortens", "It lengthens", "It becomes shorter than T2" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Smaller aqueous contrast agents (like Gd-DTPA) tumble too quickly to be highly efficient at T1 relaxation. If the contrast agent attaches to a very large molecule (such as albumin), its motion slows to a range much closer to the Larmor frequency and its T1 relaxation time shortens dramatically. Note that choice (d) is impossible, as T1 is always greater than or equal to T2." }
q_GDCLINQZ_05
Which of the following statements about inner sphere and outer sphere relaxation effects is false?
[ 3 ]
[ "On a molecule-by-molecule basis, inner sphere relaxation is much more powerful than outer sphere relaxation.", "Inner sphere relaxation requires very close approach of a water molecules to the gadolinium metallic center.", "Although weaker on a per molecule basis, outer sphere effects are important because they involve larger numbers of water molecules.", "Most gadolinium contrast agents have multiple coordination sites available for inner sphere relaxation to take place." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "A consequence of its electron structure is that the Gd+3 ion typically exhibits nine coordination sites for bonding and chemical interactions. In all MR contrast agents now commercially available, a ligand group occupies eight of these sites while the ninth is available for transient bonding by a solvent water molecule for an inner sphere effect to occur. So choice (d) is false." }
q_GDCLINQZ_06
The T1- and T2-relaxivities of a contrast agent are given in what units?
[ 0 ]
[ "L/mmol-s", "mmol/s", "L/mmol", "unitless" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "The relaxivity of an MR contrast agent reflects how the relaxation rates of a solution change as a function of concentration [C]. Since a contrast agent may affect the two relaxation rates (1/T1 and 1/T2) individually, there are two corresponding relaxivities, denoted r1 and r2. By definition, 1/ΔT1 = r1 [C] and 1/ΔT2 = r2 [C]. Since ΔT1 and ΔT2 are given in seconds and [C] is measured in millimoles per liter, r1 and r2 have units of L/mmol-s." }
q_GDCLINQZ_07
In which of the following scenarios would the T2-shortening effects of gadolinium not be expected to be seen?
[ 2 ]
[ "MR of the bladder", "MR arthography", "Late enhancement phase cardiac MRI", "MR venography" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "In routine MR imaging, the mild T2-shortening effects of low doses of gadolinium (which decrease signal intensity) are usually overwhelmed by the more dominant T1-shortening effects (which increase signal intensity) and are therefore not normally observed. When high concentrations of contrast are present, low-T2 effects may predominate. This is seen routinely in MRI of the urinary tract, occasionally in MR arthrograms and venograms (where high concentrations of gadolinium are injected directly into joints or vessels); and in the \"first pass\" of gadolinium contrast through the vascular system on dynamic contrast enhanced (DCE) studies or time-resolved MR angiography. It would not be seen in late phase imaging of the myocardium." }
q_GDCLINQZ_08
Concerning gadolinium enhancement as a function of field strength, which statement is true?
[ 2 ]
[ "All currently used contrast agents demonstrate a slight increase in T1-relaxivity with increasing field strength.", "Contrast agents with lower T1 relaxivities (r1) values produce stronger enhancement.", "The same dose of contrast will typically generate more enhancement at 1.5T than 0.5T.", "Lower doses of contrast agents are needed at low-field compared to high-field." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Only (c) is true. Because tissue T1 values increase while contrast agent relaxivities are about the same or decrease only slightly with increasing field strength, the net effect is an increase in relative contrast enhancement as field strength increases Link to Q&A discussion" }
q_GDCLINQZ_09
Why do magnetization-transfer preparation pulses increase the visibility of gadolinium enhancement?
[ 1 ]
[ "They do not. This is a myth.", "They suppress the signal from background tissues.", "They shorten tissue T1.", "They interfere with gadolinium-water inner sphere relaxation." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Because gadolinium (Gd) enhancement is caused by a water-Gd ion interaction (not macromolecular cross-relaxation), MT pulses suppress the signal from background tissues and render Gd-enhanced areas more conspicuous." }
q_GDCLINQZ_10
The first commercially marketed gadolinium-based MR contrast agent was
[ 1 ]
[ "Dotarem®", "Magnevist®", "MultiHance®", "Omniscan®" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Magnevist®, marketed by Berlex Imaging (and subsequently acquired by Bayer), first received FDA approval in 1988." }
q_GDCLINQZ_11
Which of the following agents is macrocyclic?
[ 0 ]
[ "Dotarem®", "Magnevist®", "MultiHance®", "Omniscan®" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Dotarem®, along with ProHance® and Gadavist®, are all macrocyclic. The others are linear in structure." }
q_GDCLINQZ_12
Concerning gadoxetic acid constrast (Eovist®/Primovist®), which statement is false?
[ 1 ]
[ "Transient dyspnea after injection occurs in about 10% of patients.", "At least 90% of the administered dose is taken up by hepatocytes.", "Elimination is by both biliary excretion and glomerular filtration.", "Hepatic uptake and enhancement is decreased when bilirubin levels are elevated." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Only about half of the administered dose is taken up by hepatocytes. The remainder behaves as other nonspecific extracelleular gadolinium contrast agents." }
q_GDCLINQZ_13
Although no longer in production, what was unique about the liver contrast agent Teslascan™ sold in the 1990s and early 2000s?
[ 0 ]
[ "It was based on manganese.", "It was based on iron.", "It was based on copper.", "It was based on magnesium." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "To date the only manganese-based contrast agent ever approved for worldwide sales and clinical use was mangafodipir trisodium (Mn-DPDP), marketed in the 1990's under the tradename Teslascan™. Due to low sales, poor clinical performance, and concerns over toxicity, Teslascan™ was withdrawn from the US market in 2003 and from the EU in 2010." }
q_GDCLINQZ_14
And speaking of MR contrast agents no longer in production, what was unique about Ablavar®?
[ 2 ]
[ "It was based on manganese.", "It was based on iron oxide.", "It attached to albumin and served as a blood pool agent.", "It was taken up by the reticuloendothelial system." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Withdrawn as a product in 2017 by its manufacturer due to poor sales, Ablavar® had been designed specifically for vascular imaging. The drug underwent reversible bonding to plasma proteins (principally albumin) when injected into the blood, allowing it to be confined intravascularly for several hours." }
q_GDCLINQZ_15
Concerning superparamagnetic iron oxides (SPIOs) and ultra-small superparamagnetic iron oxides (US-SPIOs), which statement is false?
[ 1 ]
[ "US-SPIOs may be injected intravascularly, intradermally, or subcutaneously.", "The larger SPIOs are especially useful for lymph node imaging.", "Their T1 and T2 relaxivities are 10-20 x greater than gadolinium contrast agents.", "Their accumulation in the liver, spleen, and bone marrow can be mistaken for hemochromatosis." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Option (b) is false. The largest of these SPIO nanoparticles (50-100 nm) undergo rapid uptake by the liver. Smaller US-SPIO particles (5-50 nm), remain in the circulation and are cleared by lymphatics, draining into lymph nodes where they are captured and retained by macrophages/histiocytes (and potentially other sinus-lining endothelial cells)." }
q_GDCLINQZ_16
Concerning ferumoxytol (Feraheme®/Rienso®) which statement is false?
[ 0 ]
[ "It is now sold and marketed worldwide as an MR contrast agent.", "It has a long intravascular half-life after intravenous injection, behaving as a blood pool agent.", "It reduces both T1 and T2 relaxation times of the tissues wherein it accumulates.", "It must be given diluted and by slow intravenous injection." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Although ferumoxytol was originally developed as an MR contrast agent, it was instead marketed and approved for intravenous treatment of iron-deficiency anemia associated with chronic renal disease. It has not yet received indications for use as an MR contrast agent. It’s use in this form is considered “off label”." }
q_GDCLINQZ_17
Concerning bowel contrast materials, a large volume, water-based solution like VoLumen® would be classified as what type of contrast agent?
[ 2 ]
[ "Positive", "Negative", "Biphasic", "Neutral" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Biphasic contrast agents are all water-based, appearing dark on T1-weighted and bright on T2-weighted images. Biphasic enteric contrast agents like VoLumen® contain nonabsorbable additives (resins, polyethylene glycol, mannitol, sorbitol, or other sugar alcohols) that help draw in and retain intraluminal water." }
q_GDCLINQZ_18
Concerning bowel contrast materials, a suspension of magnetite-based particles like GastroMARK® (ferumoxsil) would be classified as what type of contrast agent?
[ 1 ]
[ "Positive", "Negative", "Biphasic", "Neutral" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Negative contrast agents are designed to make the intraluminal contents dark, especially on T2-weighted images. GastroMARK® causes a remarkable drop in signal within the bowel lumen on both T1 and T2-weighted images. The darkening on T1-weighted images allows visualization of mucosal enhancement." }
q_GDSAFEQZ_00
Compared to non-ionic iodine-based contrast agents, the frequency of acute adverse reactions to gadolinium-based contrast agents is
[ 1 ]
[ "About the same", "Slightly less", "Slightly more", "Much more" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Compared to many other drugs gadolinium contrast agents possess a very low incidence (<2.5%) of acute adverse reactions, mostly minor. Such rates are not too much higher than those occurring during placebo injection of saline and are about one-third as common as reaction rates recorded with nonionic iodine-based contrast media." }
q_GDSAFEQZ_01
Considering gadolinium-based contrast agents as a whole, what is the approximate rate of severe allergic reaction (e.g., facial edema, bronchospasm, hypotension, arrhythmias, widespread uticaria) expected?
[ 1 ]
[ "1 in 500 patients", "1 in 5000 patients", "1 in 50,000 patients", "1 in 500,000 patients" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Moderately severe hypersensitivity reactions (including bronchospasm, laryngospasm, facial edema, tachycardia, arrhythmias, or widespread urticaria) occur in about 1 in 5000 cases." }
q_GDSAFEQZ_02
Considering gadolinium-based contrast agents as a whole, what is the approximate risk of death from a severe allergic reaction?
[ 2 ]
[ "1 in 4,000 patients", "1 in 40,000 patients", "1 in 400,000 patients", "1 in 4,000,000 patients" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Worldwide, a number of severe anaphylactoid reactions to gadolinium-based MR contrast agents, including death, have been reported. The incidence of severe reactions is about 1 in 20,000 and the risk of death about 1 in 400,000." }
q_GDSAFEQZ_03
Which one of the following rare reactions to gadolinium has not been reported?
[ 0 ]
[ "Rhabdomyolysis", "Pancreatitis", "Encephalopathy", "Acute renal failure" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "To my knowledge, acute rhabdomyolysis has never occurred following gadolinium administration. The other three have been rarely reported." }
q_GDSAFEQZ_04
Comparing “true” anaphylaxis and “anaphylactoid” reactions to gadolinium contrast, which statement is correct?
[ 2 ]
[ "They can be distinguished based on their clinical presentation.", "Both are IgE-mediated.", "Both cause release of vasoactive amines and inflammatory mediators from mast cells.", "Both are dose-related." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "True anaphylaxis is an IgE-mediated type 1 hypersensitivity reaction and is not dose-related. Anaphylactoid reactions have an identical clinical pattern to \"true\" anaphylaxis but are not IgE-mediated. The two cannot be distinguished clinically. Both cause the same effect on basophils and mast cells to release histamine and other contents." }
q_GDSAFEQZ_05
Which of the following statements about the clinical features of nephrogenic systemic fibrosis (NSF) is incorrect?
[ 3 ]
[ "Nearly all reported cases have been in patients with severe renal disease or insufficiency.", "Skin thickening and joint contractures are characteristic.", "Involvement of the liver, lungs, muscles and heart also occurs.", "Although painful and disfiguring, the disease is seldom fatal." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Nephrogenic systemic fibrosis (NSF) is a rare, progressive, usually fatal disease characterized by skin thickening, painful joint contractures, and fibrosis of multiple organs including the lungs, liver, muscles, and heart. Nearly all documented cases have occurred in patients with chronic severe renal insufficiency who have received gadolinium contrast." }
q_GDSAFEQZ_06
Which one of the following gadolinium-based contrast agents is less likely than the others to be associated with NSF?
[ 1 ]
[ "Magnevist®", "Dotarem®", "OpitMARK™", "Omniscan™" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Except for the macrocyclic agent Dotarem®, the other three agents are all linear in structure and have been associated with the greatest number of reported cases of NSF. These have been classified by the ACR as Group I agents, and are no longer advertised in the US and have been withdrawn from the market in many other countries." }
q_GDSAFEQZ_07
Which gadolinium-based contrast agents has to date not been associated with any nonconfounded cases of NSF?
[ 3 ]
[ "Dotarem®", "ProHance®", "MultiHance®", "Eovist®" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "No cases of NSF have been reported with the newest gadolinium agent, Eovist® (gadoxetate). However, Eovist® is primarily intended for hepatic imaging and thus there is only limited worldwide experience with it compared to the more general purpose agents. Furthermore, Eovist® (and any future new contrast agents) are being given in an “NSF-conscious” era, where high doses of gadolinium are avoided and careful scrutiny of renal function is undertaken prior to contrast administration." }
q_GDSAFEQZ_08
Below what level of glomerular filtration rate (GFR) does the American Kidney Foundation consider Stage 3 (moderately reduced function) kidney disease?
[ 1 ]
[ "90 mL/min/1.73 m²", "60 mL/min/1.73 m²", "30 mL/min/1.73 m²", "15 mL/min/1.73 m²" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Stage 3 chronic kidney disease is generally diagnosed for GFRs in the range of 30-60 mL/min/1.73 m². This is about half the normal kidney function level of 90 mL/min/1.73 m²." }
q_GDSAFEQZ_09
Which one of the following statements about the use of gadolinium in neonates and infants is false?
[ 1 ]
[ "The half-life of gadolinium contrast in a normal newborn is at least 4 times longer than in an adult.", "The per kilogram dose of contrast should be lower than that in adults.", "Neonates have a lower renal excretion rate of gadolinium contrast than adults.", "No cases of NSF in neonates or infants have been reported." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Renal excretion rates aside, neonates have twice the volume of extracellular fluid than adults have in proportion to their body weights. Therefore, neonates and young infants who receive gadolinium contrast on a dose-per-kilogram basis will have blood gadolinium concentrations of only one-half that in adults after equilibration. This fact argues against using a lower dose per kilogram in infants than in adults, even though the serum half-life is prolonged. Clinical experience by our group and others has demonstrated that the adult dose of gadolinium contrast (0.1 mmol/kg for most extracellular agents) is also appropriate in infants and children." }
q_GDSAFEQZ_10
Concerning the administration of gadolinium contrast to lactating women, which statement is false?
[ 3 ]
[ "Peak excretion into breast milk occurs at about 50 minutes after injection.", "Only a tiny fraction (0.01%-0.04%) of the administered dose is excreted in breast milk.", "Only 1% of orally ingested contrast gadolinium contrast is absorbed by the infant.", "Current scientific evidence shows that breast feeding must be avoided for at least 24 hrs." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Because (b) and (c) are true, the dose entering the infant's circulation is extremely small (1/1,000,000 of the maternal dose) and the potential toxic effects are thought to be miniscule. Only out of an abundance of safety, many centers recommend (but do not require) suspending breast feeding for 24 hours after a gadolinium-enhanced MR study." }
q_GDSAFEQZ_11
Concerning the administration of gadolinium contrast during pregnancy, which statement is false?
[ 0 ]
[ "An increased number of congenital malformations have been observed in infants of mothers receiving gadolinium contrast during pregnancy.", "Gadolinium contrast easily passes through the placenta and into the fetal circulation.", "Gadolinium contrast absorbed by the fetus is excreted into the urine and subsequently into the amniotic fluid.", "Some gadolinium contrast in the amniotic fluid will be swallowed and resorbed through the fetal GI tract." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "In the only controlled human study to date of MRI and gadolinium exposure in pregnancy, a slightly higher incidence of stillbirths and early neonatal deaths (but not congenital malformations) was observed in the gadolinium-exposed group. More worrisome, however, was an increased number of rheumatologic, inflammatory, and infiltrative skin conditions, including some resembling nephrogenic systemic fibrosis (NSF)." }
q_GDSAFEQZ_12
Which of the following statements concerning gadolinium deposition in the brain is false?
[ 2 ]
[ "Accumulation occurs primarily in the basal ganglia, brainstem, and dentate nuclei.", "Several exposures are usually necessary before visible changes are seen.", "Changes are most visible on T2*-weighted images.", "The incidence of accumulation is less with macrocyclic contrast agents than linear ones." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "All are true except (b). High signal due to accumulated gadolinium is noted on T1-weighted images." }
q_GDSAFEQZ_13
Concerning “gadolinium deposition disease” which statement is false?
[ 1 ]
[ "The FDA has determined there is no convincing current evidence for this diagnosis.", "One important piece of clinical evidence for it is the increased incidence of Parkinson’s disease in patients receiving gadolinium contrast.", "No tissue injury or morphologic changes in gadolinium-accumulating brain areas can be detected by microscopy.", "Celebrity Chuck Norris withdrew his lawsuit against Bracco where he claimed they “poisoned” his wife with gadolinium." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "The incidence of Parkinson’s disease is not increased in patients who received gadolinium contrast." }
q_HEMQUIZ_00
How many iron atoms are in a hemoglobin molecule?
[ 3 ]
[ "1", "2", "3", "4" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Hemoglobin is comprised of four subunits, each containing a heme group with an iron (Fe) atom nestled at its center." }
q_HEMQUIZ_01
How many sites on each heme group are available for binding oxygen or another small molecule?
[ 0 ]
[ "1", "2", "3", "4" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "The Fe center of each heme group has 6 potential coordination sites, four of which are occupied by porphyrin nitrogens (N). The fifth coordination site (below the plane of the ring) covalently bonds with a histidine (His) residue from the F8 position of its respective globin chain. This leaves one free coordination site to which oxygen and other small molecules may transiently bind." }
q_HEMQUIZ_03
Which one of the hemoglobin derivatives listed below is diamagnetic?
[ 0 ]
[ "Oxyhemoglobin", "Deoxyhemoglobin", "Methemoglobin", "Ferritin" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 1, "hint": "Oxyhemoglobin has no unpaired electrons and is therefore diamagnetic." }
q_HEMQUIZ_04
In arterial blood from a healthy patient, what is the expected proportion of deoxyhemoglobin?
[ 1 ]
[ "0 %", "Less than 5%", "10 – 20 %", "Greater than 25 %" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "In arterial blood, the fraction of oxyhemoglobin is about 95%, while deoxyhemoglobin constitutes less than 5% (but not zero). A tiny amount of methemoglobin (<< 1%) may also be detected." }
q_HEMQUIZ_05
In venous blood from a healthy patient, what is the expected proportion of deoxyhemoglobin?
[ 3 ]
[ "0 %", "Less than 5%", "10 – 20 %", "Greater than 25 %" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "In venous blood, oxy-Hb still predominates, though in a smaller ratio (venous oxy:deoxy ≈ 70:30.)" }
q_HEMQUIZ_06
Which of the following effects on the MR signal does not result from local increased hematocrit during blood clotting?
[ 2 ]
[ "Decreased free water content, reducing T1, T2, and spin density.", "Decreased extracellular space, restricting diffusion.", "Increased concentration of phospholipids in red blood cell membranes, shortening T1.", "Increased concentration of hemoglobin, potentiating T2/T2* effects as transition to deoxy-hemoglobin occurs." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "All are true except (c). Phospholipid cell membranes have ultrashort T2 values and do not generate a fatty signal on MRI." }
q_HEMQUIZ_07
Which of the following imaging findings at 1.5T would not be expected to be seen in a hyperacute (< 12 hrs old) cerebral hematoma?
[ 2 ]
[ "Restricted diffusion", "T1 signal isointense to brain", "T2 signal moderately hypointense to brain", "At least a rim of hypointensity on GRE/SWI images" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "In a hyperacute hematoma, oxyhemoglobin still predominates, except perhaps at the periphery, and the imaging findings suggest a relatively high-water content lesion that is moderately hyperintense on T2-weighted images." }
q_HEMQUIZ_08
Which of the following imaging findings at 1.5T would not be expected to be seen in an acute (12–48 hrs old) cerebral hematoma?
[ 1 ]
[ "Restricted diffusion", "T1 signal hyperintense to brain", "T2 signal markedly hypointense to brain", "GRE/SWI images hypointense to brain" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "This phase of hematoma formation is dominated by intracellular deoxyhemoglobin, which shortens T2/T2* significantly. The hematoma becomes markedly hypointense on T2-weighted images." }
q_HEMQUIZ_09
Which of the following imaging findings at 1.5T would not be expected to be seen in an early subacute (2 days – 1 week old) cerebral hematoma?
[ 2 ]
[ "Restricted diffusion", "T1 signal hyperintense to brain", "T2 signal hyperintense to brain", "GRE/SWI images hypointense to brain" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "This is the phase of hematoma formation where intracellular methemoglobin predominates. This hemoglobin derivative is highly paramagnetic. Because it is still contained within red blood cells, T2/T2* shortening effects still occur, so T2 signal is low, not high. Access of water molecules close to the iron center due to a conformational change in the globin moiety result in T1 shortening and a bright T1 signal." }
q_HEMQUIZ_10
Which of the following imaging findings at 1.5T would not be expected to be seen in a late subacute (1 week – 2 months old) cerebral hematoma?
[ 1 ]
[ "Minimal to no restricted diffusion", "T1 signal hypointense to brain", "T2 signal hyperintense to brain", "GRE/SWI images show central hyperintensity" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "This phase of hematoma formation is dominated by extracellular methemoglobin, released from red blood cells that have ruptured. Methemoglobin is no longer concentrated into multiple intracellular compartments, but becomes uniformly dispersed throughout the hematoma cavity that is now bright on both T1- and T2-weighted images." }
q_HEMQUIZ_11
Which of the following imaging findings at 1.5T would not be expected to be seen in the center of a chronic (> 2 months old) cerebral hematoma?
[ 3 ]
[ "Minimal to no restricted diffusion", "T1 signal hypointense to brain", "T2 signal hyperintense to brain", "GRE/SWI central hypointensity to brain" ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "The imaging characteristics of the center of a chronic hematoma reflects its high water content. As such this region is typically hyperintense to brain on T2-weighted images and hypointense on T1-weighted images with no or minimally restricted diffusion. GRE/SWI signal centrally is also high, but may be dark along the rim of the hematoma cavity due to ferritin/hemosiderin deposition." }
q_HEMQUIZ_12
Which of the following statements about ferritin is incorrect?
[ 3 ]
[ "It is the principal iron storage molecule found in animal cells.", "It consists of a hollow protein shell into which iron atoms are packed.", "A typical ferritin molecule contains about 2000 iron atoms.", "It is ferromagnetic." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "The ferritin core acts as a solid piece of metal with a single magnetic domain, exhibiting superparamagnetism. Ferromagnetic materials, by contrast, consist of multiple erritinhemosiderin.html domains and retain some residual magnetization after an external magnetic field is removed." }
q_HEMQUIZ_13
Concerning ferritin and hemosiderin, which statement is true?
[ 0 ]
[ "The iron in hemosiderin is insoluble; the iron in ferritin is soluble.", "Both are visible by light microscopy.", "Ferritin is paramagnetic, but hemosiderin is ferromagnetic.", "Both hemosiderin and ferritin have a fixed structure and composition." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Only (a) is true. Ferritin is much smaller than hemosiderin and can only be visualized at electron microscopy. Both are paramagnetic. Ferritin has a fixed structure and composition; hemosiderin is an amorphous conglomeration of ferritin particles, proteins, and lipids." }
q_HEMQUIZ_14
Which of the following processes does not affect the appearance of subarachnoid hemorrhage (SAH) as compared to intraparenchymal brain hemorrhage?
[ 3 ]
[ "SAH clots are small.", "SAH clots are readily dispersed.", "SAH mixes with cerebrospinal fluid.", "Ambient oxygen levels in the subarachnoid space are low, resulting in faster aging of the hematoma." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Only (d) is false. Ambient oxygen levels in the subarachnoid space are high, resulting in slower aging of the hematoma. For example, methemoglobin formation is rare until at least 1 week after ictus." }
q_HEMQUIZ_15
Concerning CT and MRI of subarachnoid hemorrhage (SAH), which statement is false?
[ 1 ]
[ "Acute SAH is better seen on CT than on MRI.", "The best MR sequence for identifying acute SAH is T1-FLAIR.", "Subacute SAH may be better seen on MRI than CT.", "Evidence for remote SAH is much better seen on MRI than CT." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 3, "hint": "Option (b) is false. The best sequences for identifying SAH on MRI are T2-FLAIR, GRE/SWI, and DWI." }
q_HEMQUIZ_16
Which of the following statements concerning the appearance of hemorrhage at very low fields (<0.15 T) is true?
[ 2 ]
[ "Intracellular deoxyhemoglobin is noticeably dark on T2-weighted images.", "Intracellular methemoglobin is noticeably dark on T2-weighted images.", "Extracellular methemoglobin is bright on T1-weighted images.", "The center of a hyperacute hematoma is dark on T1-weighted images." ]
{ "subject": "MR Contrast Agents and Blood Quiz", "level": 2, "hint": "Only (c) is true. Neither intracellular deoxy- and met-Hb are dark on T2 weighted images as they are at high fields. This is because the dephasing is due to susceptibility which scales with the square of the magnetic field. The center of an acute clot is bright on T1-weighted images due to hemoconcentration and protein effect." }
q_GRADSAFE_00
How many sets of gradient coils does the typical MRI scanner use?
[ 2 ]
[ "1", "2", "3", "4" ]
{ "subject": "MR Safety and Screening Quiz", "level": 1, "hint": "The typical MR scanner uses 3 sets of paired gradient coils, one set for each of the x-, y-, and z-directions Link to Q&A discussion" }
q_GRADSAFE_01
The magnetic field strength of imaging gradients
[ 0 ]
[ "Is much less than that of the main field (Bo)", "Is slightly less than that of the main field (Bo)", "Is the same as that of the main field (Bo)", "Is slightly greater than that of the main field (Bo)" ]
{ "subject": "MR Safety and Screening Quiz", "level": 1, "hint": "The strength of the magnetic fields generated by gradients are less than 3% of the main magnetic field (Bo), so their static effects are of no concern. Rather, it is the time rate of change of these gradient fields (dB/dt) that poses potential safety issues for MR imaging." }
q_GRADSAFE_02
Which of the following physical effects is not the result of gradient activity?
[ 1 ]
[ "Acoustic noise", "Vertigo", "Peripheral nerve stimulation", "Metal implant heating" ]
{ "subject": "MR Safety and Screening Quiz", "level": 2, "hint": "Vertigo is primarily an effect due to subject movement in the static magnetic field (Bo). The other choices result from gradients." }
q_GRADSAFE_03
Concerning acoustic noise due to gradients, which statement is false?
[ 1 ]
[ "It is due to vibration of the gradient coils due to rapidly switched electrical currents.", "Acoustic noise in MRI may be temporarily uncomfortable, but it poses no real risk to hearing.", "Echo-planar sequences are especially loud.", "All patients and accompanying family members should be required to use ear protection." ]
{ "subject": "MR Safety and Screening Quiz", "level": 2, "hint": "Levels of acoustic noise in an MR scanner may reach 130 dB(A), producing both temporary and permanent threshold shifts (loss of hearing). Children are especially susceptible." }
q_GRADSAFE_04
Concerning gradient-related electromagnetic fields in patients, which statement is false?
[ 3 ]
[ "It is the coexistent electric field, rather than the gradient magnetic field, which causes peripheral nerve stimulation.", "Peak electric field values occur during the ramp up and ramp down periods of the gradients.", "Electric fields in a patient are concentrated superficially and at bone/fat/muscle junctions.", "The strongest gradient effects typically occur at magnet isocenter in the middle of the imaged field-of-view." ]
{ "subject": "MR Safety and Screening Quiz", "level": 2, "hint": "Answer d) is false. The centers of the paired gradient coils are located on either side of isocenter, and the strongest gradient effects typically occur toward the ends of the scanner and outside the imaged field-of-view." }
q_GRADSAFE_05
Concerning the strength-duration curve for nerve depolarization, which one of the following is true?
[ 0 ]
[ "The strength-duration curve plots the threshold for electrical stimulation as a function of stimulus strength and duration.", "The shape of the strength-duration curve is approximately linear.", "The rheobase is the minimum time required to stimulate a nerve regardless of stimulus strength.", "The chronaxie is the minimum voltage required to stimulate a nerve at any duration." ]
{ "subject": "MR Safety and Screening Quiz", "level": 3, "hint": "Only a) is true. The shape of the strength-duration curve is not linear, but has a hyperbolic/exponential shape. The rheobase represents the minimum stimulus required for excitation, while the chronaxie is the required time for a depolarizing stimulus applied at twice the rheobase value." }