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MRI boards
| Question | Answer |
|---|---|
| The primary biological effect of radiofrequency fields is: A. Tissue heating B. Asphyxiation C. Hyperthermia D. None of the above | Tissue heating |
| The strength of the gradient over a specific distance is known as the: A. Slew rate B. Rise time C. Duty cycle D. Flux lines | Slew rate The strength of the gradient over a specific distance is known as the slew rate. |
| The gradient rise time is defined as the: | Time it takes for the gradient to reach its full amplitude -The gradient rise time is defined as the time it takes for the gradient to reach its full amplitude |
| Magnetic field inhomogeneity is expressed in: A. Watts per kilogram B. Gauss per centimeter C. Tesla per meter D. Parts per million | Parts per million Magnetic field inhomogeneity is expressed in parts per million (ppm) |
| Utilization of surface coils yields all of the following EXCEPT: A. Increased FOV capabilty B. Localized, smaller FOV capability C. Increased SNR D. Smaller slice thickness | Increased FOV capabilty |
| Current FDA limits on time varying magnetic fields are: A. 23T/sec B. 5G/cm C. 20G/cm D. Once the patient experiences peripheral nerve stimulation | Once the patient experiences peripheral nerve stimulation Current FDA guidance limits the Time Rate of Change of Magnetic Field (dB/dt) to levels which do not result in painful peripheral nerve stimulation |
| A coil that is not properly tuned to the correct magnetic field strength will result in: A. Patient injury B. FID artifacts C. Signal loss D. Improvements in resolution capabilities | Signal loss A coil that is not properly tuned to the correct magnetic field strength will result in signal loss. |
| Applying two gradients simultaneously during slice selection would: A. Produce an artifact B. Produce an oblique slice C. Produce partial volume averaging D. Result in an equipment fault | Produce an oblique slice Applying two gradients simultaneously during slice selection would produce an oblique slice. |
| The effects of time varying magnetic fields can include all of the following EXCEPT: A. Peripheral nerve stimulation B. Magnetophosphenes C. Acoustic damage and/or hearing loss D. Warmth and/or increase in body temperature | Warmth and/or increase in body temperature The effects of time varying magnetic fields can include peripheral nerve stimulation, acoustic damage/hearing loss, magnetophosphenes ("seeing stars"). |
| RF heating is more of a concern in ________ sequences. A. Gradient echo B. Inversion recovery C. Fast spin echo D. Time of flight | Fast spin echo RF heating is more of a concern in fast spin echo sequences due to the multiple echo train lengths, leading to potential increases in tissue heating. |
| RF (radiofrequency) energy is: A. Low energy non-ionizing radiation B. Low energy ionizing radiation C. High energy non-ionizing radiation D. High energy ionizing radiation | Low energy non-ionizing radiation RF (radiofrequency) energy is low energy non-ionizing radiation. |
| Multiple coil elements combined with multiple receiver channels make a: A. Surface coil B. Circularly polarized coil C. Quadrature coil D. Phased array coil | Phased array coil A phased array coil is comprised of multiple coil elements combined with multiple receiver channels. |
| The coil construction in an MR system, from the innermost aspect to the outer: | Radiofrequency coils, gradient coils, shim coils, main magnet |
| The strength of the gradient magnetic fields are measured in: A. Gauss per centimeter B. Tesla per echo C. Watts per kilogram D. Millitesla per meter E. A and D | A and D |
| The ______________ is the speed rate of ascent or descent of a gradient from zero to its maximum amplitude, either positive or negative A. Slew rate B. Rise time C. Duty cycle D. Fringe field | Slew rate The gradient slew rate is the speed rate of ascent or descent of a gradient from zero to its maximum amplitude, either positive or negative |
| If a coronal slice plane has been selected, the __________ is enabled to alter the magnetic field around the patient's body. A. X gradient B. Y gradient C. Z gradient D. Shim coils | Y gradient Y gradient encodes coronal slice orientation |
| A technique utilized to reduce the MRI scan time which requires the use of an array coil is: A. Parallel imaging B. 1/2 NEX C. Rectangular field of view D. Phase encoding reduction technique | Parallel imaging multi-element phased array coils which are capable of acquiring multiple channels of data in parallel. This 'parallel imaging' technique uses unique acquisition schemes that allow for accelerated imaging. |
| Which of the following sequences would be more at risk for the effects that time varying magnetic fields can cause? A. SE B. FSE C. GE D. EPI | EPI EPI (Echo Planar Imaging) sequences can have more of a detrimental effect on patients with regards to time varying magnetic fields. |
| Cables from RF coils and gating/trigger leads should be: | Braided and positioned straight in the bore |
| The orientation of the main magnetic field in a high field, superconducting, short bore magnet is: A. Vertical B. Cylindrical C. Horizontal D. Asymmetrical | Horizontal Right Hand Grip rule -- Current passes through electrically induced coil of wire |
| The ____________ is responsible for the knocking noise the system makes while the sequence is in progress. B. RF energy being transmitted C. Rapid change/switching of the magnetic field by the gradient coils | Rapid change/switching of the magnetic field by the gradient coils |
| If a sagittal slice plane has been selected, the __________ is enabled to alter the magnetic field around the patient's body. A. X gradient B. Y gradient C. Z gradient D. Shim coils | X gradient X gradient encodes sagittal slice orientation |
| Which of the following has been documented to cause muscle contractions, cardiac arrhythmias, mild cutaneous sensations and visual light flashes? A. Time varying magnetic fields (gradient) C. Oscillating magnetic fields (radiofrequency) | time varying magnetic fields (gradient) |
| The measurement of radiofrequency absorption is delineated as: A. Watts per pound B. dB/dT C. Volts per kilogram D. Watts per kilogram | Watts per kilogram |
| The duty cycle is defined as the: A. Time it takes for the gradient to reach its full amplitude B. Time it takes longitudinal magnetization to regrow C. Time between TI and initial RF pulse D. Time the gradients are on during a TR period | Time the gradients are on during a TR period The duty cycle is defined as the time the gradients are on during a TR period |
| The gradient slew rate is the: | Rate of speed of ascent or descent of a gradient from zero to its maximum amplitude The gradient slew rate is defined as the rate of speed of ascent or descent of a gradient from zero to its maximum amplitude |
| Which of the following's primary biological effect is tissue heating/deposition? A. Static magnetic fields B. Gravitational earth magnetic fields C. Time varying magnetic fields (gradient) D. Oscillating magnetic fields (radiofrequency) | Oscillating magnetic fields (radiofrequency)Horizontal |
| A 6 inch surface coil is able to receive signal: A. 6 inches deep into the patient B. 3 inches deep into the patient C. 2 inches deep into the patient D. 1 inch deep into the patient | 3 inches deep into the patient |
| If a transverse/axial slice plane has been selected, the __________ is enabled to alter the magnetic field around the patient's body. A. X gradient B. Y gradient C. Z gradient D. Shim coils | Z gradient Z gradient is utilized to acquire axial/transverse images on a patient lying supine/prone in the magnet. |
| When going from a linear coil to a quadrature coil: A. Available FOV is reduced B. Parallel imaging is eliminated C. SNR is decreased by 40% D. SNR is increased by 40% | SNR is increased by 40% When going from a linear coil to a quadrature coil, SNR is increased by 40%. |
| The pulse sequence that should be utilized the least in a patient with implanted metallic hardware is: | Gradient echo Gradient echo sequences lack a 180° RF pulse that aids in correcting local magnetic field inhomogeneities, found in metallic implants. |
| The primary biological effect of radiofrequency fields is ____________. | Tissue heating |
| : It is ___________ that every patient having an MRI be provided auditory protection in the form ______________. | Recommended; earplugs and/or headphones |
| : __________ are reconstructed from diffusion weighted images with multiple b-values, and corresponds to the spatially distributed diffusion coefficients of the target tissues. | ADC images |
| : _______________ is defined as the range or spectrum of frequencies (minimum to maximum processed frequency)of a pulse sequence acquired by an RF system. | Bandwidth |
| The ____________ is an integrated part of the magnet design that acts as its own transceiver coil, with large FOV capabilities, but lacking the high SNR of localized coils. | Body coil |
| _____________ prevents or reduces motion artifacts in an MR image caused by the beating heart or pulsating blood flow and enables the images to be acquired synchronized to movement. | Cardiac triggering |
| A technique used to suppress fluids, utilizing a long echo time coupled with a long Inversion time is known as __________. | FLAIR |
| __________ materials, such as iron, contain unpaired electrons, each with a small magnetic field of its own, that align readily with each other in response to an external magnetic field. | Ferromagnetic Ferromagnetic materials, such as iron, contain unpaired electrons, each with a small magnetic field of its own, that align readily with each other in response to an external magnetic field. |
| The angle to which the longitudinal magnetization is tipped into the transverse plane, following the initial RF excitation pulse, is known as ________. | Flip angle |
| The linear increased or decreased change in the magnetic field of a certain orientation is defined as a _________. | Gradient |
| _________ is the magnetic and thermal environment through which nuclei exchange energy in longitudinal (T1) relaxation. | Lattice |
| ________ is comprised of the components of the magnetization in the imaging object after excitation, sampled from the receiver coil signal and stored as a function of time during the data acquisition of an MR imaging sequence | Raw data |
| _________ gradient – magnetic field gradient applied during the moment when the echo is formed | Readout |
| MRA technique relying on flow related enhancement to distinguish between stationary spins and flowing spins: | Time of flight |
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taylosam3