MRI registry review questions (scan principles)
Calculate the pixel area for a fast spin echo sequence with the following parameters: FOV 36cm, TR 600, TE 10, 512 x 512 matrix, 4 NEX, 5 mm slice thickness, 3 ETL. A. 0.49 mm2 B. 0.70 mm2 C. 0.96 mm2 D. 1.40 mm2 E. 1.47 mm3
A. 0.49 mm2 360 ÷ 512 = 0.70 0.70 x 0.70 = 0.49mm2
Calculate the pixel area for the following sequence: TR 450, TE 12, FOV 18cm, 224 x 256 matrix, 4 NEX. A. 0.56 mm2 B. 0.70 mm2 C. 0.80 mm2 D. 1.50 mm2
A. 0.56 mm2 FOV/matrix x FOV/matrix = pixel area. 180/224 x 180/256 = 0.56 mm2
A T1 weighted image will have an echo time (TE) in the range of: A. 10 - 30 ms B. 80 - 120 ms C. 350 - 700 ms D. 2000 - 6000 ms
A. 10 - 30 ms
A proton density weighted image will have an echo time (TE) in the range of: A. 10 - 35 ms B. 80 - 120 ms C. 350 - 700 ms D. 2000 - 6000 ms
A. 10 - 35 ms
Assuming all other parameters are the same, an echo time of ___________ ms provides the best Signal-to-Noise Ratio. A. 15 B. 30 C. 80 D. 110
A. 15
Which of the following echo train lengths generate a set of images with the greatest signal-to-noise, assuming all other parameters are the same? A. 3 ETL B. 6 ETL C. 12 ETL D. 16 ETL
A. 3 ETL
Which of the following parameter combinations would yield the most T1 weighting? A. 350 TR, 15 TE B. 500 TR, 25 TE C. 1600 TR, 30 TE D. 3500 TR, 120 TE
A. 350 TR, 15 TE
The substances that bind to gadolinium ions are defined as: A. Chelates B. Relaxivities C. Pathogens D. Echo trains
A. Chelates Because of its paramagnetic properties, solutions of chelated gadolinium complexes are used as intravenously administered gadolinium-based MRI contrast agents in MRI.
Increasing the field of view (FOV) would have what effect? A. Decrease spatial resolution B. Increase spatial resolution C. Decrease temporal resolution D. Increase temporal resolution
A. Decrease spatial resolution Increasing the field of view (FOV) would yield a decrease in spatial resolution(detail) in the image due to an increase in pixel size.
CSF suppression is performed with which type of technique? A. FLAIR B. STIR C. FISP D. SPGR
A. FLAIR
____________ is used as an anti-peristalsis agent in MR Enterography procedures. A. Glucagon B. Barium C. Gadolinium D. Immodium
A. Glucagon
As the TR is increased, I. SNR is increased II. Available number of slices is increased III. T2 information is maximized A. I and II B. I, II and III C. I and III D. None of the above
A. I and II As the TR increases, the SNR increases as well as the available number of slices.
As the TR is increased, I. SNR is increased II. Available number of slices is increased III. T2 information is maximized A. I and II only B. I and III only C. I only D. II only E. I, II and III
A. I and II only As the TR is increased, SNR is increased and the available number of slices is increased.
Increasing NSA will: A. Improve SNR B. Degrade SNR C. Shorten scan time D. Have no effect on SNR
A. Improve SNR
Decreasing the receiver bandwidth (utilizing a narrow BW): A. Increases susceptibility artifact B. Decreases susceptibility artifact C. Does not affect susceptibility artifact D. Decreases SNR E. A and D only F. B and D only
A. Increases susceptibility artifact
The time during which the frequency encoding gradient is on: A. Increases with a reduction in receiver bandwidth B. Decreases with a reduction in receiver bandwidth C. Is not affected by a reduction in receiver bandwidth D. Is limited by the inverse of the gradient slew rate
A. Increases with a reduction in receiver bandwidth
A pulse sequence that begins with a 180° RF pulse, followed by a 90° RF excitation pulse, would be a(n): A. Inversion recovery B. Spin echo C. Gradient echo D. Dual echo spin echo
A. Inversion recovery
What is the percentage of patients reported to have allergic reactions to gadolinium contrast agents? A. Less than 1% B. 10% C. 25% D. 50%
A. Less than 1%
Gadolinium is an example of a ___________ contrast agent. A. Paramagnetic B. Diamagnetic C. Ferromagnetic D. Quasimagnetic
A. Paramagnetic
Gadolinium is an example of a ___________ contrast agent. A. Paramagnetic B. Diamagnetic C. Super Paramagnetic Iron Oxide D. Ferromagnetic
A. Paramagnetic Gadolinium is an example of a paramagnetic contrast agent.
Each line of k-space is defined by the: A. Phase encoding gradient B. Frequency encoding gradient C. Slice select gradient D. Dictionary
A. Phase encoding gradient
A ______________ is defined as a picture element and has _________ characteristics. A. Pixel, two-dimensional B. Pixel, three-dimensional C. Voxel, two-dimensional D. Voxel, three-dimensional
A. Pixel, two-dimensional
A technique that reduces scan time by not filling as many lines of k-space in the phase direction, while maintaining spatial resolution, is known as: A. Rectangular FOV B. Parallel imaging C. Partial saturation D. Dual inversion recovery
A. Rectangular FOV
The range of transmitted frequencies at each slice position must _____ to maintain slice thickness. A. Remain constant B. Increase with each slice C. Decrease with each slice D. Disable, then re-enable
A. Remain constant
A fast spin echo sequence is faster than a conventional spin echo pulse sequence because: A. Several echoes for each slice are collected during each TR period B. T2* contrast takes less time C. A shorter TR is used for fast spin echo D. A smaller pixel size is utilized
A. Several echoes for each slice are collected during each TR period Scan time is reduced by a factor matching the number of echo train lengths, utilized in the fast spin echo pulse sequence
To produce an image based on differences in T1, the time interval between 90° excitation pulses should be: A. Short B. Long C. Inverted D. Refocused with steady state
A. Short A short TR (time between excitation pulses) is necessary to produce an image based on differences in T1.
In MRI, the function of gadolinium is to: A. Shorten the T1 and T2 times of tissues B. Lengthen the T1 and T2 times of tissues C. Lenghten the T2 time of tissue only D. Null both the T1 and T2 times of tissues
A. Shorten the T1 and T2 times of tissues
Which of the following statements is TRUE regarding spin echo sequences? A. T1 contrast is maximized with short TR's B. PD contrast is maximized with multiple echo train lengths C. T2 contrast is maximized with short TE's D. None of the above
A. T1 contrast is maximized with short TR's The shorter the TR (within range 350-700ms), the more T1 contrast
Water is dark and fat is bright in: A. T1 weighted images B. T2 weighted images C. STIR D. T2* gradient echo
A. T1 weighted images
What determines the amount of T1 weighting in an image? A. TR B. TE C. Flip Angle D. Matrix
A. TR
Metastatic lesions enhance after injecting a gadolinium chelate because of: A. The breakdown in the blood brain barrier B. T2 shortening C. The tangling of arteries and veins in metastatic disease D. None of the above
A. The breakdown in the blood brain barrier
Gradient echo sequences use flip angles: A. To control saturation effects B. After the 180º pulse C. Between the 90º and the 180º pulses D. To control SAR in bariatric patients
A. To control saturation effects
Reducing the number of lines filled in k-space will produce an image: A. With a decrease in spatial resolution B. With an increase in spatial resolution C. With an decrease in overall SNR D. A and C
A. With a decrease in spatial resolution
A sequence with a _________ TR and a _________ TE will exhibit T1 weighting. A. short; short B. short; long C. long; short D. long; long
A. short; short
Fat has a _______ T1 relaxation time and a ________ T2 relaxation time. A. short; short B. short; long C. long; short D. long; long
A. short; short
The standard dose for the adminstration of IV gadolinium chelates is: A. 1 mmol/kg B. 0.1 mmol/kg C. 0.2 mmol/kg D. 0.1 mmol/lb
B. 0.1 mmol/kg The standard dose for the adminstration of IV gadolinium chelates is 0.1 mmol/kg
Calculate the pixel area for a fast spin echo sequence with the following parameters: FOV 20cm, TR 3000, TE 120, 224 x 256 matrix, 3 NEX, 5 mm slice thickness, 12 ETL. A. 0.56 mm2 B. 0.69 mm2 C. 1.67 mm2 D. 3.45 mm2
B. 0.69 mm2 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Multiply phase pixel size x frequency pixel size = Pixel area (answer squared) Convert 20cm to 200 mm before calculating. 200 ÷ 224 = 0.89mm (phase dimension) 200 ÷ 256 = 0.78mm (frequency dimension) 0.89mm x 0.78mm = 0.69mm2
Calculate the pixel area for the following sequence: TR 4000, TE 120, FOV 28cm, 304 x 304 matrix, 2 NEX, ETL 12. A. 0.76 mm2 B. 0.85 mm2 C. 0.92 mm2 D. 1.84 mm2
B. 0.85 mm2
Calculate the pixel area for a fast spin echo sequence with the following parameters: FOV 30cm, TR 600, TE 10, 320 x 320 matrix, 4 NEX, 3 mm slice thickness, 3 ETL. A. 0.56 mm2 B. 0.88 mm2 C. 1.88 mm2 D. 2.64 mm2
B. 0.88 mm2 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Multiply phase pixel size x frequency pixel size = Pixel area (answer squared2) Convert 30cm to 300 mm before calculating. 300 ÷ 320 = 0.94mm (phase dimension) 300 ÷ 320 = 0.94mm (frequency dimension) 0.94 x 0.94 = 0.88 mm2
The pixel size of the images which result from a 3D acquisition using a 240mm FOV, a 272 x 272 matrix, 32 slices and a volume of 64 mm is: A. 0.56 x 0.56 mm B. 0.88 x 0.88 mm C. 1.12 x 1.12 mm D. 1.58 x 1.58 mm
B. 0.88 x 0.88 mm FOV ÷ Matrix = pixel size..... 240 ÷ 272 = 0.88mm
The smallest object that can be resolved in an image acquired with a 20cm FOV and a 224 x 224 matrix is _________ mm. A. 0.54 B. 0.89 C. 1.12 D. 1.89
B. 0.89
Calculate the pixel size for a fast spin echo sequence with the following parameters: FOV 20cm, TR 3000, TE 120, 224 x 256 matrix, 3 NEX, 5 mm slice thickness, 12 ETL. A. 0.089 mm x 0.078 mm B. 0.89 mm x 0.78 mm C. 0.98 mm x 0.87 mm D. 0.78 mm x 0.98 mm
B. 0.89 mm x 0.78 mm FOV ÷ Matrix = pixel size FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Convert 20cm to 200 mm before calculating. 200 ÷ 224 = 0.89mm (phase dimension) 200 ÷ 256 = 0.78mm (frequency dimension)
Choose the correct slice thickness to create an isotropic voxel for the following: TR 2000, TE 90, Matrix 256 x 256, FOV 32cm. A. 0.75 mm B. 1.25 mm C. 2.00 mm D. 2.50 mm
B. 1.25 mm
Calculate the voxel volume for the following pulse sequence parameters: TR 450, TE 20, FOV 24cm, 320 x 320 matrix, 3mm slice thickness. A. 0.75mm3 B. 1.69mm3 C. 1.75mm3 D. 2.25mm3
B. 1.69mm3 To calculate voxel volume, first determine pixel area. FOV/matrix x FOV/matrix = pixel area. Pixel area x slice thickness = voxel volume. 240/320 x 240/320 = 0.5625 mm2. 0.5625 x 3 = 1.69mm3
If the NEX is increased from 2 to 6, the signal-to-noise ratio increase would be: A. 1.4 B. 1.7 C. 2 D. 4
B. 1.7
If 24 4mm slices are planned with a gap of 1mm, the total anatomic coverage is _______ cm. A. 10 B. 12 C. 15 D. 120
B. 12 24 slices x 5mm (4 thickness + 1 gap) = 120 mm; ÷ 10 to calculate the coverage in cm.
Which RF pulse refocuses a decaying spin echo? A. 90° B. 180° C. 67° D. 30°
B. 180° The 180° RF pulse refocuses a decaying spin echo.
Which RF pulse is always absent in a gradient echo sequence? A. 90° excitation pulse B. 180° refocusing pulse C. Presaturation pulse D. Flip angle pulse
B. 180° refocusing pulse
Calculate the scan time for a spin echo sequence with the following parameters: TR 400, TE 25, 192 x 256 matrix, 2 NSA, 3mm slice thickness. A. 2 min 24 sec B. 2 min 34 sec C. 2 min 56 sec D. 3 min 6 sec E. 3 min 34 sec
B. 2 min 34 sec TR x Phase Matrix x NSA/NEX = Scan Time in a Spin Echo sequence, Divide by 1000 to convert ms (milliseconds) into seconds. 400 x 192 (phase matrix) x 2 ÷ 1000 = 153.6 seconds
Calculate the scan time for a fast spin echo sequence with the following parameters: FOV 16cm, TR 2500, TE 90, 208 x 256 matrix, 6 NEX, 5 mm slice thickness, 18 ETL. A. 2 min 24 sec B. 2 min 53 sec C. 2 min 56 sec D. 3 min 6 sec E. 3 min 34 sec
B. 2 min 53 sec Scan Time in a Fast Spin Echo Sequence : TR x Phase Matrix x NEX ÷ ETL, ÷ 1000 to convert to seconds. 2500 x 208 x 6 ÷ 18 ÷ 1000 = 173 seconds (2 min 53 sec)
The scan time of a fast spin echo sequence utilizing a TR of 3500ms, a TE of 90ms, a 256x256 matrix, 1NSA, a 220mm FOV and an echo train length of 5 is ______ minutes, approximately. A. 2 B. 3 C. 8 D. 11
B. 3 TR (3500) x Phase Matrix (256) x NSA (1) ÷ ETL (5) = 179200 ms, then divide by 1000 to get 179.2 seconds, or nearly 3 minutes.
Calculate the scan time for a 3D gradient echo sequence with the following parameters: FOV 20cm, TR 24, TE 10, 224 x 256 matrix, 1 NEX, 3.5 mm slice thickness, 40 slices. A. 3 min 25 sec B. 3 min 35 sec C. 3 min 38 sec D. 3 min 58 sec
B. 3 min 35 sec 3D sequence scan time : TR x Phase Matrix x NSA/NEX x # Slices = 3D Scan Time, ÷ 1000 to convert to seconds. 24 x 224 x 1 x 40 ÷ 1000 = 215 seconds (3 min 35sec)
In a fast spin echo sequence with a 28 cm FOV, 256 x 512 matrix, TR 2200, 90 TE, 5mm slice thickness, 8 ETL and 3 NEX, the scan time would be: A. 2 minutes 11 seconds B. 3 minutes 31 seconds C. 3 minutes 52 seconds D. 4 minutes 8 seconds
B. 3 minutes 31 seconds Scan time formula: TR x Phase Matrix x NEX ÷ ETL = total in milliseconds, then ÷ 1000 to achieve scan time in seconds. Be careful if you divide by 60 to achieve the scan time in decimal format (This example computes to 211 seconds, if you divide by 60 you get 3.52 seconds, which is 3 minutes 31 seconds, not 3 minutes 52 seconds)
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 3500, TE 100, 256 x 256 matrix, 4 NEX, 5 mm slice thickness, 14 ETL. A. 2 min 56 sec B. 4 min 16 sec C. 4 min 26 sec D. 4 min 27 sec E. 4 min 56 sec
B. 4 min 16 sec Scan Time in a Fast Spin Echo Sequence : TR x Phase Matrix x NEX ÷ ETL, ÷ 1000 to convert to seconds. 3500 x 256 x 4 ÷ 14 ÷ 1000 = 256 seconds (4 min 16 sec)
Which parameter will provide the better spatial resolution? A. 4mm slice thickness; 256 x 192 matrix B. 4mm slice thickness; 256 x 256 matrix C. 6mm slice thickness; 256 x 192 matrix D. 6mm slice thickness; 256 x 256 matrix
B. 4mm slice thickness; 256 x 256 matrix Thinner slices yield improved spatial resolution, in addition to smaller pixel size (higher matrix)
Calculate the scan time for a spin echo sequence with the following parameters: TR 450, TE 20, 224 x 256 matrix, 3 NSA, 4mm slice thickness. A. 1 min 16 sec B. 5 min 2 sec C. 5 min 4 sec D. 5 min 46 sec
B. 5 min 2 sec TR x Phase Matrix x NSA/NEX = Scan Time in a Spin Echo sequence, Divide by 1000 to convert ms (milliseconds) into seconds. 450 x 224 x 3 ÷ 1000 = 302 seconds.
A T2 weighted image will have an echo time (TE) in the range of: A. 25 - 40 ms B. 80 - 120 ms C. 1600 - 2200 ms D. 2000 - 6000 ms
B. 80 - 120 ms
Reducing the slice thickness will result in: A. An increase in partial volume averaging B. A decrease in SNR C. An increase in SNR D. A & B only E. None of the above
B. A decrease in SNR Reducing the slice thickness will result in a decrease in SNR, but will decrease partial volume averaging.
A set of specifically timed instructions to the magnet is known as: A. A recipe B. A pulse sequence C. Gyromagnetic instructor D. Fourier transformation
B. A pulse sequence A pulse sequence is a set of specifically timed instructions to the magnet telling it how images should look with regards to the tissue being sampled.
Structures that will always appear black on an MR image include all of the following EXCEPT: A. Air B. CSF C. Cortical bone D. Tendons/Ligaments E. Metal susceptibility artifacts
B. CSF
Decreasing the slice selection gradient strength will ________ of the resulting slice. A. Change the orientation B. Change the slice thickness C. Invert the phase and frequency sampling directions D. Alter the field of view
B. Change the slice thickness Decreasing the slice selection gradient strength will change the slice thickness of the resulting slice.
All of the following are types of inversion recovery sequences EXCEPT: A. STIR B. DWI C. FLAIR D. 3D-IR
B. DWI
As the number of phase encodings is increased from 256 to 512, SNR (signal to noise ratio): A. Increases B. Decreases C. Doubles D. Is unchanged
B. Decreases
As the TR increases the amount of T1 weighted contrast ___________. A. Increases B. Decreases C. Is nulled D. Is unchanged
B. Decreases As the TR increases the amount of T1 weighted contrast decreases.
If the receiver bandwidth (rBW) is decreased, the sampling rate: A. Increases B. Decreases C. Increases by the square root of 2 D. Does not change
B. Decreases The sampling rate is synonymous with the signal sampling frequency. According to the Nyquist theory, our sampling rate must be twice that of our sampling frequency in order to avoid aliasing in our image. Therefore, we sample twice per cycle. As the receiver bandwidth increases, so does the sampling rate or frequency. Therefore, the sampling rate is proportional to the receiver bandwidth. Increases in the receiver bandwidth results in increases in sampling rate.
Increasing the receiver bandwidth (rBW): A. Increases chemical shift artifacts B. Decreases chemical shift artifacts C. Decreases slice thickness D. Increases slice thickness
B. Decreases chemical shift artifacts Increasing the receiver bandwidth (rBW), or utilizing a wider BW, shortens the sampling time, which decreases chemical shift artifacts
Decreasing the receiver bandwidth (utilizing a narrow BW): A. Increases the number of slices available B. Decreases the number of slices available C. Does not change the number of slices available D. Decreases SNR E. A and D only F. B and D only
B. Decreases the number of slices available Decreasing the receiver bandwidth (utilizing a narrow BW) decreases the number of slices available (Decreasing the bandwidth increases the sampling time and lengthens the sequence timing, creating longer minimum TR and TE values)
SNR increases with all the following adjustments, EXCEPT: A. Increasing FOV B. Decreasing pixel size C. Increasing NEX/NSA D. Decreasing phase matrix
B. Decreasing pixel size Smaller pixel size (higher phase matrix) leads to improved resolution, but decreased SNR.
If the repetition time is doubled, the scan time will: A. Be 40% greater B. Double C. Be half of what it was D. Triple
B. Double TR is directly proportional to scan time (TR x Phase Matrix x NEX)
Two gradients applied at the same time during slice selection are utilized for: A. Reducing the cryogen boil off rate B. Encoding oblique slice planes C. Eliminating residual transverse magnetization for steady state D. Encoding 3D volumes for MRA
B. Encoding oblique slice planes The slice selection gradient is the determinant of scan plane, slice thickness; utilization of two gradients to perform this process allows for oblique slice orientation to be acquired.
Following the administration of IV gadolinium contrast, it is recommended to: A. Follow the injection with a flush of 0.5 mL saline B. Follow the injection with a flush of 5 mL saline C. Follow the injection with a flush of 100 mL saline D. Follow the injection with a flush of Volumen
B. Follow the injection with a flush of 5 mL saline
All of the following are true EXCEPT: A. Inversion recovery --- 180° RF followed by 90°RF B. Gradient echo --- 90° RF followed by 180° RF C. Fast spin echo --- 90° RF followed by train of 180° RF pulses D. Spin echo --- 90° RF followed by 180° RF
B. Gradient echo --- 90° RF followed by 180° RF Gradient echo lacks 180° RF pulses
What effect would decreasing the FOV have on the spatial resolution of an image? A. None B. Increase C. Decrease D. K space filled faster
B. Increase
All of the following yield a higher signal-to-noise ratio EXCEPT: A. Increase TR B. Increase TE C. Larger FOV D. Higher NEX E. Decrease Matrix
B. Increase TE An increase in TE will yield a decrease in SNR
A narrow receiver bandwidth: A. Decreases susceptibility artifact B. Increases susceptibility artifact C. Lowers SNR D. Should be used in the presence of metal implants
B. Increases susceptibility artifact
As the flip angle is increased, SNR(signal to noise ratio): A. Decreases until it reaches the Ernst angle B. Increases to a point called the Ernst angle C. Reduces to the Minimum Allowable Tesla (MAT) D. Is unaffected
B. Increases to a point called the Ernst angle As the flip angle is increased, SNR(signal to noise ratio) increases to a point called the Ernst angle.
How does Gadolinium function as a contrast agent? A. It is a direct image component, resonating at the same frequency as water B. It shortens the T1 time of tissue C. It lengthens the T2 time of tissues D. It emits radiofrequency that is picked up by the receiver coil
B. It shortens the T1 time of tissue
A Proton Density weighted image has a TR that is long to _____________, and a TE that is short to _____________. A. Maximize T1 contrast; minimize T2 contrast B. Minimize T1 contrast; minimize T2 contrast C. Maximize T1 contrast; maximize T2 contrast D. Minimize T1 contrast; maximize T2 contrast
B. Minimize T1 contrast; minimize T2 contrast
Fast spin echo sequences are fast because: A. The TE used is very short B. More than 1 line of k-space is acquired in each TR period C. No 180º refocusing pulses are used D. The excitation flip angle is very small
B. More than 1 line of k-space is acquired in each TR period Conventional spin echo techniques acquire one line of k-space during each repetition (TR). Fast spin echo techniques acquire multiple (2 to 50+) lines of k-space during each repetition.
Creating additional images in various planes from a 3D data set is accomplished by a technique known as: A. Maximum intensity projection (MIP) B. Multi-Planar reconstruction (MPR) C. Region of interest calculation(ROI) D. Subtraction
B. Multi-Planar reconstruction (MPR)
K-space is typically filled: A. With a funnel B. One line at a time C. From back to front D. From right to left
B. One line at a time
Another name for a picture element is a: A. Voxel B. Pixel C. Cubicle D. Filament
B. Pixel
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
B. Produce an oblique slice
_________ is a file on the computer where the collected echoes are stored prior to being processed into an image by the Fourier Transform. A. Analog to digital converter B. Raw data C. K-space D. A gradient
B. Raw data
A method of reducing MRI scan time by not filling as many lines of k-space in the phase direction, while maintaining spatial resolution, is known as: A. Halfscan B. Rectangular FOV C. Partial fourier D. Fast spin echo
B. Rectangular FOV
Enabling Driven Equilibrium will enable the operator to: A. Utilize additional acquisitions/packages B. Reduce TR and preserve contrast C. Suppress the signal from fat D. Eliminate wrap around (aliasing) artifacts
B. Reduce TR and preserve contrast
Gadolinium IV contrast: A. Lengthens the T1 and T2 times of tissues B. Shortens the T1 and T2 times of tissues C. Does not affect the T1 and/or T2 times of tissues D. Only shortens the T2 times of tissues
B. Shortens the T1 and T2 times of tissues
What effect would using a steep slice select slope and/or narrow bandwidth have on slice thickness? A. Partial volume averaging will occur B. Slices will be thin C. Slices will be thick D. Slices will cross-talk
B. Slices will be thin Steep slice select gradient slope yields thin slice thickness.
The FDA approved oral contrast agent for MRI makes bowel appear: A. T1 & T2 hyperintense B. T1 & T2 hypointense C. T1 hyperintense/ T2 hypointense D. T1 hypointense/ T2 hyperintense
B. T1 & T2 hypointense Perflubron, a type of perflorocarbon, has been used as a gastrointestinal MRI contrast agent for pediatric imaging, and works by reducing the amount of protons (as hydrogen) in a body cavity, thus causing it to appear dark in the images.
All of the following affect acquisition time EXCEPT: A. TR B. TE C. NEX D. Matrix
B. TE
What determines the amount of T2 weighting in an image? A. TR B. TE C. Flip Angle D. Matrix
B. TE
In an inversion recovery sequence, the time interval between the 180° RF pulse and the 90° RF pulse is the: A. TR B. TI C. TE D. 3T
B. TI The TI (inversion time) is the time interval between the 180° RF pulse and the 90° RF pulse.
All of the following are examples of INTRINSIC contrast parameters in tissues EXCEPT: A. ADC (apparent diffusion coefficient) B. TR C. T1 time D. T2 time E. Proton density
B. TR Intrinsic parameters in tissues are those that are specific to each tissue, inherent, and cannot be changed, such as ADC, T1/T2 time, specific proton density, and flow.
Which of the following is NOT affected by changing the slice thickness? A. The signal-to-noise ratio of the image B. The T1 contrast C. The image resolution D. The anatomical coverage
B. The T1 contrast
When gradient moment nulling is used as an imaging option in MR sequences: A. SNR is degraded B. The minimum TE is increased C. The minimum TE is decreased D. More slices are available per TR
B. The minimum TE is increased
As the number of excitations (NEX) is increased from 1 to 3, which of the following does NOT occur? A. The scan time triples B. The pixel size is increased C. The image resolution remains the same D. The signal-to-noise ratio is increased
B. The pixel size is increased
In a fast spin echo pulse sequence, if the TSE factor (echo train length) is increased by a factor of 3, the scan time will be: A. Twice as fast B. Three times faster C. Six times faster D. Nine times as fast
B. Three times faster In a fast spin echo pulse sequence, if the TSE factor (echo train length) is increased by a factor of 3, the scan time will be three times faster.
The echo time is the A. Time between the 180º inverting pulse and the 90º RF excitation pulse B. Time between the 90º RF pulse and the peak of the signal in the receiver coil C. Time it takes for the flip angle to reach the Ernst angle of peak signal D. Time between two 90º RF pulses
B. Time between the 90º RF pulse and the peak of the signal in the receiver coil
Tissues with _______ are bright on T1 weighted spin echo scans and tissues with _________ are bright on T2 weighted spin echo scans. A. short T1 times; short T2 times B. short T1 times; long T2 times C. long T1 times; short T2 times D. long T1 times; long T2 times
B. short T1 times; long T2 times
Calculate the pixel area for a fast spin echo sequence with the following parameters: FOV 28cm, TR 2000, TE 30, 256 x 320 matrix, 2 NEX, 4 mm slice thickness, 8 ETL. A. 0.56 mm2 B. 0.69 mm2 C. 0.96 mm2 D. 1.97 mm2 E. 3.84 mm2
C. 0.96 mm2 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Convert 28cm to 280 mm before calculating. 280 ÷ 256 = 1.09mm (phase dimension) 280 ÷ 320 = 0.88mm (frequency dimension) 1.09 x 0.88 = 0.96 mm2
Calculate the pixel size for a fast spin echo sequence with the following parameters: FOV 28cm, TR 2000, TE 30, 256 x 320 matrix, 2 NEX, 4 mm slice thickness, 8 ETL. A. 0.089 mm x 0.078 mm B. 1.89 mm x 0.78 mm C. 1.09 mm x 0.88 mm D. 1.78 mm x 0.98 mm
C. 1.09 mm x 0.88 mm FOV ÷ Matrix = pixel size FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Convert 28cm to 280 mm before calculating. 280 ÷ 256 = 1.09mm (phase dimension) 280 ÷ 320 = 0.88mm (frequency dimension)
A STIR sequence with a TI time of 160 ms will null signal from fat at what field strength? A. 0.5 Tesla B. 1 Tesla C. 1.5 Tesla D. 3 Tesla
C. 1.5 Tesla The T1 time of fat at 1.5 Tesla is approximately 240 with a null point of 160 ms.
In a spin echo sequence, the time between the 90° RF pulse and the 180° RF pulse is known as the: A. TR B. TE C. 1/2 TE D. TI E. Double Echo
C. 1/2 TE
If the radiologist requires 3mm slices axially acquired through the IAC, with a slice gap of 0.5mm, and requires 4.2cm total coverage, how many slices must be selected? A. 6 B. 9 C. 12 D. 15
C. 12 Anatomic slice coverage: Slice thickness + interslice gap x # of slices 4.2= x(3.5) 4.2/3.5= 1.2 1.2x10=12
Calculate the scan time for a fast spin echo sequence with the following parameters: FOV 20cm, TR 3000, TE 120, 224 x 256 matrix, 3 NEX, 5 mm slice thickness, 12 ETL. A. 2 min 8 sec B. 2 min 34 sec C. 2 min 48 sec D. 2 min 59 sec E. 3 min 4 sec
C. 2 min 48 sec Scan Time in a Fast Spin Echo Sequence : TR x Phase Matrix x NEX ÷ ETL, ÷ 1000 to convert to seconds. 3000 x 224 x 3 ÷ 12 ÷ 1000 = 168 seconds (2 min 48 sec)
Which set of scan parameters below would yield the best spatial resolution? A. 270 mm FOV, 192 x 512 matrix, 5mm slice thickness, 8 NEX B. 270 mm FOV, 256 x 512 matrix, 5mm slice thickness, 4 NEX C. 200 mm FOV, 512 x 512 matrix, 3mm slice thickness, 4 NEX D. 200 mm FOV, 512 x 512 matrix, 5mm slice thickness, 4 NEX
C. 200 mm FOV, 512 x 512 matrix, 3mm slice thickness, 4 NEX
If the maximum slices in a set TR is 10, and the necessary number of slices for a given sequence's anatomical coverage is 26, how many acquisitions (packages) will be required? A. 1 B. 2 C. 3 D. 4
C. 3 If the set TR allots 10 slices, 3 acquisitions will be required to obtain the entire 26 slice group. Raising the TR to allow for 14 slices would permit the slices to be acquired in two acquisitions, for example.
Calculate the scan time for a 3D gradient echo sequence with the following parameters: FOV 16cm, TR 25, TE 12, 208 x 256 matrix, 1 NEX, 4 mm slice thickness, 36 slices. A. 2 min 24 sec B. 2 min 53 sec C. 3 min 7 sec D. 3 min 12 sec E. 4 min 56 sec
C. 3 min 7 sec 3D sequence scan time : TR x Phase Matrix x NSA/NEX x # Slices = 3D Scan Time, ÷ 1000 to convert to seconds. 25 x 208 x 1 x 36 ÷ 1000 = 187 seconds (3 min 7 sec)
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 1800, TE 25, 208 x 224 matrix, 4 NEX, 3 mm slice thickness, 8 ETL. A. 2 min 24 sec B. 2 min 53 sec C. 3 min 7 sec D. 3 min 12 sec E. 3 min 20 sec
C. 3 min 7 sec Scan Time in a Fast Spin Echo Sequence : TR x Phase Matrix x NEX ÷ ETL, ÷ 1000 to convert to seconds. 1800 x 208 x 4 ÷ 8 ÷ 1000 = 187 seconds (3 min 7 sec)
What is the correct scan time for a spin echo sequence with the following parameters: TR 500 ms, TE 30 ms, matrix 208 x 208, 2 NEX, FOV 200mm? A. 2 minutes, 8 seconds B. 3 minutes 46 seconds C. 3 minutes 28 seconds D. 5 minutes 14 seconds
C. 3 minutes 28 seconds
A T1 weighted image will have a repetition time (TR) in the range of: A. 25 - 40 ms B. 80 - 120 ms C. 350 - 700 ms D. 2000 - 6000 ms
C. 350 - 700 ms
Which of the following combinations of flip angle (FA) and TR would produce a T2 weighted gradient echo? A. 45 TR; 30º flip angle B. 45 TR; 90º flip angle C. 450 TR; 30º flip angle D. 450 TR; 90º flip angle
C. 450 TR; 30º flip angle
Calculate the scan time for a 3D gradient echo sequence with the following parameters: FOV 16cm, TR 20, TE 9, 192 x 256 matrix, 2 NEX, 5 mm slice thickness, 40 slices. A. 4 min 6 sec B. 4 min 16 sec C. 5 min 7 sec D. 5 min 12 sec
C. 5 min 7 sec 3D sequence scan time : TR x Phase Matrix x NSA/NEX x # Slices = 3D Scan Time, ÷ 1000 to convert to seconds. 20 x 192 x 2 x 40 ÷ 1000 = 307 seconds (5 min 7sec)
In a spin echo pulse sequence, an echo is produced from: A. Flip angle B. A gradient C. A combination of two or more RF pulses D. A 90º RF pulse
C. A combination of two or more RF pulses
To obtain a thin slice thickness: A. A shallow gradient is applied with the transmit bandwidth at the Larmor frequency of H B. A shallow gradient is applied with the receiver bandwidth at the Larmor frequency of H C. A steep gradient is applied with the transmit bandwidth at the Larmor frequency of H D. A steep gradient is applied with the receiver bandwidth at the Larmor frequency of H
C. A steep gradient is applied with the transmit bandwidth at the Larmor frequency of H A steep gradient is applied with the transmit bandwidth at the Larmor frequency of H in order to achieve a thin slice thickness in MRI imaging.
Which of the following is NOT a result of reducing the FOV? A. Improved spatial resolution B. Decreased signal-to-noise C. Anatomical structures are displayed smaller in the image D. The pixel size becomes smaller
C. Anatomical structures are displayed smaller in the image Anatomical structures are displayed larger with a reduction in FOV.
IV Gadolinium contrast administration is indicated for: A. MRCP B. MRA of the renal arteries C. Central nervous system D. A & C only
C. Central nervous system
An isotropic voxel refers to a __________ shaped voxel. A. Circular B. Rectangular C. Cubic D. Oval
C. Cubic
A reduction in FOV will result in: A. Decrease in spatial resolution B. Increase in SNR C. Decrease in SNR D. None of the above E. A and C only
C. Decrease in SNR A reduction in FOV will result in a decrease in SNR, but will increase the spatial resolution in the image by lowering the pixel size.
An increase in TR will produce all of the following EXCEPT: A. Increase the signal-to-noise ratio B. Decrease T1 weighting C. Decrease the number of available slices D. Increase scan time
C. Decrease the number of available slices
Reducing the FOV (field of view) only will result in: A. Decreased spatial resolution B. Increased signal-to-noise C. Decreased signal-to-noise D. Increased T2 weighting
C. Decreased signal-to-noise
Reducing the TE: A. Increases the contrast based on T1 tissue relaxation times B. Reduces saturation effects C. Decreases the contrast based on T2 tissue relaxation times D. Increases fat suppression E. Increases signal from fluids
C. Decreases the contrast based on T2 tissue relaxation times
For a given number of slices, which of the following pulse sequences uses the most 180° RF pulses during each TR period? A. Spin echo B. Gradient echo C. Dual contrast spin echo D. Inversion recovery
C. Dual contrast spin echo
The fastest sequence commonly and currently available is: A. Fast spin echo B. Inversion recovery C. Echo planar imaging D. Gradient echo
C. Echo planar imaging Echo-planar imaging is a very fast magnetic resonance (MR) imaging technique capable of acquiring an entire MR image in only a fraction of a second
The central lines of k-space are associated with _____________ in a fast spin echo sequence. A. The echo train length B. Echo time C. Spatial resolution D. Contrast information
D. Contrast information
Increasing the TE in a spin echo pulse sequence: A. Has no effect on image contrast B. Enables more T1 information in the image C. Enables more T2 information in the image D. Decreases the T2 information in the image
C. Enables more T2 information in the image Increasing the TE in a spin echo pulse sequence enables more T2 information in the image.
The signal produced immediately following an RF pulse is: A. Ham radio signal B. Gradient echo C. FID D. MIP
C. FID
What formula is used to calculate the size of the pixel? A. Matrix ÷ FOV B. FOV ÷ slice thickness C. FOV ÷ matrix D. Slice thickness ÷ matrix
C. FOV ÷ matrix
The readout gradient is usually turned on during the sampling or readout of the peak echo and also during which other process? A. Slice selection B. Phase encoding C. Frequency encoding D. None of the above
C. Frequency encoding
The gradient that is on during the production of the echo is the: A. Slice select gradient B. Phase encoding gradient C. Frequency encoding gradient D. Inversion recovery gradient
C. Frequency encoding gradient The gradient that is on during the production of the echo is the frequency encoding (readout) gradient.
The most common positive contrast agent used in clinical MR imaging is: A. Barium B. Blueberry juice C. Gadolinium D. Ionic contrast
C. Gadolinium
All of the following are true regarding gadolinium EXCEPT: A. Gadolinium chelates do not pass normal blood-brain barrier B. Gadolinium is not FDA approved for whole body MRA C. Gadolinium has six unpaired electrons D. Gadolinium chelates do pass a disrupted blood-brain barrier
C. Gadolinium has six unpaired electrons
In which of the following pulse sequences would you expect to find the shortest TR? A. Fast spin echo B. Inversion recovery C. Gradient echo D. Spin echo
C. Gradient echo
In a dual contrast spin echo sequence with echo times of 25ms and 90ms, the second echo image has __________ than the first echo image I. more T2 contrast II. lower signal-to-noise ratio III. more T1 contrast A. I only B. III only C. I & II only D. I & III only
C. I & II only Longer TE's provide more T2 contrast, but reduced signal-to-noise ratios
Gradient moment nulling is used to compensate for: I. First order motion II. Second order motion III. Slow flowing vessels IV. Fast flowing vessels A. I and II B. I, II and III C. I and III D. I and IV E. I, II, III and IV
C. I and III
The timing of the RF pulses in an MRI pulse sequence controls: A. How long the procedure takes B. Pixel size C. Image contrast D. Spatial resolution
C. Image contrast
Lengthening TR with a short TE in a spin echo sequence will: A. Increase T2 weighting B. Increase T1 weighting C. Increase proton density weighting D. Increase inversion time to null signal from fat
C. Increase proton density weighting
Decreasing the receiver bandwidth (narrow rBW): A. Increases the contrast based on T1 tissue relaxation times B. Decreases the SNR of the image C. Increases the SNR of the image D. Inverts the SNR of the image E. Does not affect the SNR of the image
C. Increases the SNR of the image
A sequence with a _________ TR and a _________ TE will exhibit PD weighting. A. Short; short B. Short; long C. Long; short D. Long; long
C. Long; short
VoLumen would be selected for which MR procedure? A. MRCP B. MR perfusion C. MR enterography D. MRA abdomen E. MRA intracranial circulation
C. MR enterography
All of the following are true mechanisms of saturation EXCEPT: A. A saturation pulse excites hydrogen protons to a frequency that gives no signal on the image B. Partial saturation yields T1 weighting; occurs when NMV >90° C. Partial saturation yields T1 weighting; occurs when NMV is 180° D. Full saturation suppresses longitudinal magnetization; occurs when NMV is 180
C. Partial saturation yields T1 weighting; occurs when NMV is 180°
With a recFOV that is twice as tall as it is wide, and the phase direction oriented along the smaller "width" dimension of the FOV, which of the following relationships between the frequency and phase steps yields square pixels? A. Frequency steps must be half the phase encoding steps B. Phase steps must equal the number of frequency steps C. Phase steps must be half the number of frequency steps D. The pixels will always be rectangular
C. Phase steps must be half the number of frequency steps With a 50% Rectangular FOV, the phase matrix (rectFOV direction) must be exactly half the frequency matrix in order to yield square pixels.
Presaturation pulses typically occur: A. Prior to the TE B. At the time 1/2 TE C. Prior to the excitation pulse D. Between the 90° RF pulse and the 180° pulse
C. Prior to the excitation pulse
The maximum intensity projection algorithm: A. Separates the k-space phase and frequency modulations into images B. Subtracts a mask from a contrast image, leaving only blood vessels C. Projects the high intensity pixels which represent blood vessels/ducts into one image D. Calculates the frequencies required for 90° and 180° RF pulses
C. Projects the high intensity pixels which represent blood vessels/ducts into one image
All of the following would aid in reducing scan time EXCEPT: A. Utilizing the coarsest matrix possible B. Reducing NEX C. Reducing TE D. Increasing parallel imaging factor E. Setting TR to shortest
C. Reducing TE
Which of the following would NOT compensate for the change in signal-to-noise as a result of decreasing the FOV? A. Reducing the image matrix B. Reducing the number of echo train lengths C. Reducing the number of excitations D. Increasing slice thickness
C. Reducing the number of excitations
Which factors affect the flip angle? A. Gradient slew rate and the magnetic field strength B. Duty cycle and RF field C. Strength and duration of the RF field D. Static magnetic field and gradient rise time
C. Strength and duration of the RF field
Water is hyperintense and fat is typically dark in: A. T1 weighted images B. Proton density weighted images C. T2 weighted images D. FLAIR
C. T2 weighted images
What is wrong with a T2 weighted, fast spin echo image that has a 1.1 second TR and an 90 millisecond TE? A. The ETL will degrade the image resolution B. The TE will yield insufficient T2 weighted contrast C. The TR does not sufficiently minimize the T1 weighted contrast D. All of the above
C. The TR does not sufficiently minimize the T1 weighted contrast
With regards to k-space, the data containing signal and contrast information are located along: A. X gradient B. The phase axis C. The central lines D. The outer lines
C. The central lines
All of the following are properties of T1 weighting EXCEPT: A. Short TR, short TE are the parameter requirements B. Spin lattice C. Transverse magnetization D. Timed at 63% recovery E. Contrast is controlled by TR
C. Transverse magnetization
What specifically is a SPGR sequence spoiling? A. The hippocampus B. Longitudinal magnetization C. Transverse magnetization D. Gradient amplitude
C. Transverse magnetization SPoiled Gradient Recalled echo -- The RF excitation pulse is phase shifted each time the RF is applied which prevents accumulation of the residual transverse magnetization effects throughout the acquisition.
Calculate the pixel size for a fast spin echo sequence with the following parameters: FOV 30cm, TR 600, TE 10, 320 x 320 matrix, 4 NEX, 3 mm slice thickness, 3 ETL. A. 0.089 mm x 0.078 mm B. 0.89 mm x 0.78 mm C. 0.94 mm x 0.87 mm D. 0.94 mm x 0.94 mm
D. 0.94 mm x 0.94 mm
Which of the following echo train lengths generates images in the shortest amount of time? A. 3 ETL B. 6 ETL C. 12 ETL D. 16 ETL
D. 16 ETL
A proton density weighted image will have a repetition time (TR) in the range of: A. 25 - 40 ms B. 80 - 120 ms C. 350 - 700 ms D. 1600 - 4000 ms
D. 1600 - 4000 ms
Calculate the dose of contrast (0.1mmol/kg) that should be administered to a patient weighing 176 lbs with normal kidney function in a routine MR examination. A. 7mL B. 9mL C. 13mL D. 16mL E. 18mL
D. 16mL Divide 176 lbs by 2.2 (lbs per kg), then multiply the kg (80) by 0.2 ml/kg = 16mL
Calculate the scan time for a spin echo sequence with the following parameters: TR 400, TE 24, 208 x 256 matrix, 2 NSA, Flip angle 90, 3.5 mm slice thickness. A. 1 min 56 sec B. 2 min 7 sec C. 2 min 36 sec D. 2 min 46 sec E. 3 min 4 sec
D. 2 min 46 sec TR x Phase Matrix x NSA/NEX = Scan Time in a Spin Echo sequence, Divide by 1000 to convert ms (milliseconds) into seconds. 400 x 208 x 2 ÷ 1000 = 166 seconds.
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 3000, TE 100, 512 x 512 matrix, 2 NEX, 5 mm slice thickness, 18 ETL. A. 1 min 46 sec B. 1 min 59 sec C. 2 min 36 sec D. 2 min 51 sec E. 3 min 34 sec
D. 2 min 51 sec 3000 x 512 x 2 ÷ 18 ÷ 1000 = 171 seconds
Calculate the scan time for a spin echo sequence with the following parameters: TR 350, TE 10, 256 x 256 matrix, 2 NEX, 5 mm slice thickness. A. 1 min 46 sec B. 1 min 59 sec C. 2 min 56 sec D. 2 min 59 sec E. 3 min 4 sec
D. 2 min 59 sec TR x Phase Matrix x NSA/NEX = Scan Time in a Spin Echo sequence, Divide by 1000 to convert ms (milliseconds) into seconds. 350 x 256 x 2 ÷ 1000 = 179 seconds
Calculate the voxel volume for a fast spin echo sequence with the following parameters: FOV 30cm, TR 600, TE 10, 320 x 320 matrix, 4 NEX, 3 mm slice thickness, 3 ETL A. 0.76 mm2 B. 0.88 mm2 C. 1.88 mm3 D. 2.64 mm3 E. 3.84 mm3
D. 2.64 mm3 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Multiply phase pixel size x frequency pixel size = Pixel area (answer squared2) Pixel area x slice thickness = Voxel volume (answer cubic3) Convert 30cm to 300 mm before calculating. 300 ÷ 320 = 0.94mm (phase dimension) 300 ÷ 320 = 0.94mm (frequency dimension) 0.94 x 0.94 = 0.88 mm2 (pixel area) 0.88 x 3mm (thickness) = 2.64mm3
A T2 weighted image will have a repetition time (TR) in the range of: A. 25 - 40 ms B. 80 - 120 ms C. 350 - 700 ms D. 2000 - 6000 ms
D. 2000 - 6000 ms
To increase the voxel volume, which parameters would be adjusted? A. Slice thickness and interslice gap B. Matrix, slice thickness and slice gap C. FOV, slice gap and matrix D. FOV, slice thickness and matrix
D. FOV, slice thickness and matrix
Calculate the scan time for a fast spin echo sequence with the following parameters: TR 2000, TE 30, 192 x 224 matrix, 3 NEX, 4 mm slice thickness, 6 ETL. A. 1 min 9.2 sec B. 2 min 34 sec C. 3 min 2 sec D. 3 min 12 sec E. 3 min 20 sec
D. 3 min 12 sec Scan Time in a Fast Spin Echo Sequence : TR x Phase Matrix x NEX ÷ ETL, ÷ 1000 to convert to seconds. 2000 x 192 x 3 ÷ 6 ÷ 1000 = 192 seconds (3 min 12 sec)
Calculate the voxel volume for a fast spin echo sequence with the following parameters: FOV 20cm, TR 3000, TE 120, 224 x 256 matrix, 3 NEX, 5 mm slice thickness, 12 ETL. A. 0.56 mm3 B. 0.69 mm2 C. 1.88 mm2 D. 3.45 mm3 E. 5.69 mm3
D. 3.45 mm3 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Multiply phase pixel size x frequency pixel size = Pixel area (answer squared2) Pixel area x slice thickness = Voxel volume (answer cubic3)
Which of the following parameter combinations would yield the most T2 weighted image? A. 500 TR, 20 TE B. 1600 TR, 30 TE C. 2000 TR, 80 TE D. 3500 TR, 120 TE
D. 3500 TR, 120 TE
Calculate the voxel volume for the following pulse sequence: TR 2000, TE 85, FOV 28cm, Matrix 272 x 320, 5mm slice thickness, 3 NSA. A. 0.88 mm3 B. 1.03 mm3 C. 1.91mm3 D. 4.55 mm3
D. 4.55 mm3 To calculate voxel volume, first determine pixel area. FOV/matrix x FOV/matrix = pixel area. Pixel area x slice thickness = voxel volume. 280/272 x 280/320 = 0.91 mm2. 0.91 x 5 = 4.55mm3
Which of the following sets of parameters would show edema as hyperintense? A. 400 TR, 20 TE B. 1600 TR, 30 TE C. 3500 TR , 35 TE D. 4000 TR, 90 TE
D. 4000 TR, 90 TE T2 weighted sequences (long TR -- >2000 and long TE >80) will yield hyperintense(bright) signal from fluid (edema)
Calculate the scan time for a spin echo sequence with the following parameters: TR 500, TE 24, 224 x 256 matrix, 3 NEX, 4 mm slice thickness. A. 4 min 36 sec B. 5 min 2 sec C. 5 min 6 sec D. 5 min 36 sec
D. 5 min 36 sec
Which of the following pulse sequence parameter combinations would yield an image with the most blurring? A. 400TR, 25TE, 256 x 256, 5mm slice thickness, 1NSA B. 2000TR, 30TE, 256 x 256, 5mm slice thickness, 6 ETL, 2NSA C. 4000TR, 60TE, 256 x 256, 5mm slice thickness, 12 ETL, 4NSA D. 6000TR, 80TE, 256 x 256, 5mm slice thickness, 16 ETL, 4NSA
D. 6000TR, 80TE, 256 x 256, 5mm slice thickness, 16 ETL, 4NSA
Assuming all other parameters are the same, a ___________ ms TR provides the best signal-to-noise ratio. A. 30 B. 200 C. 500 D. 800
D. 800
What would the scan time be in a 3D volume acquisition as follows: TR 32 ms, TE 4 ms, Flip Angle 15°, FOV 18cm, 2mm slice thickness, 96 slices, 192 x 256 matrix, 1 NEX? A. 4 min 28 sec B. 5 min 12 sec C. 8 min 42 sec D. 9 min 50 sec
D. 9 min 50 sec (TR*phase matrix*NEX) * # of slices 32*192*1*96 = 589824 589824/1000= 589.824 589.824/60= 9.8304 .8304*60= 49.824 sec 9min & 50sec
Multiplanar reconstructions are typically utilized in 3D pulse sequences because: A. 2D slices are too thick to reformat B. 2D slice groups are too long C. There are gaps between 2D slices D. A & C only E. B & C only
D. A & C only The option to reconstruct multiple planes from a single data set is advantageous in a 3D pulse sequence due to the thin slices used in 3D sequences and the lack of interslice gap.
Acquiring a bit more than half the phase k-space samples, then interpolating the data with zeroes for the remaining half is a technique known as: A. Half Fourier B. Zero fill C. Fast spin echo D. A and/or B
D. A and/or B Acquiring a bit more than half the phase k-space samples, then interpolating the data with zeroes for the remaining half is a technique known as Half Fourier, or Zero Fill.
__________ is defined as a small change in the magnetic field along a particular axis. A. Analog to digital converter B. K-space C. Fourier transform D. A gradient
D. A gradient
Each train of echoes has what effect on the pulse sequence in a fast spin echo? A. Increases SAR absorption B. Reduces scan time C. Lowers SNR D. All of the above
D. All of the above
Slice ___________ is determined by the slice selection process. A. Position B. Orientation C. Thickness D. All of the above
D. All of the above
In an inversion recovery sequence, image contrast is controlled by: A. TR B. TE C. TI D. All of the above
D. All of the above In an inversion recovery sequence, image contrast is controlled by TR (repetition time), TE (echo time) and TI (inversion time)
Which of the following statements is FALSE regarding the use of a narrow receiver bandwidth? A. It generates lower signal-to-noise ratio images B. It should be applied in anatomical regions that contain high fat and water interfaces C. It is utilized with a high readout gradient amplitude D. All of the above
D. All of the above Lower bandwidth = higher signal-to-noise = more chemical shift
Reducing the phase matrix from 256 to 192 will: A. Increase the signal-to-noise ratio B. Decrease imaging time C. Decrease spatial resolution D. All of the above
D. All of the above Reducing the phase encoding matrix yields higher SNR, shorter scan times, but decreased spatial resolution due to the increased pixel size.
2D acquisitions usually require: A. Flow compensation B. Presaturation slabs C. Fat suppression D. An interslice gap
D. An interslice gap
T1 is useful for __________, whereas T2 is utilized for depicting __________. A. Blood; anatomy B. Anatomy; blood C. Pathology; anatomy D. Anatomy; pathology
D. Anatomy; pathology T1 is useful for anatomy, whereas T2 is utilized for depicting pathology(edema).
Decreasing the TR will: A. Lower SNR B. Reduce scan time C. Increase SNR D. Both A and B
D. Both A and B
VoLumen is a contrast agent used for: A. Vessel lumen relaxivity B. Volume rendering MRCP C. Blood brain barrier D. Bowel enhancement
D. Bowel enhancement
High amplitude signals are stored in the: A. Outer edges of k-space B. Bottom line of k-space C. Top line of k-space D. Center portion of k-space
D. Center portion of k-space
The Ernst angle can be defined as the optimal ___________ that yields the ____________ signal for a particular spin in the least amount of time. A. NSA; minimum B. TR; maximum C. Flip angle; minimum D. Flip angle; maximum
D. Flip angle; maximum
The process that digitizes the MR signals is known as: A. Hahn echos B. Faraday's law C. Gyromagnetic reconstruction D. Fourier transform
D. Fourier transform
When performing a gradient echo pulse sequence, what is used to refocus the protons and create the echo? A. A focus group B. Shim coils C. RF coils D. Gradient coils
D. Gradient coils In a gradient echo pulse sequence, the gradient coils are used to refocus the protons and create the echo.
As the TE is increased, I. The available number of slices is increased II. The available number of slices is decreased III. SNR increases IV. T1 contrast is maximized A. I and III only B. II and III only C. I only D. II only E. I, II, III and IV
D. II only
The timing of RF pulses in an MRI pulse sequence controls: A. Resolution capabilities B. Amount of signal in the image C. The time the coil receives the echo D. Image contrast
D. Image contrast
Decreasing rBW (receiver bandwidth)by a factor of two: A. Decreases SNR by 2 B. Increases SNR by 2 C. Decreases SNR by √2 D. Increases SNR by √2 E. Increases SNR by 4 F. Decreases SNR by 4
D. Increases SNR by √2
A sequence with a _________ TR and a _________ TE will exhibit T2 weighting. A. Short; short B. Short; long C. Long; short D. Long; long
D. Long; long
Complete saturation is a condition where: A. Spin density effects dominate contrast B. The signal from fluid is inverted from a long TI C. Transverse magnetization is not allowed to recover between excitations D. Longitudinal magnetization is not allowed to recover between excitations
D. Longitudinal magnetization is not allowed to recover between excitations
Conventional spin echo sequences begin with a __________ RF excitation pulse. A. 25° B. 45° C. 180° D. None of the above
D. None of the above Conventional spin echo sequences begin with a 90° RF excitation pulse.
_______ is when only half the views of k-space are filled in the frequency axis. A. Diffusion tensor B. Anti aliasing C. Half Fourier D. Partial or fractional echo
D. Partial or fractional echo Partial or fractional echo is when only half the views of k-space are filled in the frequency axis, an acceleration technique used to shorten TR and TE.
Chemical or spectral fat suppression techniques suppress fat signal based on the: A. Amount of fat being imaged B. Presence of T1 relaxation in the tissue C. Presence of T2 relaxation in the tissue D. Precessional frequency of fat
D. Precessional frequency of fat
The presaturation pulses typically are found: A. Between the 90º and the 180º pulses B. Prior to the TE C. Following the 180º pulse D. Prior to the excitation pulse E. A and D only
D. Prior to the excitation pulse
In order to generate an MR image, the slice select gradient must be turned on during: A. T1 relaxation B. Collection of the echo C. Patient positioning D. RF energy application
D. RF energy application
Presaturation pulses are often used to: A. Improve spatial resolution B. Improve temporal resolution C. Reduce scan time D. Reduce flow artifacts E. Enable bright signal from flowing blood
D. Reduce flow artifacts
In a gradient echo sequence, reducing the flip angle while maintaining the TR reduces: A. Scan time B. T2* contrast C. Inversion delay D. Saturation
D. Saturation
Which of the following sequences is the most insensitive to magnetic field inhomogeneity? A. RF spoiled gradient echo B. Steady state rephased gradient echo C. Echo planar D. Spin echo
D. Spin echo Spin echo sequences contain 180° RF refocusing pulse(s), which aid in correcting for local field inhomogeneities, therefore making them the most INSENSITIVE to inhomogeneity.
Which of the following statements is FALSE? A. T2 contrast is maximized with long TE's B. T1 contrast is maximized with short TR's C. Flip angle can control image contrast weighting D. T1 weighting is adjusted with short TE's
D. T1 weighting is adjusted with short TE's
If a sequence with a matrix of 256 x 512 is adjusted to 512 x 512, A. The SNR will stay the same B. The scan time will decrease C. The SNR will increase and the scan time will decrease D. The SNR will decrease and the scan time will increase
D. The SNR will decrease and the scan time will increase
With regards to k-space, the data containing high resolution are located along: A. The Z gradient B. The phase axis C. The central lines D. The outer lines
D. The outer lines
Following the injection of contrast, which of the following patients are most likely to have a potentially serious reaction? A. Anemic patients B. Those with a high BUN C. Hypertensive patients D. Those with asthma or allergic respiratory disorders E. Claustrophobic patients
D. Those with asthma or allergic respiratory disorders
The repetition time is the: A. Time between the 180º inverting pulse and the 90º RF excitation pulse B. Time between the 90º RF pulse and the peak of the signal in the receiver coil C. Time it takes for the flip angle to reach the Ernst angle of peak signal D. Time between two 90º RF pulses
D. Time between two 90º RF pulses The repetition time (TR) is the time between two 90º RF pulses
In a Fast Spin Echo sequence, the effective TE are the echoes that are encoded: A. In the first portion of the sequence B. In the outer edges of k-space C. With a high amplitude phase encoding gradient D. With a low amplitude phase encoding gradient
D. With a low amplitude phase encoding gradient In a Fast Spin Echo sequence, the effective TE are the echoes that are encoded with a low amplitude phase encoding gradient. This would occur at the line that is closest to the center of k-space (k0)
Water has a __________ T1 relaxation time and a ________ T2 relaxation time. A. short; short B. short; long C. long; short D. long; long
D. long; long
Calculate the voxel volume for a fast spin echo sequence with the following parameters: FOV 34cm, TR 3000, TE 120, 512 x 512 matrix, 3 NEX, 6 mm slice thickness, 12 ETL. A. 0.44 mm2 B. 0.66 mm2 C. 1.32 mm3 D. 3.48 mm3 E. 2.64 mm3 F. 6.44 mm3
E. 2.64 mm3 340 ÷ 512 = 0.66 0.66 x 0.66 = 0.44mm2 (pixel area) 0.44 x 6 = 2.64mm3 (voxel volume)
Calculate the voxel volume for a fast spin echo sequence with the following parameters: FOV 28cm, TR 2000, TE 30, 256 x 320 matrix, 2 NEX, 4 mm slice thickness, 8 ETL. A. 0.76 mm2 B. 0.88 mm2 C. 0.96 mm3 D. 1.97 mm3 E. 3.84 mm3 F. 4.96 mm3
E. 3.84 mm3 FOV ÷ phase matrix = phase dimension pixel FOV ÷ frequency matrix = frequency pixel Multiply phase pixel size x frequency pixel size = Pixel area (answer squared2) Pixel area x slice thickness = Voxel volume (answer cubic3) Convert 28cm to 280 mm before calculating. 280 ÷ 256 = 1.09mm (phase dimension) 280 ÷ 320 = 0.88mm (frequency dimension) 1.09 x 0.88 = 0.96mm2 (pixel area) 0.96mm x 4 (sl thickness) = 3.84mm3 (voxel volume)
Which of the following can be considered an advantage of selecting a 3D acquisition as opposed to a 2D acquisition? A. The slices have a greater SNR B. No crosstalk C. Longer repetition times D. All of the above E. A & B only
E. A & B only Long TR's are not advantageous in a 3D acquisition, but a 3D sequence does provide greater SNR and elimination of crosstalk artifacts.
The overall signal-to-noise ratio will increase in 3D volume imaging when there is an increase in: A. Number of slices or partitions B. TE C. Phase Matrix D. Field of View E. A and/or D
E. A and/or D
Signal to Noise Ratio (SNR) would increase in a 3D volume acquisition with an increase in: A. TE B. Slices C. Field of view D. All of the above E. B and/or C only
E. B and/or C only Signal to Noise Ratio (SNR) would increase in a 3D volume acquisition with an increase in the Field of View or the number of slices.
All of the following are properties of T2 weighting EXCEPT: A. Long TR, long TE are the parameter requirements B. Spin spin C. Transverse magnetization D. 63% decay E. Flip angle controls contrast
E. Flip angle controls contrast Contrast is controlled by TE in a T2 weighted sequence.
Contraindications for IV gadolinium contrast use are: A. Pregnant or nursing mothers B. Sickle cell anemia C. Insulin dependent diabetes D. All of the above E. None of the above
E. None of the above
All of the following are examples of EXTRINSIC contrast parameters EXCEPT: A. TR B. TE C. T1 time D. Flip angle E. TI
E. TI
In order to produce an echo in a gradient echo pulse sequence, a ___________ is used. A. RF pulse B. Gradient field C. Combination of two RF pulses D. 180° pulse, then 90° pulse E. All of the above F. A & B only
F. A & B only
Decreasing the receiver bandwidth (utilizing a narrow BW): A. Reduces readout time B. Increases readout time C. Does not affect the readout time D. Increases SNR E. A and D only F. B and D only
F. B and D only Decreasing the receiver bandwidth (utilizing a narrow BW) increases SNR and readout time -- increases the sampling time and lengthens the sequence timing, creating longer minimum TR and TE values
Reducing the TR: A. Increases the SNR of the image B. Decreases the SNR of the image C. Decreases the contrast based on the T2 relaxation time D. Increases saturation effects E. A and D only F. B and D only G. B, C and D only
F. B and D only Reducing the TR decreases the SNR of the image and increases saturation effects
Increasing the TE: A. Increases the contrast based on T1 tissue relaxation times B. Decreases the SNR of the image C. Decreases the contrast based on T2 tissue relaxation times D. Increases the contrast based on T2 relaxation times E. A and B only F. B and C only G. B and D only
G. B and D only Reducing the TR decreases the SNR of the image and increases saturation effects
