All of the following artifacts except ________ occur along the phase encoding axis
chemical shift (occurs along the frequency axis)
Magnetic susceptibility artifacts are more prominent with _____________ sequences
GRE
A remedy for a Gibbs truncation artifact would be:
To correct for Gibbs truncation artifact, increase the number of phase encodings or reduce the FOV (while maintaining matrix)
The largest ventricle in the heart is the _______ and is identified by Letter ____ in Image 66.
Left ventricle, D
Calculate the effective TR for a patient with a heart rate of 70 beats / min.
60,000 / 70 = 857
The HEIGHT of a peak on an MR spectrum correlates to the _________ of a substance that was detected.
AMOUNT
Contrast in Diffusion Weighted Imaging (DWI) depends on:I. The degree to which molecular mobility is impaired (water restriction)II. The sensitivity of the sequence to Brownian motionIII. T1 relaxation timeIV. The direction of water diffusionV. T2 relaxation time
Contrast in Diffusion Weighted Imaging (DWI) depends on the degree to which molecular mobility is impaired (water restriction), the sensitivity of the sequence to Brownian motion, and the direction of water diffusion
The final result in a perfusion study is
A set of calculated images which indicate various flow characteristics
The final result in a spectroscopy study is
A spectrum of specific detected metabolite-Spectroscopy (MRS) allows doctors to obtain biochemical information about the chemical components in tissues (metabolites) of the human body in a non-invasive way.
The imaging technique that employs a very rapid pulse sequence while the patient is at rest or performing a task is:
functional MRI
the corpus callosum primarily consists of
white matter
If the TR in a gradient echo sequence is less than the T2 (or T2*), the resulting condition is known as:
steady state
A gradient echo sequence in which all the remaining residual transverse magnetization is removed prior to the next excitation pulse is known as:
incoherent or spoiled
In a Fast Spin Echo (FSE) sequence, acquired with a long TE, yielding T2 weighted images, scan time can be reduced by:
using longer ETL
In a Fast Spin Echo (FSE) sequence, acquired with a short echo time (TE), yielding T1 or PD weighted images, blurring can be reduced by
using shorter ETL
The structures that comprise the rotator cuff in the shoulder are:I. Deltoid muscleII. Subscapularis muscle and tendonIII. Infraspinatus muscle and tendonIV. Teres minor muscle and tendonV. Supraspinatus muscle and tendonVI. Trapezius muscle and tendon
II, III, IV and V-The rotator cuff is comprised of the subscapularis muscle and tendon, infraspinatus muscle and tendon,teres minor muscle and tendon and the supraspinatus muscle and tendon
T2 weighted FLAIR (fluid attenuated inversion recovery) sequences are typically used for evaluation of:
white matter disease
Short TAU inversion recovery (STIR) sequences are typically used for the evaluation of all the following EXCEPT:
fluid CSF - Short TAU inversion recovery (STIR) sequences are typically used for the evaluation of compression fracture, lesions within retro-orbital fat, musculoskeletal contusions and fat suppression
If the pulse sequence shown in Image 77 were a fast spin echo sequence, the number of lines of k-space filled for each TR period would be:
2
When a gradient echo sequence is selected for fast, breath hold dynamic contrast-enhanced imaging of the abdomen, _____________ is utilized.
spoiling
Gradient echo sequences requiring high signal from fluid are known as all of the following EXCEPT:
incoherent GRE- Gradient echo sequences requiring high signal from fluid are known as T2* gradient echo, Steady-state gradient echo or coherent gradient echo. Incoherent gradient echo (or spoiled gradient echo) sequences yield T1 contrast due to the removal of residual transverse magnetization before the next excitation.
Dynamic enhanced MRA sequences of the mesenteric arteries are performed using
incoherent GRE
Gradient echo sequences can yield either T1 or T2* characteristics, with influences caused by all of the following EXCEPT
inversion time
Which of the following field strengths would require the shortest TI time to suppress the signal from fat when performing a STIR sequence in an MRI of the ankle?
0.5t
If the desire is to null the signal from a specific tissue using an inversion recovery sequence, the inversion time (TI) selected should be ______ of the T1 relaxation time of that tissue.
69%
When parallel imaging techniques are utilized, a low resolution __________ is acquired prior to the acquisition.
calibration scan
In a Fast Spin Echo sequence, the number of shots is calculated by:
# of phase encoding / ETL
In a medical malpractice lawsuit, the ______ must be able to prove medical malpractice.
patient plaintiff
Healthcare workers generally practice ___________, which states the "goal is to do no harm.
beneficence
Referencing the White Paper on MRI safety, individuals identified as "Level 2" personnel include:
Those with extensive MRI safety training, including the magnetic, gradient and RF fields
Referencing the White Paper on MRI safety, individuals identified as "Level 1" personnel include:
Those with limited MRI safety training
Which of the following is NOT a type of fomite found in an MRI environment?
injection syringe
Diseases, such as malaria, in which microorganisms are transferred via an insect, come under the classification of __________ infections.
vector borne
Which type of blood cell is responsible for phagocytosis?
leukocyte
The source of infection where pathogens thrive in numbers sufficient to cause a threat is known as a:
reservoir
Droplet contamination frequently occurs via
coughing
Referencing the Centers for Disease Control and Prevention (CDC), what type of isolation precautions should be used for HIV-positive patients in the MRI suite?
standard (universal)
During movement or transfer of patients, a urinary collection bag should be placed:
below the level of the urinary bladder
Another term used for "fever" is:
febrile
A technologist may be permitted to administer oxygen in an emergency situation. The most common rate used is:
2L/min
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 contrastII. lower signal-to-noise ratioIII. more T1 contrast
I and II only
As the TE is increased, I. The available number of slices is increasedII. The available number of slices is decreasedIII. SNR increasesIV. T1 contrast is maximized
II only
Which of the following sequences is the most insensitive to magnetic field inhomogeneity?
spin echo
As the TR is increasedI. SNR is increasedII. Available number of slices is increasedIII. T2 information is maximized
I and II only- As the TR is increased, SNR is increased and the available number of slices is increased.
CSF suppression is performed with which type of technique?
FLAIR (Fluid Attenuated Inversion Recovery) is a technique that nulls the signal from CSF in order to achieve better white matter visualization
mage 73 is a diagram of which pulse sequence?
fast spin echo
Image 75 is an example of which type of sequence?
inversion recovery
Letter A in Image 75 represents?- letter A is above the first 180 deg pluse
inverting 180 deg pulse
Image 74 is a diagram of which type of pulse sequence?only on echo in top row
gradient echo
What element in the body is the principal nucleus utilized in clinical MR imaging
hydrogen
The extent to which a material or tissue becomes magnetized in an external magnetic field is called:
magnetic inversion
The energy used to form MRI images is ____________ the patient's tissues.
emitted from
The _________ is defined as the resonant frequency, and is equal to the product of the magnetic field and the gyromagnetic ratio.
precessional frequency
Force on an object in an magnetic environment depends on:I. Mass of the objectII. Strength of the magnetic fieldIII. Strength of the RF fieldIV. Ferromagnetic properties of the object
I, II and IV
A magnetic vector possesses attributes of both __________ and _____________
magnitude and direction
Immediately following the application of the 90° RF pulse, the precessing protons:
Immediately following the application of the 90° RF pulse, the precessing protons begin to precess in phase and tip into the transverse plane.
Image 43 is an example of an MR angiography of the abdominal aorta and runoff of the lower extremities. This was acquired with dynamic contrast enhancement and:
Stepping table motion from the abdomen down to the feet following the contrast injection
When imaging the female pelvis, the most optimal view for evaluation of the ovaries is the:
coronal
When imaging the female pelvis, the most optimal view for evaluation of the uterus is the:
sagital
Which of the following parameter adjustments help to improve SNR in an MR image?I. Increase TRII.Reduce Phase MatrixIII. Reduce Pixel SizeIV. Increase FOVV. Reduce rBWVI. Increase rBWVII. Increase NSAVIII. Decrease NSAIX. Increase ETLX. Decrease ETL
I, II, IV, V, VII and X
Which of the following parameter adjustments reduce the overall SNR in an MR image?I. Decrease TRII.Reduce Phase MatrixIII. Reduce Pixel SizeIV. Decrease FOVV. Reduce rBWVI. Increase rBWVII. Increase NEXVIII. Decrease NEXIX. Increase ETLX. Decrease ETL
I, III, IV, VI, VIII and IX- A Decrease in TR, Reduction in Pixel Size, Decrease in FOV, Increase (widening) of the receiver Bandwidth, Decrease in NEX and an Increase in #ETL all negatively impact SNR in an MR image
Fat has a _______ T1 relaxation time and a ________ T2 relaxation time.
short, short
Water has a __________ T1 relaxation time and a ________ T2 relaxation time.
long, long
Which of the following is NOT affected by changing the slice thickness?
the T2 contrast
Which parameter combination will yield the best spatial resolution?
3mm slice thickness, 256 x 256 matrix
In a fast spin echo sequence with a 25 cm FOV, 224 x 320 matrix, TR 2500, 100 TE, 3mm slice thickness, 12 ETL and 4 NEX, the scan time would be:
3 minutes 7 secondsScan time formula: TR x Phase Matrix x NEX ÷ ETL = total in milliseconds, then ÷ 1000 to achieve scan time in seconds. In this example, TR2500 x 224ph encodings x 4NEX / 12ETL /1000. Be careful if you divide by 60 to achieve the scan time in decimal format (This example computes to 186.6 seconds, if you divide by 60 you get 3.11 seconds, which is 3 minutes 7 seconds, not 3 minutes 11 seconds)
Reducing the FOV (field of view) only will result in:
Decreased signal-to-noise
The smallest object that can be resolved in an image acquired with a 24cm FOV and a 272 x 272 matrix is _________ mm.
0.88 mm 272 / 24
What would the scan time be in a 3D volume acquisition as follows: TR 24 ms, TE 7 ms, Flip Angle 15°, FOV 20cm, 2mm slice thickness, 76 slices, 176 x 256 matrix, 1 NEX?
5min 21 sec
Choose the correct slice thickness to create an isotropic voxel for the following: TR 2000, TE 90, Matrix 272 x 272, FOV 24cm.
0.88An isotropic voxel has equal measurements in all three dimensions (phase, frequency and slice direction) FOV/Matrix = 0.88mm
The pixel size of the images which result from a 3D acquisition using a 260mm FOV, a 320 x 320 matrix, 32 slices and a volume of 64 mm is:
0.81 x 0.81
All of the following would aid in reducing scan time EXCEPT:
reduction in ETL
All of the following yield a higher signal-to-noise ratio EXCEPT:
increase in TE
RF energy used in MRI is classified as:
Low energy, nonionizing radiation
If the flip angle is doubled, RF deposition increases by a factor of:
4
Calculate the voxel volume for the following pulse sequence: TR 2000, TE 85, FOV 24cm, Matrix 272 x 320, 3mm slice thickness, 3 NSA.
1.98mm3
Calculate the pixel area for the following sequence: TR 4000, TE 120, FOV 36cm, 408 x 512 matrix, 2 NEX, ETL 12.
0.62 mm2FOV/matrix x FOV/matrix = pixel area. 360/408 x 360/512 = 0.62 mm2.
_______ is when only half the views of k-space are filled in the frequency axis
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.
As the number of phase encodings is increased from 256 to 512, SNR (signal to noise ratio):
decreases
The readout gradient is usually turned on during the sampling or readout of the peak echo and also during which other process?
Frequency encoding- The readout gradient is usually turned on during the sampling or readout of the peak echo and also during frequency encoding.
A narrow receiver bandwidth:
Increases susceptibility artifact
What effect would using a steep slice select slope and/or narrow bandwidth have on slice thickness?
Slices will be thin- Steep slice select gradient slope yields thin slice thickness.
Creating additional images in various planes from a 3D data set is accomplished by a technique known as:
Multi-Planar reconstruction (MPR)
The process that digitizes the MR signals is known as:
Fourier transform
To increase the voxel volume, which parameters would be adjusted?
FOV, slice thickness and matrix
The Ernst angle can be defined as the optimal ___________ that yields the ____________ signal for a particular spin in the least amount of time.
fill angle, max
Which of the following parameter adjustments will SHORTEN scan time in an MR pulse sequence?I. Decrease TRII. Increase TRIII. Increase ETLIV. Decrease ETLV. Decrease NEXVI. Increase NEXVII. Enable Half-fourierVIII. Increase parallel imaging factorIX. Decrease parallel imaging factorX. Enable anti-aliasing
I. decrease TRIII. increase ETLV. decrease NEXVII. enable half fourierVIII increase parallel imaging factor
Which of the following parameter adjustments will LENGTHEN scan time in an MR pulse sequence?I. Decrease TRII. Increase TRIII. Increase ETLIV. Decrease ETLV. Decrease NEXVI. Increase NEXVII. Enable Half-fourierVIII. Increase parallel imaging factorIX. Decrease parallel imaging factorX. Enable anti-aliasing
II. increase TRIV decrease ETLVI increase NEXIX decrease parallel imaging factor
The _____________ imaging plane would be the most optimal slice orientation for evaluation of Arnold Chiari Malformation and its inferior cerebellar tonsillar herniation.
sagittal
When imaging a hemorrhagic infarct in the brain, which pulse sequence would demonstrate the magnetic susceptibility effects better?
Gradient echo- Due to the lack of 180° RF refocusing pulse, the gradient echo sequence is more susceptible to magnetic field inhomogeneities, such as hemosiderin from blood products. The hemosiderin is highly magnetic because it is principally iron.
_______ sequences are performed to suppress CSF (cerebro-spinal fluid)and aid in the detection of demyelination.
FLAIR-suppress the signal from CSF to detect small white matter lesions, tumors, and evaluation of stroke
The medial and lateral rectus muscles are located in the:
eyes
In the TMJ's, the articular disc lies between what two anatomical structures?
Mandibular fossa and mandibular condyle
f the third ventricle is dilated, but the fourth ventricle is not, there would then be pathology associated with:
aqueduct of sylvius
Which fissure divides the frontal and parietal lobes from the temporal lobes?
Sylvian fissure
The __________________ runs the length of the falx cerebri.
superior sagittal sinus
When performing MRI to rule out brain tumors, the weighted images acquired to evaluate the extent of lesion involvement, after injection of gadolinium, are:
T1 weighting
If a 192 phase resolution is required, the TR must then be repeated _______ times (for 1 NEX).
192
The phase encoding step is performed:
Prior to frequency encoding
In what orientation would a tear of the collateral ligaments of the knee be best visualized?
coronal
The optimal imaging plane for visualization of a TFCC tear is:
coronal
On a T2 weighted image, edema appears bright because it has a _________ relaxation time.
long t2
All of the following comprise the biliary tree EXCEPT:
splenic duct
What protocol would be selected to rule out islet cell tumor?
Pancreas-Well or intermediately differentiated Pancreatic Neuroendocrine Tumors are sometimes called islet cell tumors, and are diagnosed with an abdominal MRI exam with attention to the pancreas.
The common carotid artery bifurcates into the internal and external carotid artery at the level of the:
C3-4 disc space
In order to acquire an intracranial arterial blood flow sequence, a presaturation pulse would be applied in which location?
superior to slice group
A major advantage of a 2D time of flight over a 3D time of flight sequence is the ability to:
Image larger areas without saturation of flowing blood- 2D TOF is generally utilized when larger regions of anatomy are required to be imaged, with typically thicker slices than 3D TOF.
A disadvantage of TOF MRA is high signal in some background tissues. To minimize signal from background tissues, TE should be selected that enable the signals from fat and water to be:
out of phase- Out of phase TE's minimize signals from background stationary tissues in time of flight MR angiography.
Phase contrast MRA techniques produce images in which the signal intensity within the vessel is dependent upon the:
velocity of the flowing blood
The first major branch of the abdominal aorta is the _______.
celiac artery
In a contrast enhanced MR angiography of the abdominal arteries, the IV gadolinium would enhance in which order?
Celiac, superior mesenteric, renal, inferior mesenteric
When imaging a geriatric patient, while performing a PCA MRA sequence, what imaging parameter might the operator adjust?
VENC
The ligamentum flavum can be found in which part of the body?
spine
On T1 weighted images of the spine, the CSF (cerebrospinal fluid) appears:
Hypointense to the spinal cord
In a cross sectional view of the MR magnet design, which coils are closest to the patient?
RF coils
The purpose of shimming the magnet is to:
Make the B0 field as homogenous as possible
The unit of measurement of the magnetic field surrounding the periphery of the MR scanner is expressed as:
guass
Active shielding can be defined as:
Superconducting windings within the MR scanner, reducing the fringe magnetic field
___________ could be used to line the walls and/or floors of the MR magnet room to reduce the fringe field, and is defined as __________ shielding.
steel, passive
Which of the following has been documented to cause muscle contractions, cardiac arrhythmias, mild cutaneous sensations and visual light flashes?
Time varying magnetic fields (TVMF -- gradient)have been documented to cause muscle contractions, cardiac arrhythmias, mild cutaneous sensations and visual light flashes.
The gradient rise time is defined as the:
time it takes for the gradient to reach its full amplitude
The gradient slew rate is the:
Rate of speed of ascent or descent of a gradient from zero to its maximum amplitude
Magnetic field inhomogeneity is expressed in:
parts per million
A technique utilized to reduce the MRI scan time which requires the use of an array coil is:
parallel imaging
What is the percentage of patients reported to have allergic reactions to gadolinium contrast agents?
1%
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.
16 mL
To produce an image based on differences in T1, the time interval between 90° excitation pulses should be:
short
All of the following are examples of INTRINSIC contrast parameters in tissues EXCEPT:
TR
Chemical or spectral fat suppression techniques suppress fat signal based on the:
Precessional frequency of fat
Hemangiomas in the liver are typically benign lesions, and are best visualized with:
delayed images
In an MRA sequence, the removal of signal from vessels is accomplished by:
spatial presaturation
Which of the following, in an MRA sequence, aids in minimizing the loss of signal due to dephasing within a voxel:
the longer the TE, the more time given for intravoxel dephasing, resulting in signal loss from within the vessel. Larger voxels lead to an increase in inhomogeneities within the voxel, increasing intravoxel dephasing and reducing signal intensity.
Increasing the flip angle:
Increases SNR up to the Ernst angle
Reducing the flip angle yields images with what change in image contrast?
less T1 information
Reducing the TE yields images with what change in image contrast?
Decreased T2 information
The MRI system component that produces the magnetization of proton spins (alignment) is known as the:
main magnet
The MRI system component that provides the ability to perform spatial encoding is the
gradient system
In a superconducting magnet, the magnetic field strength is increased by increasing the:
turns of wire
Permanent magnets with a vertical magnetic field use surface coils that are:
solenoids
In order to generate thin slices, a ___________ is used.I. Steep slice selection gradientII. High amplitude slice select gradientIII. Low amplitude slice select gradientIV. Narrow transmit bandwidth (tBW)V. Wide transmit bandwidth (tBW)VI. Narrow receiver bandwidth (rBW)
I. steep slice selection gradientII. high amplitude slice select gradient IV. narrow transmit bandwidth
The receiver bandwidth (rBW) affects:I. Signal-to-noise ratio (SNR)II. Slice thicknessIII. Chemical shiftIV. Spatial resolution
I. SNRIII. chemical shift
The B1 magnetic field is produced by a:
Radiofrequency coil
Shimming in MRI can be performed by all the following EXCEPT:
turning the shim off and on rapidly
An adverse reaction or complication caused by treatment from a healthcare professional is called:
iastrogenic
The 2003 FDA revision on RF absorption limits the absorption to ______________ for the head.
3.0w/kg for 10 mins
When imaging the spine, to rule out metastatic lesions of the spinal cord, contrast enhancement is used with T1 weighted images because:
Metastatic lesions (in the cord) enhance and normal cord does not
The difference in chemical shift is approximately ______ parts-per-million.
3.5ppm
A STIR sequence with a TI time of 160 ms will null signal from fat at what field strength?
1.5t
Which of the following combinations of flip angle (FA) and TR would produce a T2 weighted gradient echo?
450 TR, 30 flip angle
To produce a high quality reformatted image, the:
Acquisition voxel should be isotropic
Collecting the low frequency (high amplitude signal) data points in k-space at the start of the scan (in a spiral fashion) is known as:
Collecting the low frequency (high amplitude signal) data points in k-space at the start of the scan (in a spiral fashion) is known as elliptic centric k-space filling.
During dynamic enhanced imaging for vasculature or visceral structures, contrast is administered and k-space is filled with __________ to ensure that the contrast enhancement is well visualized.
centric
________ sequences use T1 gradient echoes with TR and FA selections to suppress signal from stationary tissues, visualizing flowing blood by flow-related enhancement, whereas __________ sequences use T2 gradient echoes with parameter selections that suppress stationary tissue and rely on velocity-induced phase shifts for vascular signal.
TOF MRA sequences use T1 gradient echoes with TR and FA selections to suppress signal from stationary tissues, visualizing flowing blood by flow-related enhancement, whereas PC MRA sequences use T2 gradient echoes that rely on velocity-induced phase shifts for vascular signal
Which of the following best describes an EPI sequence
a train of gradient echoes
Which of the following best describes an IR sequence?
A 180° pulse followed by a 90°/180° combination
Which of the following best describes a FSE sequence?
A train of spin echoes
Reducing the FOV by a factor of 2 will reduce the voxel volume by a factor of:
4
Calculate the available imaging time for a patient with a heart rate of 90 beats/min, trigger window 15% and trigger delay of 80ms.
487 ms