Mid Term Exam Flashcards
T/F: All contrast media is potentially harmful and should be used knowledgeably.
True
T/F: Intravascular contrast media administration is performed under the supervision of a licensed physician.
True
T/F: Technical and nursing personnel injecting contrast media must be knowledgeable in the recognition of, and able to assist in the treatment of any adverse reaction.
True
T/F: Literature in the MRI community and manufacturer recommendations lists the dosage of intravenous gadolinium chelate contrast to be 0.1 mmol/kg of body weight.
True
T/F: Any and all adverse events, incidents or “near incidents” that occur pertaining to MR safety are to be reported to the MRI Medical Director, the MRI Department Supervisor or the Radiology Administrator immediately.
True
T/F: A student may review and sign the MRI screening sheet prior to an individual entering the scan room.
False
T/F: The Medical Director will be involved with the introduction of new policies and procedures as needed with the advancement of technologies and procedures in the MRI environment.
True
T/F: Zone III – This area is synonymous with the MR scanner room itself.
False
T/F: Lenz’s Law is an important consideration with non-ferromagnetic objects.
True
T/F: Having undergone a previous MRI successfully with an implanted device indicates that the device is MRI safe.
False
T/F: The potential for translational forces (“projectile forces”) exists at any field strength.
True
T/F: After a quench the patient and personnel should evacuate the area immediately.
True
Which of the following describe T1 Recovery? (Choose all that apply)
Spin lattice relaxation
The time it takes 63% of transverse magnetization to decay in the tissue.
Caused by the nuclei giving up their energy to the surrounding environment or lattice.
Spin-spin relaxation that results in decay or loss of coherent transverse magnetization.
Spin lattice relaxation
Caused by the nuclei giving up their energy to the surrounding environment or lattice.
What MUST be done prior to anyone entering the scan room? (Select the BEST answer)
Pat the patient down for metal objects.
A screening sheet must be filled out and in the patient’s chart.
The patient must be scanned with the metal detector.
The completed screening sheet must be signed by a level II staff member and the patient must be scanned with the metal detector, prior to admittance to the MRI scan room.
The completed screening sheet must be signed by a level II staff member and the patient must be scanned with the metal detector, prior to admittance to the MRI scan room.
What happens to the alignment of hydrogen protons when placed in an external magnetic field? (Check all that apply)
Nothing until an RF pulse is applied.
The magnetic moments of the nuclei align with or against the main magnetic field.
More nuclei oppose the main magnetic field than line up with the main magnetic field.
Slightly more nuclei line up with the main magnetic field than against it.
The magnetic moments of the nuclei align with or against the main magnetic field.
Slightly more nuclei line up with the main magnetic field than against it.
Where do we look up the safety of an implanted device? (Check all that apply)
www.MRISafety.com
Shellock’s reference manual
The manufacturer’s website
If we remember that it is a safe implant, there is no need to look it up again.
www.MRISafety.com
Shellock’s reference manual
The manufacturer’s website
What effect does the magneto-hemodynamic effect have? Is this a permanent effect? (Check all that apply)
Increase in the amplitude of the “R” wave on EKG gating.
Increase in the amplitude of the “T” wave on EKG gating.
Reversible effect– EKG tracing returns to normal when the patient is removed from the static magnetic field.
Permanent effect– EKG tracing continues to show an elevated wave form after the patient has had an MRI exam.
Increase in the amplitude of the “T” wave on EKG gating.
Reversible effect– EKG tracing returns to normal when the patient is removed from the static magnetic field.
What is the gyromagnetic ratio of hydrogen?
- 28 MHz/T
- 8 MHz/T
- 57 MHz/T
- 57 MHz/G
42.57 MHz/T
Select the three components of the magnetic field from those listed below.
Static Magnetic Field
Faraday’s Field
Radiofrequency Fields
Time Varying Magnetic Fields
Precessional Frequency Field
Static Magnetic Field
Radiofrequency Fields
Time Varying Magnetic Fields
What are the guidelines for pregnant employees? (Choose all that apply)
No changes to pregnant employees work environment in MRI. Everyone knows that MRI doesn’t use radiation.
Pregnant employees may enter the scan room, but should leave before scanning begins.
Pregnant employees are exempt from scanning and may only do paperwork.
Pregnant employees MUST transfer to x-ray once they’ve announced their pregnancy to the MRI department.
Pregnant employees may enter the scan room, but should leave before scanning begins.
T/F: The gyromagnetic ratio expresses the relationship between the angular momentum and the magnetic moment of each MR active nucleus.
True
Identify which of the following describe a “fringe field.” (Select all that apply)
The stray magnetic field outside the bore of the magnet.
An area on the outskirts of the magnet– generally two feet long by three feet wide.
Active or passive shielding is used to reduce the size of the fringe field.
The fringe field is not confined by walls, floors, or ceilings.
The stray magnetic field outside the bore of the magnet.
Active or passive shielding is used to reduce the size of the fringe field.
The fringe field is not confined by walls, floors, or ceilings.
What would you do in the event of a CODE BLUE in MRI? (Select all that apply)
Stay with the patient in the scan room until help arrives.
Begin CPR.
Activate the Code Blue response process (push the Code Blue button)
Get the patient out of the scanner and into Zone III; locking the scan room door and monitoring it when other Code Team members arrive
Begin CPR.
Activate the Code Blue response process (push the Code Blue button)
Get the patient out of the scanner and into Zone III; locking the scan room door and monitoring it when other Code Team members arrive
What are the two results of resonance? (Choose from the list below)
The NMV moves out of alignment and away from B0.
The NMV moves into a repeating pattern of /- 100 MHZ.
The magnetic momements of hydrogen nuclei move out of phase with each other.
The magnetic moments of hydrogen nuclei move into phase with each other.
The NMV moves out of alignment and away from B0.
The magnetic moments of hydrogen nuclei move into phase with each other.
T/F: The “warm zone” in MRI is the scan room itself.
False
Which of the following best describe spin-lattice relaxation? (Choose all that apply)
T2 Decay
T1 Recovery
Time it takes 88% of the longitudinal magnetization to recover in tissue.
Nuclei give up energy to the surrounding environment, resulting in longitudinal recovery.
T1 Recovery
Nuclei give up energy to the surrounding environment, resulting in longitudinal recovery.
What makes a nucleus an MR active nucleus? (Select all that apply)
Odd mass numbers
Atoms with a balanced mass number
Nuclei with a net spin or angular momentum
None of the above
Odd mass numbers
Nuclei with a net spin or angular momentum
T/F: We ALWAYS scan pregnant patients with contrast.
False
T/F: For resonance of hydrogen to occur, RF at EXACTLY the Larmor frequency of hydrogen must be applied.
True
What are the three types of motion present in an atom? (Select all that apply)
Electrons spinning on their own axis.
Nuclei spinning around each other.
Electrons orbiting the nucleus.
The nucleus itself spinning about its own axis.
Electrons spinning on their own axis.
Electrons orbiting the nucleus.
The nucleus itself spinning about its own axis.
Identify the two factors that determine which hydrogen nuclei align parallel and which align anti-parallel with the main magnetic field.
The strength of the external magnetic field
How many nuclei there are in each patient’s body
The thermal energy level of the nuclei
The orientation of the patient in the scanner (head first vs. feet first)
The strength of the external magnetic field
The thermal energy level of the nuclei
Which way does the main magnetic field run in permanent magnets?
Horizontally
Vertically
Side to Side
Down the bore of the magnet
Vertically
What is the terminal velocity of a paperclip at 1.5T?
64 mph
55mph
40mph
None- not attracted
40mph
Which of the following describe the purpose of gradients in MRI? (Choose all that apply)
Alter the main magnetic field in a linear fashion
Change thermal equilibrium
Spatially encode data
Cause electrons to spin on their own axis
Alter the main magnetic field in a linear fashion
Spatially encode data
What does SAR stand for?
Special Atomic Rate
Start Atoms Rolling
Specific Absorption Rate
Specific Atomic Rate
Specific Absorption Rate
What does the net magnetization vector (NMV) represent?
The type of MR active nuclei present
The relative number of electrons to protons
The atomic number of the nuclei present
The relative balance of spin-up to spin-down nuclei
The relative balance of spin-up to spin-down nuclei
Which way does the main magnetic field run in superconducting magnets?
Along the bore of the magnet (horizontal)
Along the Y-axis
Vertically
Side to side
Along the bore of the magnet (horizontal)
What is the best device to use when monitoring a patient’s status in MRI?
Blood pressure cuff
Pulse ox
EKG
Auditory monitoring
Pulse ox
What does the Larmor Equation calculate?
The NMV
The precessional frequency
The gyromagnetic ratio
The atomic mass
The precessional frequency
What is the T2 relaxation time of tissue?
[Hint: Think about which axis T2 relaxation is occurring in (longitudinal vs. transverse) and whether T2 relaxation indicates recovery vs. decay.]
The time it takes 43% of the longitudinal magnetization to recover in the tissue.
The time it takes 63% of the transverse magnetization to recover in the tissue.
The time it takes 63% of the longitudinal magnetization to decay in the tissue.
The time it takes 63% of the transverse magnetization to decay in the tissue.
The time it takes 63% of the transverse magnetization to decay in the tissue.
What is another term for T2 Decay?
Spin-lattice relaxation
Spin-spin relaxation
T1 recovery
NMV
Spin-spin relaxation
How do gradients affect the main magnetic field? (Select all that apply)
They add to the main magnetic field
They subtract from the main magnetic field
They alter the main magnetic field in a linear fashion
They give the image its shades of gray
They add to the main magnetic field
They subtract from the main magnetic field
They alter the main magnetic field in a linear fashion
T/F: Rewinders are gradients that rephase.
True
Which of the following controls T2* weighting in gradient echo?
TE
TR
Flip angle
TR and flip angle
TE
What controls the polarity of a gradient?
The steepness of the slice select gradient
The sharpness of the frequency readout
The direction of the current through the gradient coil
The strength of the main magnetic field
The direction of the current through the gradient coil
T/F: TR controls T2 weighting.
False
Which of the following is known as the basic MRI contrast?
T1 weighting
T2 weighting
Gray imaging
Proton density weighting
Proton density weighting
Choose extrinsic contrast parameters from the list below.
T1 Recovery Time TR Proton Density Flip Angle Flow TE b Value
TR
Flip Angle
TE
b Value
What are the two extremes of contrast in MRI?
T1 Recovery
Fat
Air
Water
Fat
Water
T/F: The TE is twice the TAU.
True
T2* decay is faster than T2 decay since it is a combination of which two of the following effects?
T1 decay with spin echo
T2 decay itself
Dephasing due to magnetic field inhomogeneities
*weighting
T2 decay itself
Dephasing due to magnetic field inhomogeneities
Which of the following best describes a T1 weighted image? (Select all that apply)
Bright water
Bright fat
Dark Water
Dark Fat
Bright fat
Dark Water
Which of the following statements is true:
Spin-spin interactions drive T1 contrast
Slow tumbling molecules lead to decreased spin-spin dephasing
Fast tumbling molecules lead to increased spin-spin dephasing
Spin-spin interactions drive T2 contrast
Spin-spin interactions drive T2 contrast
What is the approximate T1 relaxation time of water at 1T?
200 ms
500 ms
2000 ms
2500 ms
2500 ms
Which of the following items are T1 and T2 relaxation times dependent on? (hint: there are three)
How well the molecular tumbling rate matches the Larmor frequency of hydrogen
Spin-spin interactions of oxygen atoms
How closely packed the molecules are
The inherent energy of the tissue
The number of electrons orbiting the nucleus
How well the molecular tumbling rate matches the Larmor frequency of hydrogen
How closely packed the molecules are
The inherent energy of the tissue
T/F: Intrinsic parameters are those that cannot be changed because they are inherent to the body’s tissues.
True
To achieve T1 weighting in gradient echo sequences, the flip angle should be ______.
Large
Small
No flip angle should be used
Large
T/F: Spin echo sequences do not compensate for magnetic field inhomogeneities, while gradient echo sequences do compensate for magnetic field inhomogeneities.
False
___ controls the amount of T1 weighting.
TR
TE
TI
PD
TR
For PD weighting, the TR must be ______.
Long
Short
Intermediate
T1
Long
T/F: Generally speaking, gradient echo sequences are faster than spin echo sequences.
True
For T2 weighting, the TE must be _____.
short
long
intermediate
PD
long
Gradients that dephase are called __________.
rewinders
weighted
spoilers
variable flip angles
spoilers
The spin echo is created by:
The application of a long TE
The application of a rewinding gradient
A 180 degree RF pulse
A rapid TI
A 180 degree RF pulse
Gradients are used to rephase spins in gradient echo sequences because:
The resulting images have less artifact than spin echo images
They are faster to apply than an RF pulse
They rephase spins more completely than an RF pulse
They result in images with better contrast resolution
They are faster to apply than an RF pulse
Which of the following controls T1 weighting in gradient echo?
TI
TE
Gradient amplitude
TR and flip angle
TR and flip angle
Saturation results in T1 weighting because:
The flip angle used was small so vectors are not pushed beyond the transverse plane
Only occurs when the TR is long as this allows for full recovery
Vectors are pushed beyond the transverse plane because they were completely recovered before the RF excitation pulse
Vectors are pushed beyond the transverse plane as they were incompletely recovered before the RF excitation pulse
Vectors are pushed beyond the transverse plane as they were incompletely recovered before the RF excitation pulse
T/F: nhomogeneities are areas within the magnetic field that do not exactly match the external magnetic field strength.
True
What does the phase encoding gradient do?
Encode data along the LONG axis of the anatomy
Encode data along the DIAGONAL axis of the anatomy
Encode data along the SHORT axis of the anatomy
Both the DIAGONAL and SHORT axes
Encode data along the SHORT axis of the anatomy
Which gradient performs slice selection for coronal slices?
X gradient
Y gradient
Z gradient
Any combination of gradients
Y gradient
Which gradient performs phase encoding for coronal slices?
X gradient
Y gradient
Z gradient
Any combination of gradients
X gradient
When is the slice select gradient switched on during a spin echo pulse sequence?
During the rephasing pulse only
During the 90 and 180 degree pulses
During the excitation pulse only
It is always on during the scan
During the 90 and 180 degree pulses
To achieve thin slices, do we need a STEEP or SHALLOW slice select slope?
STEEP
SHALLOW
STEEP
To achieve THIN slices would we use a narrow or broad transmit bandwidth?
Narrow
Broad
Narrow
When is the phase encoding gradient switched on in a pulse sequence?
Before the 90 degree excitation pulse
Usually just before the application of the 180 degree rephasing pulse
Between TRs
During the spin echo
Usually just before the application of the 180 degree rephasing pulse
What does the slope of the frequency encoding gradient determine? (Select all that apply)
The size of the anatomy covered along the frequency encoding axis
The 180 degree rephasing pulse
The FOV
The size of the phase matrix
The size of the anatomy covered along the frequency encoding axis
The FOV
What is another term for the duration of the readout gradient?
X gradient
Sampling time
Z gradient
Window of opportunity
Sampling time
How often must we sample frequencies, according to the Nyquist Theorem?
Once per cycle
Twice per cycle
Three times per cycle
Less than once per cycle
Twice per cycle
What artifact occurs if we sample frequencies less than once per cycle?
Zipper
Cross talk
Cross excitation
Aliasing
Aliasing
What is the unit of K space?
Inches
Radians per meter
Radians per centimeter
Degrees
Radians per centimeter
T/F: The phase axis of K space is vertical and is centered in the middle of K space perpendicular to the frequency axis.
True
Which part of K space do steep phase gradients fill?
Outer lines of K space, positive only
Outer lines of K space, both positive and negative
Central lines of K space, positive only
Central lines of K space, both positive and negative
Outer lines of K space, both positive and negative
Which part of K space do shallow phase gradients fill?
Outer lines of K space, positive only
Outer lines of K space, both positive and negative
Central lines of K space, positive only
Central lines of K space, both positive and negative
Central lines of K space, both positive and negative
T/F: K space is not the image
True
Which gradient locates signal along the LONG axis of the anatomy?
Phase encoding gradient
Frequency encoding gradient
Slice select gradient
Isocenter gradient
Frequency encoding gradient
T/F: The scan time is the time to fill K space.
True
T/F: Data in K space are symmetrical.
True
What kind of information is contributed by data collected in the central lines of K space? (Select all that apply)
Resolution
Signal
Contrast
*weighting
Signal
Contrast
What kind of information is contributed by data collected in the outer lines of K space?
Resolution
Signal
Contrast
*weighting
Resolution
What controls the polarity of a gradient?
The steepness of the slice select gradient
The sharpness of the frequency readout
The direction of the current through the gradient coil
The strength of the main magnetic field
The direction of the current through the gradient coil
T/F: Phase encoding gradient positive fills the bottom half of K space.
False
Which gradient performs slice selection for sagital slices?
X gradient
Y gradient
Z gradient
Any combination of gradients
X gradient
What is another name for the frequency encoding gradient?
Phase encoding gradient
Short gradient
Readout gradient
Rephasing gradient
Readout gradient
Where are the data points collected by the system stored?
FFT
K space
Frequency domain
42.57 MHz
K space
During a typical spin echo sequence, there are three gradient applications. In chronological order they are:
Phase encoding, Slice select, Frequency encoding
Slice select, Phase encoding, Frequency encoding
Frequency encoding, Phase encoding, Slice select
Slice select, Frequency encoding, Phase encoding
Slice select, Phase encoding, Frequency encoding
Which gradient lies along the horizontal axis of a typical superconducting MRI system?
X gradient
Y gradient
Z gradient
W gradient
X gradient
If a 512 phase matrix is selected, which k-space lines are likely to be filled in a normal acquisition?
0 to 512
256 to -256
0 to -512
256, 0 to -255
256 to -256
Which of the following statements is true?
A data point contains frequency encoding information only
A data point contains phase encoding information only
A data point contains both phase and frequency information
A data point represents a specific pixel on the image
A data point contains both phase and frequency information
T/F: A thicker slice has a better SNR than a thinner slice.
True
Decreasing receive bandwidth by half increases the SNR by how much?
60%
40%
1/2
.22
40%
T/F: A fine matrix is one with a low number of frequency encodings and/or phase encodings, and results in a small number of pixels in the FOV.
False
Choose three factors that affect the SNR from the list below (there are three factors).
Magnetic field strength of the system
Proton density of the area under examination
The patient’s height and weight
Receive bandwidth
Magnetic field strength of the system
Proton density of the area under examination
Receive bandwidth
T/F: A long TE increases SNR and a short TE decreases SNR.
False
T/F: TR controls the amount of T2 weighting.
False
Choose the term that best describes “a unit volume of patient tissue” from the list below.
Pixel
Grayscale value
Voxel
Slice thickness
Voxel
Which of the following factors affect scan time during a sequential acquisition? (choose all that apply)
TR TE Phase Matrix NEX Frequency Matrix
TR
Phase Matrix
NEX
Which of the following factors affect voxel size (choose all that apply)?
Slice thickness
Number of pixels or matrix
Size of the flip angle
FOV
Slice thickness
Number of pixels or matrix
FOV
T/F: Square pixels ALWAYS provide better spatial resolution than rectangular pixels.
True
If we double the NEX, what does that do to our scan time?
Reduces the scan time by 1/2
Doubles the scan time
Reduces the scan time by 1.4
Increases the scan time by 1.4
Doubles the scan time
Decreasing the phase matrix does which of the following?
Decreases SNR
Increases spatial resolution
Makes the scan shorter
Has no effect on scanning
Makes the scan shorter
Of the following parameters, which would give the best spatial resolution?
256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX
256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX
512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX
None of the above would give good spatial resolution.
256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX
Of the following parameters, which would give the highest SNR?
256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX
256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX
512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX
None of the above.
256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX
Increasing the field strength increases SNR because:
The flip angle increases
The NMV increases in size because the high energy population of spins increases
The precessional frequency increases
The NMV increases in size because the low energy population of spins increases
The NMV increases in size because the low energy population of spins increases
Halving a square FOV reduces the SNR by:
1/2
1/4
3/4
1/8
3/4
Which of the following does NOT occur when the receive bandwidth is reduced?
SNR increases
Chemical shift artifact improves
Number of slices available decreases
TE increases
Chemical shift artifact improves
Doubling the number of signal averages changes the SNR by how much?
× 2
1/2
22
√2
√2
Which of these is a consequence of decreasing the TR from 2500 ms to 500 ms?
Scan time decreases
T1 weighting decreases
Spatial resolution decreases
Slice number available increases
Scan time decreases
Do we achieve greater SNR with a long or a short TR?
long
short
long
Pixel area = __ / matrix size.
SNR
Resolution
FOV
GNR
FOV
Which sequence is considered the gold standard for MR imaging?
SSFP
Spin Echo
Gradient Echo
Coherent Gradient Echo
Spin Echo
What is the approximate T1 relaxation time of CSF at 1T?
2000 ms
150 ms
500 ms
3000 ms
2000 ms
What is the approximate T1 relaxation time of fat at 1T?
2000 ms
200 ms
500 ms
3000 ms
200 ms
What do T1 images typically best demonstrate?
Anatomy
Pathology
Bright fluid
Everything
Anatomy
What does STIR stand for? Short ___ Inversion Recovery.
Tau
tau
TAU
When would we be most likely to use a STIR sequence?
CSF flow studies
MSK studies (i.e. knee, wrist)
Head or Spine studies (to look for periventricular lesions)
All studies must include a STIR sequence
MSK studies (i.e. knee, wrist)
T/F: FLAIR stands for Fluid Low Attenuation Inversion Recovery
False
When would we be most likely to use a FLAIR sequence?
MSK studies (i.e. knee, wrist)
Head or spine studies (to look for periventricular lesions)
All studies must include a FLAIR sequence
To image the great vessels
Head or spine studies (to look for periventricular lesions)
How is time reduced in fast spin echo? (Choose all that apply)
The operator must prescribe fewer slices
Use a turbo factor
Use thinner slices
Use an echo train
Use a turbo factor
Use an echo train
What artifact can occur as a result of using long echo trains?
Cross talk
Truncation
Image Blurring
Aliasing
Image Blurring
An inversion recovery pulse sequence begins with which of the following?
90 degree RF pulse
180 degree inverting pulse
180 rephasing pulse
Gradient pulse (variable flip angle)
180 degree inverting pulse
Which Fast Inversion Recovery sequence(s) do we often use?
STIR
SSFP
FLAIR
Incoherent Gradient Echo
STIR
FLAIR
What is Double IR prep used to accomplish?
Used to null blood for cardiac imaging
Flips the NMV back to zero
Imaging large patients
FSE sequences
Used to null blood for cardiac imaging
A coherent gradient echo sequence samples which of the following?
FID Only
Stimulated Echo Only
Both the FID and Stimulated Echo
T2 Information Only
Both the FID and Stimulated Echo
T/F: During EPI all the lines of K space are filled during one repetition.
True
How is K space filled in Fast Gradient Echo Sequences? (choose all that apply)
Elliptical filling
Centric filling
Keyhole filling
Outside to inside
Centric filling
Keyhole filling
In which of the following sequences is all the transverse magnetization rewound at the end of each TR period?
Coherent gradient echo
Incoherent gradient echo
EPI
Coherent gradient echo
Which of the following statements is true in an incoherent gradient echo sequence?
Residual transverse magnetization has the same phase as the magnetization most recently created
The flip angle is always 10°
The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value
It is not a steady state sequence
The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value
What type of echoes are sampled during SS-FSE?
Spin echoes
Gradient echoes
Incoherent Gradient echoes
Spin echoes
What are the advantages of propeller K Space filling?
Better detail
Low SNR but high resolution
Bright signal
Rapid imaging, increased SNR and CNR, reduced motion artifact.
Rapid imaging, increased SNR and CNR, reduced motion artifact.
T/F: Using a long echo train decreases the SAR.
False
T/F: STIR sequences should NOT be used in conjunction with contrast enhancement.
True
T/F: Spin echo pulse sequences are classified according to whether the residual transverse magnetization is in phase (coherent) or out of phase (incoherent).
False
SSFP sequences usually produce images that are ___ weighted.
T1
T2
T2*
T1 or T2*
T2
T/F: Parallel imaging is usually used to increase resolution or decrease scan time.
True
Which artifact is produced as a result of motion of flowing nuclei?
Zipper effect
Aliasing
Phase ghosting
Truncation
Phase ghosting
Which type of motion can we compensate for in MRI?
First order laminar flow
Second order motion acceleration
Third order motion jerk
All of those listed can be compensated for
First order laminar flow
T/F: TOF phenomenon results in a dark vessel.
True
Which of the following effects does TOF depend on? (Select all that apply)
Velocity of flow
TE
Slice Thickness
TR
Velocity of flow
TE
Slice Thickness
Choose the two main uses of spatial pre-saturation from the list below. (Select all that apply)
Chemical Pre-saturation
STIR
FLAIR
SPIR
Chemical Pre-saturation
SPIR
T/F: Counter current flow occurs when flowing nuclei are traveling in the same direction as slice selection.
False
Which of the following is/are result(s) of time of flight? (Select all that apply)
Flow-related enhancement
Entry slice phenomenon
High velocity signal void
Zipper effect
Flow-related enhancement
High velocity signal void
In a dual echo sequence, which of the following combinations would result in reduced flow artifact in the second echo?
TE 20 and 50 ms
TE 20 and 70 ms
TE 40 and 80 ms
TE 40 and 95 ms
TE 40 and 80 ms
What is the chemical shift at 1.5 T?
2.2 Hz
22 Hz
220 Hz
220KHz
220Hz
T/F: STIR is most useful in post contrast imaging.
False
T/F: Even echo rephasing reduces intra-voxel dephasing.
True
T/F: Intra-voxel dephasing results in an increase in total signal amplitude from the voxel.
False
Stationary nuclei always receive both excitation and rephasing pulses, but flowing nuclei present in the slice for the excitation may have exited the slice before rephasing. This is called ______________.
Time of Flight Phenomenon
Entry Slice Phenomenon
Intra-Voxel Dephasing
Turbulent Flow Effects
Time of Flight Phenomenon
T/F: As velocity of flow decreases, the time of flight effect decreases.
True
T/F: Another term for time of flight is inflow effect.
False
Determine which of the following parameters would result in the most entry slice phenomenon (i.e. entry slice phenomenon would increase compared to the other options).
Slice 1 of 20, 3000 TR, .7 mm slice thickness
Slice 1 out of 20, 400 TR, 1.2 mm slice thickness
Slice 10 out of 20, 3000 TR, 1.2 mm slice thickness
Slice 10 out of 20, 400 TR, .7 mm slice thickness
Slice 1 of 20, 3000 TR, .7 mm slice thickness
T/F: Flow affects image quality.
True
The frequency difference between fat and water is called ___________ and can be used to specifically null the signal from either fat or water.
Chemical Pre-Saturation
Chemical Shift
Precessional Frequency
Even Echo Rephasing
Chemical Shift
T/F: Any tissue can be nulled as long as an RF pulse matching its precessional frequency is applied to the imaging volume before excitation.
True
T/F: Pre-saturation techniques increase the RF deposition to the patient.
True
What is another term for phase ghosting?
Phase wrap
Phase mismapping
Chemical misregistraion
Aliasing
Phase mismapping
What is another term for phase ghosting?
Phase wrap
Phase mismapping
Chemical misregistraion
Aliasing
Phase mismapping
In which direction does phase ghosting occur? (Choose all applicable)
Phase Axis
Frequency Axis
Slice Select Axis
Anterior to Posterior
Phase Axis
Which of the following are methods of reducing phase ghosting? (Choose all that apply)
Using respiratory compensation techniques
Decrease the TE
Carefully explain the procedure to the patient
Swap phase and frequency
Use pre-saturation pulses
Use “no phase wrap” software
Using respiratory compensation techniques
Carefully explain the procedure to the patient
Swap phase and frequency
Use pre-saturation pulses
In which direction does aliasing occur? (Choose all that apply)
Phase Axis
Frequency Axis
Slice Select Axis
Anterior to Posterior
Phase Axis
Frequency Axis
Which of the following is a remedy for aliasing?
Decreasing the slice thickness
Decreasing the size of the FOV
Decreasing the TE
Using “no phase wrap” software
Using “no phase wrap” software
Which of the following best describes the appearance of chemical shift artifact on an image?
Extra information wraps into the image
The cancellation of fat and water signals when they are out of phase.
Banding artifact at the interfaces of high and low signal.
Produces a dark edge at the interface between fat and water.
Produces a dark edge at the interface between fat and water.
In which direction does chemical shift artifact occur? (Choose all that apply)
Phase Axis
Frequency Axis
Slice Select Axis
Anterior to Posterior
Frequency Axis
What unit is used to express the amount of chemical shift?
MHz
Hz
ppm
gyromagnetic ratio
ppm
What is another name for a truncation artifact in a sagital cervical spine?
Truncation
Gyromagnetic Artifact
Gibbs
Faraday
Gibbs
How can we reduce truncation?
Increase the TE
Increase the TR
Increase the number of phase encoding steps
Increase the number of frequency encoding steps
Increase the number of phase encoding steps
In which direction does truncation occur? (Choose all that apply)
Phase Axis
Frequency Axis
Slice Select Axis
Anterior to Posterior
Phase Axis
Which best describes the appearance of a zipper artifact?
Distortion of the image together with large signal voids.
Anatomy folded into the FOV
A dense line on the image at a specific point.
Tissues return a high signal intensity
A dense line on the image at a specific point.
Which best describes the appearance of a zipper artifact?
Distortion of the image together with large signal voids.
Anatomy folded into the FOV
A dense line on the image at a specific point.
Tissues return a high signal intensity
A dense line on the image at a specific point.
Which of the following is a possible cause of shading artifact?
A hemorrhage
A leak in the RF shielding of the scan room
Spin echo sequences
Inhomogeneities in the main magnetic field
Inhomogeneities in the main magnetic field
Which of the following best describes Moire artifact?
Black and white banding artifact on the edge of the FOV
Fat and water are out of phase and their signals cancel each other out.
Different chemical environments of fat and water produce a dark edge at the interface between fat and water.
Anatomy from outside the FOV are wrapped into the image.
Black and white banding artifact on the edge of the FOV
T/F: To reduce chemical shift artifact, ALWAYS use the widest receive bandwidth in keeping with good SNR and the smallest FOV possible.
True
T/F: To reduce chemical shift artifact, ALWAYS use the widest receive bandwidth in keeping with good SNR and the smallest FOV possible.
True
In spin echo sequences using a pre-saturation pulse, what would persistent bright signal within the vessel indicate?
Slow Flowing Blood
Fast Flowing Blood
Blood Clot
Vascular Occlusion
Slow Flowing Blood
Blood Clot
Vascular Occlusion
Which of the following best describes what the “P” wave represents?
Atrial Systole (Contraction)
Ventricular Systole
Ventricular Diastole
None of the above
Atrial Systole (Contraction)
Which of the following best describes what the “QRS” complex represents?
Atrial Systole (Contraction)
Ventricular Systole
Ventricular Diastole (Relaxation)
None of the above
Ventricular Systole
Which of the following best describes what the “T” wave represents?
Atrial Systole (Contraction)
Ventricular Systole
Ventricular Diastole (Relaxation)
None of the above
Ventricular Diastole (Relaxation)
Which of the following sequence(s)/technique(s) can be used to make vessels appear bright?
Gradient Echo Imaging
Gradient Moment Rephasing
Contrast Enhancement
All of the above
All of the above
Which of the following is used to trigger each pulse sequence when using ECG gating?
P wave
Q wave
R wave
S wave
R wave
How much does a typical patient’s heart rate vary during an exam?
10- 20 %
20- 30%
40- 50%
60- 70%
10- 20 %
If the R to R interval is 500 ms, the trigger window is 10%, and the trigger delay is 50 ms, what is the time available to acquire data?
310 ms
400 ms
460 ms
500 ms
400 ms
If the R to R interval is 500 ms, the trigger window is 10%, and the trigger delay is 50 ms, what is the time available to acquire data?
310 ms
400 ms
460 ms
500 ms
400 ms
What determines the length of the R to R interval?
The technologist performing the exam
The radiologist who establishes the protocol
The patient’s heart rate
The type of sequence
The patient’s heart rate
What is the waiting period before each R wave called?
Trigger Window
Trigger Delay
R to R Interval
Available Imaging Time
Trigger Window
T/F: ECG gating is prospective.
True
When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by:
2D Time of Flight MRA
3D Time of Flight MRA
3D Phase Contrast MRA
All of the Above
3D Time of Flight MRA
When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by:
2D Time of Flight MRA
3D Time of Flight MRA
3D Phase Contrast MRA
All of the Above
3D Time of Flight MRA
MRA techniques include all of the following EXCEPT:
TOF-MRA
PC-MRA
CE-MRA
CT-MRA
CT-MRA
Which of the following does NOT reduce flow motion artifact?
SAT
ECG gating
GMN
Subtraction
Subtraction
Which of the following can be used to improve coverage and at the same time maintain the signal from blood flowing within the larger volume?
MC-TOF
PC-MRA
MOTSA
Phase images
MOTSA
The vascular signal, produced on time of flight MRA (TOF-MRA), relies on:
MOTA
PC
Flow related enhancement
Velocity-induced phase shifts
Flow related enhancement
The vascular signal, produced on PC-MRA, relies on:
MOTA
PC
Flow related enhancement
Velocity-induced phase shifts
Velocity-induced phase shifts
Contrast enhanced MRAs are acquired with all of the following EXCEPT:
Test bolus
Bolus tracking
VENC settings
Fluoro triggering
VENC settings
Contrast enhanced MRAs are acquired with all of the following EXCEPT:
Test bolus
Bolus tracking
VENC settings
Fluoro triggering
VENC settings
Multiphase images, acquired with additional modulation of magnetization, are known as:
TOF-MRA
PC-MRA
VENC
SPAMM
SPAMM
What is the available imaging time using these parameters? R to R 800 ms, trigger window 10%, delay after trigger 4 ms.
688 ms
700 ms
716 ms
800 ms
716 ms
When using MRA to evaluate peripheral vascular flow, such as that within the arteries of the legs, saturation pulses are:
Placed superior to the acquired slices
Placed in the acquired slices
Placed inferior to the acquired slices
Not necessary
Placed inferior to the acquired slices
When using MRA to evaluate extracranial vascular flow, such as that within common carotid arteries, a recommended technique is:
2D time of flight MRA
3D time of flight MRA
3D phase contrast MRA
All of the above
2D time of flight MRA
When using MRA to evaluate extracranial vascular flow, such as that within common carotid arteries, a recommended technique is:
2D time of flight MRA
3D time of flight MRA
3D phase contrast MRA
All of the above
2D time of flight MRA
Magnetic field strength can be expressed in units of Tesla (T) or gauss (G), where:
1 T = 1 G
- 5 T = 1500 G
- 0 T = 0.3 G
1 T = 10 000 G
1 T = 10 000 G
The homogeneity of a magnetic field is expressed in units of:
ppm (parts per million)
T (Tesla)
G (gauss)
MHz (megaHertz)
ppm (parts per million)
The homogeneity of a magnetic field is expressed in units of:
ppm (parts per million)
T (Tesla)
G (gauss)
MHz (megaHertz)
ppm (parts per million)
Gradient strength is expressed in units of all of the following EXCEPT:
w/kg
mT/m
G/cm
T/m/s
w/kg
Gradient strength is expressed in units of all of the following EXCEPT:
w/kg
mT/m
G/cm
T/m/s
w/kg
Passive magnetic shielding can be accomplished by lining the scan room walls with:
Copper
Lead
Steel
Shim plates
Steel
Fourier transform (FT) is a mathematical process that is used to convert MR signal from a FID into a spectrum. FT occurs in the:
Image processor
Array processor
RF coil
Gradient amplifier
Array processor
What rule determines the direction of current flow through a coil, and the direction of the magnetic field that the current produces?
The size of the magnetic field
Right hand thumb rule
MRI Fringe Field Rule
Whether you are using an open or closed configuration
Right hand thumb rule
What is the maximum field strength allowed for clinical imaging of adults in the USA?
3 T
4 T
8 T
10 T
8 T
T/F: The purpose of magnetic field shimming is to reduce the size of the fringe field.
False
What is the most common material used to make permanent magnets?
Titanium
Helium
Iron
Alnico
Alnico
Ohm’s law states:
B = k (l)
V = I (R)
B = H (1 x)
1 T = 10 kG
V = I (R)
T/F: The law of electromagnetic induction indicates that whenever a charge particle such as an electron exhibits motion, a corresponding magnetic field is induced.
True
Which cryogen is commonly used to super cool wires in MRI?
Liquid helium
Niobium
Alnico
Hydrogen
Liquid helium
Which material is most commonly used to make superconducting wires?
Liquid helium
Niobium-titanium alloy
Alnico
Hydrogen
Niobium-titanium alloy
Why do we use shimming?
To apply a magnetic field
To make the field even or homogenous
To make the magnetic field smaller
To induce a current
To make the field even or homogenous
Select all of the following that determine the strength of an electromagnet:
The amount of current passed through the windings
The number of windings in the coil
The distance or spacing between the windings
The diameter of the wire used in the windings
All of the above
In a typical superconducting magnet, the direction of the magnetic field is:
Vertical
Horizontal
Around the flux lines
Hard to measure
Horizontal
T/F: The SNR is enhanced when using local coils.
True
T/F: The SNR is enhanced when using local coils.
True
What does BOLD stand for?
Blood oxygenation level dependent
Blood oxygen line developed
Body oriented level dependent
Type of CT scanning
Blood oxygenation level dependent
Functional imaging techniques include which of the following (check all that apply)?
DWI
fMRI
Spectroscopy
Perfusion imaging
All of the above
T/F: Functional imaging techniques allow MRI to be used to assess function and physiology as opposed to merely conventional structural imaging.
True
What term is used to describe the net displacement of diffusion spins across a tissue?
SWI
fMRI
ADC
MRS
ADC
What is the extrinsic parameter that controls the amount of diffusion seen in an image?
TR
TE
flip angle
b factor
b factor
What signal intensity is an area of abnormality likely to have on an ADC map?
Hypointense
Hyperintense
Isointense
Hypointense
What signal intensity is an area of abnormality likely to have on a trace image?
Hypointense
Hyperintense
Isointense
Hyperintense
T/F: Perfusion is the regional blood flow in tissues and is defined as the volume of blood that flows into one gram of tissue.
True
Which of the following best describes a use for MR Spectroscopy (MRS)?
To show ankle anatomy
To aid in brain tumor staging
To demonstrate perfusion
To aid in brain tumor staging
T/F: Interventional MRI includes performing biopsies in the MR suite.
True
Chemical shift is measured in which of the following units?
mm/s
ppm
T/m
G/cm
ppm
T/F: Perfusion is measured using MRI by tagging the fat in arterial blood during image acquisition.
False
The anatomy of white matter tracts can be mapped using strong multi-directional gradients in which of the following?
SWI
diffusion tensor imaging (DTI)
continuous arterial spin labeling (CASL)
CBV
diffusion tensor imaging (DTI)
T/F: MR microscopy (MRM) is useful as a research tool when studying detail in a very small area of tissue.
True
T/F: MR microscopy (MRM) is useful as a research tool when studying detail in a very small area of tissue.
True
T/F: Gadolinium chelates are ferromagnetic.
False
After gadolinium administration, it is recommended that which images are acquired?
One T1 weighted image
One T2 weighted image
Multiple T1 weighted images
Multiple T2 weighted images
Multiple T1 weighted images
Enhanced MR images are evaluated for sensitivity and specificity, where sensitivity is ________ and specificity is ________.
The ability to detect the lesion/the ability to classify the lesion
The ability to classify the lesion/the ability to detect the lesion
TE used to evaluate the lesion/TR used to evaluate the lesion
TR used to evaluate the lesion/TE used to evaluate the lesion
The ability to detect the lesion/the ability to classify the lesion
T/F: All gadolinium contrast agents have the same ‘relaxivity’.
False
Choose all of the following that enhancement agents can be useful in detecting.
Infection
Tumors
Infarction
Inflammation
All of the above
On a T1 weighted pre-contrast image, fat appears _____ and water appears _____.
Bright, Dark
Bright, Bright
Dark, Bright
Dark, Dark
Bright, Dark
T/F: Scar tissue enhances in the lumbar spine shortly after the injection of contrast.
True
T/F: Scar tissue enhances in the lumbar spine shortly after the injection of contrast.
True
Which sequence would be used to best visualize metastatic lesions in the bone?
FLAIR with contrast
Fat saturation techniques with contrast
T2 weighted sequences
Non-contrast imaging
Fat saturation techniques with contrast
T/F: Gadolinium cannot cross the intact blood-brain barrier (BBB).
True
Gadolinium element is ________ and gadolinium chelate contrast media is ________.
Ferromagnetic/paramagnetic
Ferromagnetic/ferromagnetic
Paramagnetic/ferromagnetic
Paramagnetic/paramagnetic
Ferromagnetic/paramagnetic
T/F: When using gadolinium, the T1 relaxation time of the water is reduced so enhancing lesions (such as tumors associated with free water) appear bright on a T1 weighted image.
True
Select all of the following that were discussed as possible MR contrast agents in the text.
Gadolinium
Blueberry juice
Mango juice
Dilute barium solutions
All of the above
