Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
29 Cards in this Set
- Front
- Back
transverse images of knee are being acquired with a pulse sequence which allows for flow comp. which direction is flow comp. best applied to reduce motion artifact from popliteal artery?
|
Slice direction |
|
Spectral fat sat. increases SAR..T or F
|
True
|
|
Motion artifact techniques are not generally used in MRA.. T or F?
|
False |
|
If gradient moment nulling is applied only along the slice direction of a transverse set of brain images, which physical gradient must use extra pulses..? |
Z-gradient
|
|
When gradient moment nulling is added to a pulse sequence and all other parameters are unchanged the..? -Min. echo time may be increased -Scan time may be increased -Size of anatomy may be decreased -SAR of sequence may be increased |
Min. echo time may be increased
|
|
In which direction must the artifact from motion appear in the image..?
|
Phase direction
|
|
Which statement is false regarding gradient moment nulling..? -uses extra gradient pulses to rephase the signal from moving protons -tends to be effective reducing CSF pulsation artifacts -only rephases moving protons not stationary protons. -vessels generally appear bright. |
Only rephases moving protons
|
|
Which of the following has no effect upon scan time. -respiratory triggering -respiratory gating -respiratory compensation |
Respiratory comp.
|
|
Respiratory compensation does what..?
|
Reorders the filling of the rawdata |
|
__ mag. |
Transverse |
|
Which of the gradients is not balanced for phase prior to collecting echo..?
|
phase |
|
If the thickness of a single sat region is doubled, the SAR will..?
|
Be unaffected
|
|
which of the following techniques may shorten the scan time..? -pulse gating -respiratory gating -spectral fat supp. -ECG triggering |
ECG triggering
|
|
what are some of the reasons gradient moment nulling is not typically used on T1- weighted images..?
|
-most moving fluids have low intensity -important to maintain short echo times -multiple signal averages are used |
|
PT 7
|
|
|
gradient echo sequences are rarely used for delineating tumors because..?
|
they do not show true T2 contrast
|
|
Volume- which gradients are responsible for phase encoding operation of dividing the volume into sagittal slices..?
|
X and Y gradients |
|
PT8
|
|
|
An acute artifact appears __ on the DW image and __ on the ADC image. |
Bright, Dark |
|
Which technique provides the best stationary tissue suppression? |
PCA |
|
the __ of the blood is responsible for the bright signal in TOF. |
flow |
|
which of the following results from reducing the volume of vessels to which MIP is applied..? -reduces vessel overlap -increases vessel contrast -reduces processing time |
all |
|
When RF is repeatedly transmitted into the same tissues what happens to the nmv amplitude..? increase or decrease.. |
Decreases |
|
Relevant B0 values are in the range of..? |
500 to 1200 s/mm |
|
An ADC image: |
Will show an acute infarct as hypo intense to healthy surrounding tissue. |
|
What would happen to the background tissue in a 3D TOF if TR is shortened..? RF pulse being repeated more rapidly) |
Stationary tissue would appear darker |
|
in perfusion imaging what happens to signal intensity as contrast passes..? |
Gets darker on the T2 image pg.37 great discription |
|
The degree of stenosis may be overestimated with TOF because dephase due to __ flow __ to the stenosis causing reduction in signal. |
Turbulent, distal |
|
In spectroscopy __ is not required. -shimming -MIPing -water suppression |
MIPing |