Chapter 8 Flashcards
When using MRA to evaluate intracranial vascularity, flow within smaller vessels can best be demonstrated by:
3D Time of Flight MRA
What determines the length of the R to R interval?
The patient’s heart rate
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?
400 ms
What is the waiting period after each R wave called?
Trigger Delay
Which of the following best describes what the “P” wave represents?
Atrial Systole (Contraction)
What is the available imaging time using these parameters? R to R 800 ms, trigger window 10%, delay after trigger 4 ms.
716 ms
800- 80 - 4 = 716 ms
The vascular signal, produced on PC-MRA, relies on:
Velocity-induced phase shifts
How much does a typical patient’s heart rate vary during an exam?
10- 20 %
The vascular signal, produced on time of flight MRA (TOF-MRA), relies on:
Flow related enhancement
Which of the following does NOT reduce flow motion artifact?
Subtraction
Which of the following best describes what the “QRS” complex represents?
Ventricular Systole
Generally, 3D TOF-MRA acquisitions are optimal for high resolution, for the evaluation of:
Smaller vessels with high velocity blood flow (intracranial vessels associated with the Circle of Willis, COW)
The signal from flowing blood within vessels in MRI and MRA relies on:
First order motion
In spin echo sequences using a pre-saturation pulse, what would persistent bright signal within the vessel indicate?
Vascular Occlusion
Blood Clot
Slow Flowing Blood
What is the waiting period before each R wave called?
Trigger Window
Which of the following sequence(s)/techniques(s) can be used to produce images where vessels appear dark?
The Application of Pre-Sat Pulses
Spin Echo Acquisitions
When using MRA to evaluate extracranial vascular flow, such as that within common carotid arteries, a recommended technique is:
2D time of flight MRA
Which of the following best describes what the “T” wave represents?
Ventricular Diastole (Relaxation)
Which of the following is used to trigger each pulse sequence when using ECG gating?
R wave
ECG gating is prospective. (T or F)
true
Prospective- the scan is time to and triggered from the beats of the heart during acquisition
Multiphase images, acquired with additional modulation of magnetization, are known as:
SPAMM
Contrast enhanced MRAs are acquired with all of the following EXCEPT:
VENC settings
Which of the following sequence(s)/technique(s) can be used to make vessels appear bright?
Contrast Enhancement
Gradient Moment Rephasing
Gradient Echo Imaging
(all of the above)
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?
MOTSA
MRA techniques include all of the following EXCEPT:
CT-MRA
When using MRA to evaluate peripheral vascular flow, such as that within the arteries of the legs, saturation pulses are:
Placed inferior to the acquired slices
Saturation pulses can be used to suppress the signal from venous blood to allow for better visualization of arterial flow.
How much do most patient’s heart rate vary during the scan?
10-20%
What position in the chest does the heart lie?
double oblique
where is base of heart
located superiorally
where is apex of heart
located inferiorally
where is atrial septum
separates atria
where is ventricular septum
separates ventricles
prospective gating
scan is triggered from beats of heart, uses R-R
retrospective gating
after scan is completed
MOTSA
maintain signal and improve coverage w large volume
MIP
projects maximum intensity
SSD
surface is presented on the reformated data as though illiminated by directional light source
SPAMM
spatial modulation of magnet
3D TOF MRA
high resolution, evaluation of smaller vessles w high velocity blood flow (COW)
2D TOF MRA
slow velocity w large FOV (carotids, venous)
vessel appearance spin echo with pre-saturation
black blood
vessel appearance gradient echo with GMN
bright blood
vessel appearance peristant signal within a vessel lumen after the application of a SAT pulses
slow flow. Ex (blood clot or vascular occlusion
parameters used in gating : T1 weighting
1 R-R interval, short TE
parameters used in gating : PD weighting
2-3 R-R intervals, short TE
parameters used in gating : T2 weighting
2-3 R-R intervals, long TE
What is the equation for available imaging time?
=R-R interval - (trigger window + trigger delay)
Which are options for the optimization of scan timing
bolus tracking: tracker pulse measures signal from the lumen
fluoro triggering: the operator witnesses the arrival of the contrast
test bolus: small injection made to determine the exact time to begin scanning
trigger window
waiting time before each R-R wave
trigger delay
waiting period after each R-R wave
Digital Subtraction MRA
2 T2 data sets, one during systolic and one during diastolic (fresh blood imaging)
TOF MRA
enhancment related to the flow of blood
PC MRA
signal relies on velocity-induced phase shifts
contrast enhanced MRA
T1 3D gradient echo following by gad and dynamic imaging
Which of the following statements concerning the safety of gating is correct?
Do not used frayed or splitting cables
Do not loop or cross-over cables
Make sure the cables do not touch the patient
Place pads between the cables and the patient
Calculate the correct dosage of gadolinium contrast for a 160-pound patient with normal renal function.
15 mL
165/2.2=75kg*0.2=15mL
ECG
electrodes and wires placed on pts chest
peripheral gating
placed on pts finger
black blood
SE w pre-sats, inversion recovery
bright blood
GRE, GMN, contrast enhancement
