Unit 14: Diagnostic criteria Flashcards
What 5 things does a carotid duplex exam show?
- Presence of carotid disease
- Location of disease
- Severity of disease
- Progression of disease
- Other pathology
What should be used in the exam interpretation?
Scientific proven criteria.
What type of criteria does the IAC accept?
Supports criteria from literature OR well-proven internal developed criteria.
What is the PSV in a normal ICA?
<125 cm/s
What is the psv ratio that indicates less than 50% diameter reduction?
2.0
How is the EDV throughout the carotid and vertebral arteries?
Generally above zero
What does long duration diastolic reversed flow bilaterally indicate?
aortic regurgitation.
If abnormal waveforms are seen bilaterally what is usually the cause?
A cardiac source.
In the diagnostic criteria of U of W, how is it created?
Strict 60 degree angle.
In the diagnostic criteria of U of W, what does it ONLY apply to?
The first 3 cm of the ICA
In the diagnostic criteria of U of W, how can you reduce the variability in an exam comparison?
Use the same angle and sa,e steer direction as previous exam.
In the diagnostic criteria of U of W, what is needed to clearly diagnose a signifcant change?
A change from one range (grade) to another.
What are some common errors affecting velocity measurements?
- Angle
- Highest velocity not found
- Labeling the velocity in the wrong vessel.
- Reporting the velocity found as highest even though a calcific shadow may obscure the highest velocity (report limitations)
- Overgain
What must there be in order to identify an occlusion?
- Must show vessel clearly.
- Must show no flow using sample volume in appropriate angle, gain, scale.
- Must never call occlusion based on color alone.
What does no diastolic velocity in the CCA, ICA and the VERT indicate?
It indicates probable distal occlusion but might be very high grade significant distal stenosis.
No EDV in CCA indicates?
Probable ICA occlusion.
No EDV in ICA indicates?
Probable intracranial ICA occlusion.
No EDV in the vertebral indicates?
Probable distal occlusion.
What is the exception to ICA velocity criteria?
Compensatory flow.
What can an occlusion or a very tight stenosis cause?
An increased velocities on the contralateral side if it is a primary source of collateral flow.
What can compensatory flow exaggerate?
The grade of stenosis.
How can you confirm compensatory flow?
- First look to see if the CCA velocities are noticeably higher on the side opposite of the occlusion.
- Use ratio and image measurements to confirm that compensatory flow is exaggerating the velocities.
- The ratio will indicate a lower grade than the velocities in the criteria.
T/F:
Cannot discern stenosis with certainty between spinal processes.
True
When would an occlusion be probable in the vertebrals?
If venous flow at the same location is present, but no arterial flow.
