Abdominal Vascular Duplex Exams Flashcards

In abdominal aortic duplex imaging, which characteristic best defines an aortic dissection on B-mode and color Doppler?

Answer: An intimal flap creating true and false lumens with differing flow characteristics

An aortic dissection produces an intimal flap visible on B-mode that separates the vessel into two lumens, often with different flow velocities and directions on color Doppler.

When performing mesenteric duplex scanning, which fasting PSV in the SMA most reliably identifies ≥70% stenosis?

Answer: ≥275 cm/s

A fasting SMA PSV of 275 cm/s or greater has been validated as the threshold for detecting ≥70% stenosis in most published duplex criteria.

During hepatic duplex evaluation after liver transplantation, which finding most urgently suggests hepatic artery thrombosis?

Answer: Absent hepatic artery Doppler signal with no intrahepatic arterial flow

Complete absence of hepatic artery signal is the most critical finding, as hepatic artery thrombosis is a surgical emergency threatening graft survival.

Color Doppler aliasing during an abdominal duplex exam most commonly occurs because:

Answer: The Doppler shift frequency exceeds half the pulse repetition frequency (Nyquist limit)

Aliasing occurs when detected Doppler frequencies exceed the Nyquist limit (PRF/2), causing the system to misrepresent flow direction and velocity.

Which duplex protocol modification is most appropriate when attempting to image the renal arteries in an obese patient with a technically difficult examination?

Answer: Use a lower frequency curved transducer, optimize depth and focus, and try decubitus or posterior flank approaches

Lower frequency transducers provide better penetration in obese patients, and alternative scan windows such as the flank approach can bypass bowel gas and adipose tissue.

In portal vein duplex evaluation, normal portal vein flow is described as hepatopetal with a velocity of approximately:

Answer: 16–40 cm/s with mild respiratory phasicity

Normal portal vein flow is directed toward the liver (hepatopetal) at 16–40 cm/s, with slight variation related to respiration and cardiac pulsatility.

Which abdominal duplex finding in a patient with known atherosclerosis suggests the presence of chronic mesenteric ischemia rather than acute mesenteric ischemia?

Answer: Collateral vessel formation with retrograde filling of the SMA via the arc of Riolan or marginal artery

Chronic ischemia allows time for collateral development such as the arc of Riolan; acute occlusion does not allow collateral formation and presents with absent flow and no collaterals.