Non-Invasive Testing Procedures Flashcards

Which waveform characteristic is MOST associated with a proximal arterial obstruction when assessing a distal vessel?

Answer: Monophasic dampened waveform with loss of dicrotic notch

A proximal obstruction dampens the distal waveform, producing a monophasic pattern with loss of the dicrotic notch and reduced pulsatility.

During a lower extremity venous duplex exam, which finding is MOST diagnostic of acute deep vein thrombosis?

Answer: Anechoic lumen with absence of spontaneous flow and non-compressibility

Acute DVT classically presents as a non-compressible vein with anechoic (echo-free) intraluminal thrombus and absent spontaneous flow.

A patient's ankle-brachial index (ABI) is 0.55. Which clinical category does this fall into?

Answer: Moderate peripheral arterial disease

An ABI of 0.41–0.70 indicates moderate PAD, associated with claudication symptoms.

What is the significance of a post-exercise ABI that DECREASES by more than 20% from resting values?

Answer: Evidence of hemodynamically significant arterial stenosis

A post-exercise ABI drop >20% confirms hemodynamically significant PAD even when resting ABI is borderline.

Which parameter is used to calculate the Resistive Index (RI) in renal duplex ultrasound?

Answer: (PSV − EDV) / PSV

RI = (PSV − EDV) / PSV; values >0.70 suggest increased downstream resistance or intrinsic renal disease.

During carotid duplex imaging, an ICA/CCA PSV ratio of 4.2 correlates with which degree of stenosis?

Answer: ≥80%

An ICA/CCA ratio ≥4.0 is consistent with ≥80% stenosis per Society of Radiologists in Ultrasound (SRU) criteria.

What physiologic principle explains why plethysmographic waveforms become flattened and prolonged with arterial occlusive disease?

Answer: Reduced pulse pressure and delayed pressure transmission distal to the stenosis

Arterial stenosis reduces and delays the pressure wave, resulting in flattened, prolonged plethysmographic waveforms distally.