Which of the following is NOT a duplex indication of a totally occluded ICA?

The key to understanding this question lies in the nature of duplex ultrasound findings that suggest the presence of a totally occluded internal carotid artery (ICA).

The presence of greatly increased end-diastolic velocities in the common carotid artery (CCA) is indicative of collateral circulation or other altered hemodynamics rather than a direct finding related to the occluded ICA. In the case of a totally occluded ICA, one would typically expect to see a lack of normal flow patterns because the artery is obstructed and unable to allow blood to flow through it. Thus, increased end-diastolic velocities in the CCA would not be consistent with a diagnosis of total occlusion in the ICA; instead, this finding may suggest other vascular dynamics at play.

In contrast, the other options reflect common observations that can indicate complete occlusion of the ICA. The absence of diastolic flow in the CCA would be expected as the blood would not be flowing correctly from the common carotid into the occluded ICA. The presence of heterogeneous echoes filling the ICA lumen suggests the lumen is indeed obstructed and could be filled with debris or thrombus, a common finding in occluded arteries. Lastly, the lack of Doppler or color flow detectable within the ICA