Nice images Linh,
I think there is real flow in this ICA,
The pulse Doppler waveform is low resistance which indicates that there is indeed an outlet for the flow to go to. If there is an occlusion of the ICA I would expect a high resistance waveform in the stump immediately proximal to the occlusion,
The peak systolic velocity is low indicating trickle flow only.
So with good evidence of trickle flow in the ICA it is time to have an assessment with some form of angiography (conventional, CTA or MRA) and a vascular surgical opinion.
Good case Linh.
Let me know what the angiogram shows.
Steve