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Carotid doppler radiology8/13/2023 Therefore, we ask the question of whether the imaging findings of A1 are related to the hemodynamics of this region during ICAS? To answer this, this study used a transcranial Doppler (TCD) to detect the hemodynamics of major intracranial and extracranial vessels, including adjacent vessels around the A1, and compared them with the CTA examination. Based on the experience of previous studies, we might attribute the asymmetry of the A1 branch bilaterally in ICAS to normal variation however, according to the anatomy of the Circle of Willis, A1 may be the hemodynamic intersection of primary and secondary collateral circulation compensation after unilateral ICAS. The shunt from the anterior communicating artery (AcoA) to the A1 of the anterior cerebral artery (ACA) is a crucial primary channel of collateral circulation. Owing to intracranial blood flow self-regulation, the ipsilateral hypoperfusion in cases of unilateral ICAS causes a change in the intracranial hemodynamics that facilitates collateral circulation ( Henderson et al., 2000). It is well known that ICAS is a common neurological disease that accounts for approximately 10% of CVAs ( Abbott et al., 2007). A variation in the circle of Willis is more common in patients that have suffered a cerebrovascular accident (CVA) ( De Caro et al., 2021), and the abnormal development of A1 may be a risk factor for ischemic symptoms in patients with ICAS ( Van Seeters et al., 2015). ![]() Previous studies have shown many possible variations in the circle of Willis, with an abnormal development of the A1 accounting for 6.7% of these ( Krabbe-Hartkamp et al., 1998). The circle of Willis is an important channel for the compensation of intracranial blood flow in ICAS ( Hartkamp et al., 1999). In our clinical practice, asymmetry of the anterior cerebral artery a1 segment (A1) bilaterally was commonly found in CT angiography (CTA) examination in patients with internal carotid artery stenosis (ICAS). ![]() A combination of TCD and CTA examination of A1 can assist in judging the location and degree of ICAS. When A1 on the side of ICAS was slender or non-visualized, the Vm of A1 was significantly slower than that on the contralateral side ( P < 0.001).Ĭonclusion: The CTA manifestations of A1 on the side of ICAS embodied the overall changes of the intracranial hemodynamics after ICAS. When unilateral ICAS was ≥70%, the presentation of A1 on the stenotic side was more slender or non-visualized compared to that on the contralateral side, while in cases with unilateral stenosis <70% or bilateral stenosis with a similar degree of stenosis, A1 were mainly symmetrical. Results: In the case of unilateral ICAS, the difference in Vm of A1 between the stenotic and the contralateral side was the most significant relative to the stenosis degree. The degree of ICAS according to the different manifestations of A1 and the hemodynamics of A1’s adjacent vessels were also analyzed. The differences in CTA presentations of A1 and hemodynamics between the vessels on the stenotic and contralateral sides were analyzed according to the different degrees of stenosis. Hemodynamic indexes were detected by transcranial Doppler (TCD). The degree of ICAS and symmetry of A1 were evaluated by CTA examination. Methods: A total of 97 cases were selected. ![]() Objective: This study aimed to evaluate whether CT angiography (CTA) manifestations in anterior cerebral artery a1 segment (A1) were related to the hemodynamics in patients with internal carotid artery stenosis (ICAS).
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