[An evaluation of the carotid bifurcation and of the intracranial circle by angio-spiral computed tomography].

Introduction: Some clinical trials (NASCET, ECTS) have assessed that carotid endarterectomy is protective against stroke in patients with asymptomatic severe carotid stenosis. In order to decrease costs and risks, new diagnostic tools have been developed, such as Magnetic Resonance Angiography (MRA), duplex Ultrasound (US) and more recently Spiral Computed Tomography Angiography (CTA). CTA provides excellent 3D angiography images of the extracranial vessels using a volume rendering technique. This study was aimed at prospectively evaluating the accuracy of CTA in the diagnosis of carotid bifurcation. The circle of Willis was also studied during the same bolus injection. DSA was used as the gold standard technique. Surgery was also used for comparison.

Material And Methods: Spiral CTA and DSA were performed in 106 carotid bifurcations. DSA was performed in all patients within 48-72 hours of CTA. The degree of internal carotid stenosis was evaluated according to NASCET criteria. Degree of stenosis, presence of calcifications, ulcerations and tandem lesions were reviewed by two different neuroradiologists blinded to each other and to the results of the other technique. In 19 cases the size of residual lumen of the ICA was surgically evaluated and correlated with CTA.

Results: There was an overall correlation between CTA and DSA in 94% of cases. Our data are in agreement with the results of the current literature. CT angiograms overrated by one category 6 cases (25%) of mild and one of moderate stenosis (7.14%). Calcifications were seen on spiral CT angiography in 69 (65.09%) carotid bifurcations while DSA detected the presence in 31 (29.24%). Ulcerations were missed by CTA in 3 cases. Five (4.71%) tandem lesions were visualized by DSA distal to bifurcation: 2 (1.88%) were also diagnosed by CTA. The patency of the circle of Willis was assessed in all cases. In 19 cases, the size of ICA stenosis evaluated at surgery was comparable with CTA findings.

Conclusions: In conclusion CTA offers an outstanding alternative to catheter angiography in the evaluation of stenosis-occlusion of the carotid bifurcation. The intracranial circulation can be easily assessed by CTA as well, which allows the study of tandem lesions and of the circle of Willis.