Computed tomographic angiography may be used for assessing the dilatation of the anterior choroidal and posterior communicating arteries in patients with moyamoya syndrome.

OBJECTIVE: To evaluate the feasibility of CT angiography (CTA) for assessing anterior choroidal artery (AChA) and posterior communicating artery (PComA) dilatation in patients with moyamoya syndrome (MMS). METHODS: Eighty-eight MMS patients who underwent digital subtraction angiography (DSA) and CTA within 1 month were enrolled. The AChA was graded using both DSA and CTA. Given the features of dual blood supply, DSA was firstly used for grading of the PComA. Then, the calibers of PComA, P1 or P2 segment of the posterior cerebral artery (PCA), were recorded from CTA. Taking DSA as a reference standard, the optimal cutoff values of the PComA/P1 or PComA/P2 were calculated to determine the dilatation of PComA. Both the AChA and PComA were classified as extreme dilatation (ED, grade 2) or non-extreme dilatation (NED, grade 0 or 1). RESULTS: The AChA was evaluated in 149 affected hemispheres of 88 patients while the PComA was evaluated in 70 affected hemispheres of 49 patients. The sensitivity and specificity of CTA in diagnosing AChA-ED were 92% and 93.5% respectively. Both the PComA/P1 (p < 0.001) and PComA/P2 (p = 0.4) ratios were increased in the PComA-ED group with the former yielding a better detecting performance than the latter (AUC = 0.92 vs 0.85, p = 0.046). When using 0.71 as a cutoff value, the sensitivity and specificity of the PComA/P1 ratio for diagnosis of PComA-ED cases were 91.3% and 83.3% respectively. CONCLUSIONS: CTA could be used for the AChA classification in MMS patients, while a PComA/P1 ratio greater than 0.71 indicates the existence of PComA-ED. KEY POINTS: • CTA showed a high sensitivity, specificity, and accuracy in diagnosing AChA-ED in patients with MMS. • PComA/P1 ratio greater than 0.71 on CTA signified an extremely dilated PComA. • CTA could be used to assess the dilatation of AChA and PComA in MMS patients, especially for routine postoperative follow-up.