Cerebral Artery Calcification Assessment Protocol

All patients underwent multidetector brain CTA using a 64-slice spiral CT device (GE Healthcare, Milwaukee, WI, USA). The parameters were as follows:120 kVp, 140 mA, 0.9-mm section thickness, 0.9-mm slice acquisition interval, and intravenous administration of 80 mL of iohexol at a rate of 5.0 mL/s^{15 (link)}. Bone window CT images covered the whole brain (from the skull base to the vertex), to identify the presence of IAC. IAC lesions were defined as high density lesions with a median density greater than 130 Hounsfield units^{16 (link)}. We used the 5-point scale semi-quantitative scoring system proposed by Babiarz et al. to evaluate IAC^{17 (link)}. We selected the highest calcification score for each cerebral artery and added the calcification score of all evaluated artery to get the patient’s total calcification score. We distinguished the severity of IAC according to the total calcification score. 0 score for absent, 1–4 for mild, 5–8 for moderate, and 9–12 for severe degree^{18 (link)}. Two experienced neurologists independently reviewed the images from CT angiography and graded the degree of IAC.