FIG 1. CT calcification scores.

A, Circumferential nature of cavernous carotid artery calcification on this CT scan, filmed in a bone window, warrants a grade of 4 (360 degrees of involvement).

B, If the calcification is between 90 and 270 degrees of involvement, it is graded as a 3. The thickness of the calcification, judged by the centimeter scale, was 2 mm in this case.