[The Difference of CT Value Related to Monitor Position in the Head CT-angiography Bolus Tracking Method for Patients with Subarachnoid Hemorrhage].

The head computed tomography-angiography (head CT-A) examination is excellent for the detection and diagnosis of cerebral artery aneurysm. If we use bolus tracking method when implementing this examination, we must choose a monitoring point. We investigated the influence which the monitoring point (MCA or carotid-A) exerts on the CT value. As for the result, MCA monitoring point method was more excellent than the carotid artery monitoring point method. The CT value was higher about 50 HU in the MCA monitoring point than in the carotid artery monitoring point (average;carotid artery: 349.6±57.8 HU, MCA: 413.2±67.9 HU). So, we conclude that in the bolus tracking method of monitoring point of head CTA, MCA monitoring point should be used.