CT Angiography Covering Both Cervical and Cerebral Arteries on a 16-Detector Row System: Modification of Contrast Dose and Injection Rate by Patient Weight

We assessed the feasibility of modifying the contrast dose and injection rate based on patient weight in four patient groups in whom CT angiography was performed with contrast agent 350 mgI/mL at different injection doses in combination with a saline flush (40 mL). Patients were assigned to one of four groups: group A: injection dose (ID) of 1.3 mgI/kg; group B: ID of 1.1 mgI/kg; group C: ID of 0.9 mgI/kg; and group D (the control group): a fixed dose of 75 mL at 3 mL/s (25 s). In groups A to C, the injection time was fixed at 20 s. We measured the attenuation of target vessels and visually assessed the images obtained. The average dose and rates were 81.3/4.1, 63.8/3.2, and 49.4/2.5 (mL/mL/s) for groups A, B, and C, respectively. The doses of groups B and C were significantly smaller that that of group D. Cerebral vessels showed no significant attenuation difference between group D and groups A and B, but the attenuation of only a few assessed regions was significantly lower in group C than in group D. In the visual assessment, no difference was found among the four groups. Cervical and cerebral CT angiograms can be obtained at a dose of 1.1 mgI/kg, which can effectively reduce the contrast dose.