Quantitative contrast media dose evaluation for cranial computed tomography

The goal of this study was to quantitatively evaluate the CT enhancement characteristics of selected intracranial blood vessels using four different volumes of a contrast medium under otherwise identical conditions in order to help determine a cost-effective dose. In a double blind, prospective manner, 100 patients referred for contrast-enhanced cranial CT were randomly assigned to receive one of four different volumes (50, 75, 100 or 120 ml) of ioversol 320 mg I/ml which was subsequently administered intravenously at a rate of 1 ml/s via a power injector. Unenhanced images were also obtained. Scanning times, slice thickness and other parameters were identical in all patients. Scanning was initiated immediately following delivery of the full volume of contrast. Region of interest Hounsfield unit measurements were acquired in a standardized manner using a 1 mm diameter circle on the pre- and post-contrast scans of the supraclinoid left internal carotid artery (LICA), supraclinoid right internal carotid artery (RICA), basilar artery (BA), and torcular region (TR). The mean enhancement value (in Hounsfield units) for the 50 ml, 75 ml, 100 ml and 120 ml dose groups respectively were as follows for each vessel: LICA 29.9, 41.5, 63.9, 64.6; RICA 30.1, 39.4, 62.6, 65.1; BA 30.0, 41.7, 66.0, 71.9; TR 31.7, 46.8, 68.9, 74.3. There was no statistically significant (p > 0.05) difference in enhancement in any of the four vessels when the 120 ml volume was delivered compared to the 100 ml volume. However, there was a statistically significant (p < 0.05) improvement in enhancement in all four vessels when 100 ml of contrast was administered compared to 75 ml.(ABSTRACT TRUNCATED AT 250 WORDS)