Optimization for the Contrast Enhancement at Head Computed Tomography Angiography by using the Patient Body Size Indexes: Identifying the Patient Body Size Indexes with the Most Significant Correlation

To identify the body size index (BSI) that exhibited the most significant correlation with intracranial artery enhancement on head computed tomography angiography (CTA) images. Our retrospective study received institutional review board approval, and the requirement for informed patient consent was waived. From April 2020 to October 2021, 99 patients with vascular disease underwent head CTA, during which the CT number (in Hounsfield units [HU]) of the middle cerebral artery at the proximal (M1) region was recorded on both unenhanced and arterial phase scans. We calculated the changes in contrast enhancement per iodine dose (ΔHU/gI) to assess the correlation with BSI. Subsequently, we conducted linear regression analyses between ΔHU/gI and BSI. To evaluate the effects of age, sex, BSI, and scan delay on theΔHU/gI, we used multivariate regression analysis. The ΔHU/gI of the middle cerebral artery during arterial phase was 15.8 ± 4.1 HU/gI. ΔHU/gI and body surface area (BSA) showed the strongest inverse correlation (r = 0.779). Among the BSIs considered in our study, BSA was the most important estimated factor for the ΔHU/gI of the middle cerebral artery on head CTA images acquired during the arterial phase. The BSA and scan delay had significant effects on ΔHU/gI (standardized regression: BSA −0.33, scan delay 0.02; p < 0.05, respectively). Patient BSA and scan delay significantly affected the contrast enhancement of M1 on head CTA images.