Improved vascular opacification in cerebral computed tomography angiography with 80 kVp

Purpose: We sought to intraindividually compare computed tomography angiographies (CTAs) acquired at 80 kVp and 120 kVp with respect to vessel contrast, noise level, and radiation dose. Material and Methods: CTA was performed on a single-slice CT scanner using tube voltages of 80 kVp and 120 kVp in 29 patients with arteriovenous malformations. Mean Hounsfield Units (HU) were evaluated for different vessels and brain parenchyma. To determine contrast-to-noise ratios (CNRs), noise levels were estimated from phantom measurements. Results: The calculated effective dose to male/female patients was 0.4/0.5 mSv for 80 kVp and 0.7/0.8 mSv for 120 kVp. CT density in blood vessels was between 297 and 458 HU for 80 kVp and 152 and 229 HU for 120 kVp (P < 0.0001). Despite an increased noise level in the low-voltage images, the CNR was 26-59% higher at 80 kVp than at 120 kVp (P < 0.05). Conclusion: The use of a reduced tube potential leads to improved CNR in CTA of the cerebral vasculature and a markedly reduced radiation exposure to patients.