Radiation dose and image quality of 70 kVp cerebral CT angiography with optimized sinogram-affirmed iterative reconstruction: comparison with 120 kVp cerebral CT angiography.

Abstract

To evaluate radiation dose, image quality, and optimal level of sinogram-affirmed iterative reconstruction (SAFIRE) of cerebral CT angiography (CTA) at 70 kVp. One hundred patients were prospectively classified into two groups: Group A (n = 50), 70 kVp cerebral CTA with 5 levels of SAFIRE reconstruction (S1-S5); and Group B (n = 50), 120 kVp with filtered back projection (FBP) reconstruction. CT attenuation values, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured. Subjective image quality was evaluated. Effective dose (ED) was estimated. CT attenuation and noise of the ICA and MCA in Group A were higher than those of Group B (all P < 0.001) while the SNRICA, SNRMCA, CNRICA, and CNRMCA of Group A at S4-5 were comparable to (P > 0.05) or higher than in Group B (P < 0.05). There was no difference in overall image quality between Group A S3-5 and Group B (P > 0.05). ED was 0.2 ± 0.0 mSv for Group A with 85 % ED reduction in comparison to Group B (1.3 ± 0.2 mSv). Cerebral CTA at 70 kVp is feasible, allowing for substantial radiation dose reduction. SAFIRE S4 level is recommended for obtaining optimal image quality. • 70 kVp cerebral CTA is feasible and provides diagnostic image quality. • 70 kVp cerebral CTA resulted in 85% effective dose reduction. • S4 level of SAFIRE is recommended for 70 kVp cerebral CTA.