Effects of Dose Reduction on Diagnostic Image Quality of Coronary Computed Tomography Angiography in Children Using a Third-Generation Dual-Source Computed Tomography Scanner

Abstract

Performing coronary computed tomography angiography (CCTA) using third-generation dual source computed tomography (3G-DSCT) scanners results in radiation dose reduction without sacrificing image quality in adults. The largest dose reductions have been reported with prospectively gated, high-pitch imaging. However, there are limited data to determine if these benefits extend to pediatric patients. We evaluated image quality and radiation dose range of CCTA performed in children using a 3G-DSCT scanner. A retrospective review of 44 children (median age 10years, range 0.6 to 17) who underwent imaging to evaluate coronary artery origins (n = 27), Kawasaki disease (n = 12) or other coronary abnormalities (n = 5) were performed. General anesthesia was used in 9/44 (20%) patients and a β blocker was administered in 19/44 (43%). Prospectively gated high-pitch scanning was most frequently used (n = 24). Other techniques used included prospectively-gated "step and shoot" (n = 14), retrospectively gated (n = 2) and nongated high-pitch scan (n = 4). Median effective radiation doses were lowest for prospectively gated high-pitch scans (0.5mSv, range 0.4 to 0.7). Overall coronary artery image quality grade (1-excellent and 4-nondiagnostic) was acceptable for all electrocardiography-gated techniques, with no significant differences between high-pitch and "step-and-shoot" scan types (median 1, range 1 to 3 vs median 1, range 1 to 4, p = 0.22). Image quality grade was diagnostic (1 to 3) for all proximal coronary segments but rare distal segments were nondiagnostic (0.8% segments for gated high-pitch scan). In conclusion, CCTA can be performed in children using 3G-DSCT scanners withacceptable image quality. Prospectively gated high-pitch scans deliver the lowest radiation dose without reduction in image quality compared with conventional scan techniques.