Image quality and radiation dose of a prospectively electrocardiography-triggered high-pitch data acquisition strategy for coronary CT angiography: The multicenter, randomized PROTECTION IV study.

BACKGROUND: Concerns have been raised about radiation dose of coronary CT angiography. Although high-pitch acquisition technique yields high potential for radiation dose savings, it is more vulnerable to artifacts, which impair diagnostic image quality.

OBJECTIVE: The purpose of this study was to compare 2 scan strategies for coronary CT angiography: a high-pitch helical scan first or a conventional scan first strategy.

METHODS: In this prospective, multicenter trial, we randomized 303 consecutive patients with a low and stable heart rate to either of the aforementioned mentioned strategies. Intravenous β-blockers were administered to achieve target heart rates. All scans were performed on a second-generation dual-source CT scanner. In case of nondiagnostic image quality, coronary CT angiography was allowed to be repeated. The primary end point was to demonstrate noninferior image quality in the high-pitch group. Image quality was assessed on a 4-point scale (1: nondiagnostic, 4: excellent). Secondary end point was total radiation dose.

RESULTS: In the high-pitch helical first group, repeat scanning was necessary in 21 patients compared with 14 patients in the conventional first scan group (P = .25). Image quality in the high-pitch group was noninferior compared to the conventional scan group (3.81 ± 0.35 vs. 3.83 ± 0.37; P for noninferiority <.0001). The total effective radiation dose estimate was 58% lower in the high-pitch group (2.0 ± 2.4 vs. 4.7 ± 4.8 mSv; P < .0001).

CONCLUSIONS: In patients with a low and stable heart rate diagnostic image quality can be maintained with a high-pitch helical scan first strategy while 58% of radiation dose can be saved.