Background: Coronary computed tomography angiography (CCTA) is an established modality for ruling out coronary artery disease. However, it has been suggested that CCTA may be a source of non-negligible radiation exposure.
Objectives: To evaluate the potential degradation in coronary image quality when using prospective gated (PG) CCTA as compared with retrospective gated (RG) CCTA in chest pain evaluation.
Methods: The study cohort comprised 216 patients: 108 consecutive patients in the PG CCTA arm and 108 patients matched for age, gender and heart rate in the RG CCTA arm. Scans were performed using a 64-slice multidetector CT scanner. All 15 coronary segments were evaluated subjectively for image quality using a 5-point visual scale. Dose-length product was recorded for each patient and the effective radiation dose was calculated
Results: The PG CCTA technique demonstrated a significantly higher incidence of step artifacts in the middle and distal right coronary artery, the distal left anterior descending artery, the second diagonal, the distal left circumflex artery, and the second marginal branches. Nevertheless, the diagnostic performance of these scans was not adversely affected. The mean effective radiation doses were 3.8 ± 0.9 mSv vs.17.2 ± 3 mSv for PG CCTA and RG CCTA, respectively (P < 0.0001).
Conclusions: Artifacts caused by the PG CCTA technique (64 MDCT) scanners tended to appear in specific coronary segments but did not impair the overall diagnostic quality of CCTA and there was a marked reduction in radiation exposure. We conclude that 64-slice PG CCTA is suitable for clinical use, especially for acute chest pain "fast track" evaluation targeted at relatively young subjects in a chest pain unit.