Dual-source cardiac computed tomography angiography (CCTA) in the follow-up of cardiac transplant: comparison of image quality and radiation dose using three different imaging protocols.

OBJECTIVES: To prospectively evaluate image quality (IQ) and radiation dose of dual-source cardiac computed tomography (CCTA) using different imaging protocols.
METHODS: CCTA was performed in 150 patients using the retrospective ECG-gated spiral technique (rECG) the prospective ECG-gated technique (pECG), or the prospective ECG-gated technique with systolic imaging and automated tube voltage selection (pECGsys). IQ was rated using a 16-segment coronary artery model. Techniques were compared for overall IQ, IQ of the large and the small coronary artery segments. Effective dose was used for comparison of radiation dose.
RESULTS: Overall IQ and IQ of the large segments showed no differences between the groups. IQ analysis of the small segments showed lowered IQ in pECGsys compared to rECG (p = 0.02), but not to pECG (p = 0.6). Effective dose did not differ significantly between rECG and pECG (p = 0.13), but was significantly lower for pECGsys (p < 0.001 vs. rECG and pECG).
CONCLUSION: Radiation dose of dual-source CCTA in heart transplant recipients is significantly reduced by using prospective systolic scanning and automated tube voltage selection, while overall IQ and IQ of the large coronary segments are maintained. IQ appears to be lower compared to retrospective techniques with regard to small coronary segments. KEY POINTS: • Cardiac computed tomography angiography is useful for cardiac allograft vasculopathy assessment. • Despite elevated heart rate, dose reduction in cardiac computed tomography is possible. • Prospective systolic gating and automated tube voltage selection enable 50 % dose reduction.