Prospective ECG-triggered, axial 4-D imaging of the aortic root, valvular, and left ventricular structures: A lower radiation dose option for preprocedural TAVR imaging

BackgroundTranscatheter valve interventions rely on imaging for patient selection, preprocedural planning, and intraprocedural guidance.ObjectiveWe explored the use of prospective electrocardiogram (ECG)–triggered 4-dimensional (4-D) CT imaging in patients evaluated for transcatheter aortic valve replacement (TAVR).MethodsA total of 47 consecutive patients underwent 128-slice dual-source CT with wide-window dose-modulated prospective ECG-triggered, axial acquisition of the aortic root, reconstructed during diastolic and systolic cardiac phases. Image quality was evaluated, aortic root and left ventricular (LV) geometry and function were analyzed, and radiation exposure was estimated.ResultsImage quality was generally good, with 41 of 47 (87%) patients scored as good or excellent. The mean aortic valve area was 0.93 ± 0.24 cm2. Mean LV ejection fraction was 56.8% ± 16.4%, and mean LV mass was 130.4 ± 43.8 g. The minor diameter of the annulus was larger in systole (systole, 2.29 ± 0.24 cm; diastole, 2.14 ± 0.25 cm; P = 0.006), but the mean and major diameters did not vary significantly between systole and diastole. The mean estimated effective dose was 5.9 ± 2.4 mSv.ConclusionMultiphase, prospective ECG-triggered axial image acquisition is a lower dose acquisition technique for 4-D aortic root imaging in patients being considered for TAVR.