Evaluation of ECG gating and hybrid subtraction for intraarterial digital subtraction thoracic aortography

A comparative study was made of ECG-gated and nongated intraarterial digital subtraction angiography of the thoracic aorta by using conventional temporal subtraction and combined temporal/energy (hybrid) subtraction. ECG-gated studies were acquired at three frames per cardiac cycle. In 85% of patients, gated conventional subtraction resulted in studies of superior image quality in comparison with those obtained with hybrid techniques, both gated and nongated. In the 15% in whom hybrid subtraction studies were judged superior, the hybrid images were almost exclusively integrated by video frame averaging and thus were nongated. In a separate subset of patients who had conventional nongated studies, there was no difference in the percentage of diagnostic studies (93%) and nondiagnostic studies (7%) when compared with conventional gated temporal subtraction. Cardiac gating appears to be superior to hybrid subtraction for studies of the thoracic aorta that use intraarterial digital subtraction angiography, but...