Modified Blalock-Taussig shunt patency for pulmonary atresia: assessment with electron beam CT

PURPOSE: The purpose of this work was to evaluate electron beam CT (EBCT) for the noninvasive assessment of modified Blalock-Taussig (BT) shunt patency in patients with pulmonary atresia. METHOD: Five infants and children with pulmonary atresia and modified BT shunts underwent contrast-enhanced EBCT. Modified BT shunts from the subclavian artery to the pulmonary artery were performed to improve the pulmonary blood flow. Electrocardiogram (ECG)-triggered EBCT was obtained with a 100 ms exposure, 3 mm section thickness, and 2 mm table feed after intravenous administration of contrast material. Three-dimensional (3D) or maximum intensity projection (MIP) EBCT images were compared with conventional angiography. The visibility of modified BT shunts was graded and recorded with use of a four-point scale. RESULTS: Satisfactory visualization was achieved in both 3D and MIP EBCT images to evaluate modified BT shunt patency. CONCLUSION: Contrast-enhanced 3D or MIP EBCT imaging with ECG trigger may be used as an effective substitute to evaluate modified BT shunts with low radiation dose exposure.