Accuracy of pulmonary vascular dimensions estimated with the dynamic spatial reconstructor.

Measurements of pulmonary artery conduit dimensions were obtained in two children after first-stage right ventricular outflow tract reconstruction for congenital pulmonary atresia. These conduits provide an opportunity for evaluation of measurement accuracy of intrathoracic vascular structures that is not possible with the same objectivity in the native vascular tree. Patients were scanned in the dynamic spatial reconstructor (DSR), a high-speed CT scanner, during injection (0.7-1.2 ml/kg) of contrast agent into the pulmonary artery conduit. As the DSR is a volume imaging system, all angles of view are always available from one angiogram, and it can provide images of oblique planes through the structure of interest. In the patient with the 12-mm diameter conduit (113 mm2 area), the cross-sectional area of DSR measurement was 115 +/- 5 mm2 (mean value +/- SD), the roll film value was 84 +/- 6 mm2, and the cineangiogram value was 97 +/- 3 mm2. In the patient with the 8-mm diameter conduit (50 mm2 area), the cross-sectional area of DSR measurement was 47 +/- 5 mm2, the roll film value was 36 +/- 3 mm2, and the cine film value was 35 +/- 4 mm2. The DSR scan (8 s) involved 0.63-0.95 R/s exposure at the sternum, whereas the biplane cineangiogram (3-5 s) involved 0.8 R/s. Based on these data, we conclude that a single DSR scan provides accurate measurements of pulmonary anatomy and vessel dimensions.