Quantitative lung perfusion scintigraphy in postoperative evaluation of congenital right ventricular outflow tract obstructive lesions.

Improved methods to relieve pulmonary artery stenosis have emphasized the need for an accurate noninvasive method to quantify the pulmonary blood flow. The aim of this study was to compare the roles of Tc-99m MAA perfusion lung imaging, chest x-ray, MRI, and cine-angiography for postoperative evaluation of pulmonary blood flow in patients with congenital right ventricular outflow tract (RVOT) obstructive lesions. Eleven patients underwent chest x-ray, MRI, perfusion lung imaging, and cine-angiography after corrective surgery of RVOT obstruction. The perfusion ratio on lung scans was calculated on the posterior views. The correlation coefficient of the left to right perfusion ratio measured by lung scans obtained with that by visual assessment of chest x-rays, with the most stenotic diameter ratio on MRI and on angiography being 0.57, 0.88 (P < 0.001), and 0.87 (P < 0.001), respectively. Follow-up perfusion lung scans in seven patients, before and after pulmonary artery intervention showed significantly improved perfusion ratios (0.30 +/- 0.11 to 0.70 +/- 0.22; P < 0.001), which were concordant with the clinical findings. The authors conclude that the quantitative perfusion lung scan is the noninvasive method of choice for postoperative evaluation of the pulmonary artery in congenital RVOT obstruction.