QUANTITATIVE PERFUSION IMAGING ASSESSING ACQUIRED DISCRETE PERIPHERALPULMONARY-ARTERY STENOSIS

We present the case an 8-yr-old boy evaluated for anastomotic stenosis of the right pulmonary artery after surgical repair of hemitruncus at 6 wk of age. Pulmonary angiography revealed only mild narrowing and a 10-mm pressure gradient across the anastomosis, but quantitative perf usion imaging demonstrated that the right lung only received 16% of pu lmonary blood flow. Subsequently, balloon angioplasty of the anastomot ic site was performed, resulting in complete resolution of the stenosi s and gradient. Early postangioplasty perfusion imaging demonstrated i ncreased perfusion of the right lung to 35% of total pulmonary blood f low. It is theorized that initially a chronically hyperperfused lung m ay develop more capacious vessels and recruit new capillaries during t he years of hyperperfusion such that a ''perfect'' angioplasty may res ult in less than symmetric perfusion. The inexpensive, noninvasive qua ntitative perfusion study is more sensitive and accurate in evaluating acquired (postsurgical) pulmonary artery stenoses.