Increased Lung Uptake During Myocardial Scintigraphy Improves the Detection and Localization of Coronary Artery Disease

Abstract

Increased lung uptake during exercise thallium 201 scanning denotes severe ventricular hypofunction. To assess whether there is any relationship between this finding and the stenosis of a single coronary artery, the authors studied 140 patients (age 57.5 ±12 years) with both exercise thallium and coronary angiography within three months. A planar view was acquired for two hundred forty seconds immediately postexercise and prior to the single photon emission computed tomography acquisition. Two identical regions of interest outlining the left ventricle and the right lung in the planar view were used for calculation of the lung uptake, expressed as a lung-to-heart counts ratio. The patients were divided into four angiographic groups: (I) lesions at the left anterior descending (LAD), n=35; (II) stenosis at the circumflex (CRX), n=35; (III) stenosis at the right coronary artery (RCA), n=35; and (IV) another group of 35 normal subjects serving as controls. No patient had a previous myocardial infraction (MI) or any cardiac operation. Patients in groups I (0.53 ±0.094) and II (0.44 ±0.072) had higher lung uptake than those in groups III (0.43 ±0.061) or IV (0.42 ± 0.050) . There was no differ ence between groups III and IV, or II and IV, but the difference between I and IV was of statistical significance (P < 0.001). Hence, the authors conclude that reversible defects consisting of ischemia at the LAD territory induce more severe left ventricular dysfunction during peak exercise and this is demonstrated as an increase in the thallium lung uptake, whereas the RCA or CRX single lesions have to have other additional factors (MI or hyper tension) in order to produce the same phenomenon.