Myocardial perfusion imaging with 99mTc-tetrofosmin in patients with hypertrophic cardiomyopathy

Myocardial perfusion abnormality and distribution change of 99mTc-tetrofosmin (TF) were examined at exercise in hypertrophic cardiomyopathy (HCM). Subjects were 22 HCM patients (19 males and 3 females, average age 55 y) with mean wall thickness of 23 mm as determined by echocardiotomography. 99mTc-TF (370 MBq) was intravenously administered during the maximum exercise loading with the bicycle ergometer. At 30 and 180 min later, SPECT was performed with a digital gamma camera GCA901A (Toshiba) or prism 2000XP (Picker), which were equipped with a high resolution collimator for low energy. Left ventricle image was divided into 17 regions, of which 99mTc-TF accumulation was graded from score 0 (normal) to 3 (defect). Afterward, SPECT at rest was also done with 740 MBq of 99mTc-TF. HCM myocardial perfusion abnormality at exercise could be evaluated by comparison of SPECTs at exercise and at rest. At 180 min after exercise, reverse re-distribution was frequently observed. (K.H.)