Imaging Apoptosis with 99mTc-Annexin-V in Experimental Subacute Myocarditis

99mTc-Annexin-V (ANX), which allows in vivo detection of apop-totic cells, is potentially a promising noninvasive tool to diag-nose myocarditis. To test this assumption, we compared the myocardial uptake of ANX (imaging and quantitative autora-diography) in experimental subacute myocarditis (Wistar Bonn/ Kobori rats [WBN/Kob]) and in normal Wistar rats. WBN/Kob is an inbred strain of Wistar rat in which myocardial injury mim-icking subacute catecholamine-induced myocarditis spontane-ously develops (course duration, 18 mo). The apoptotic myo-cardial rates were determined by immunohistochemical studies. Methods: Fourteen WBN/Kob rats (8–10 mo old) and 12 control rats were injected with ANX (7.4 MBq/100 g). Ten-minute ante-rior planar thoracic images (matrix, 128 128) were obtained using a pinhole collimator, 1 and 4 h after injection. Heart-to-lung activity ratios were calculated on the scintigrams. Fou