Estimation of the area at risk in myocardial infarction of rats by means of I-123 beta-methyliodophenyl pentadecanoic acid imaging

Clinical investigations have suggested that the defects in SPECT images of a free fatty acid analog, I-123 beta -methyliodophenyl pentadecanoic acid ( BMIPP) may indicate the ischemic risk area. To elucidate whether I-123 BMIP P can indicate the: area at risk of ischemia, ex-vivo autoradiography was p erformed in rats whose left coronary artery was occluded for 60 min and the n reperfused. I-123 BMIPP was injected at the acute stage (n = 10), or the subacute stage (7 days after reperfusion; n = 9). Infarction and the area a t risk were identified by triphenyl tetrazolium chloride staining and injec tion of methylene blue during religation just before sacrifice, respectivel y. The BMIPP uptake in the risk area was significantly lower than that in t he remote area at the acute (risk, 53.7 +/- 23.3% of the uptake at right ve ntricle, mean +/- SD; remote, 109.3 +/- 11.8%; p < 0.01) and subacute (risk , 52.5 +/- 11.5%; remote, 97.9 +/- 14.3%; p < 0.01) stages. In addition, th e area with reduced uptake of I-123 BMIPP showed a significant correlation with the area at risk both at the acute (r = 0.98, p < 0.01) and subacute ( r = 0.92, p < 0.01) stages. In conclusion, the area at risk can be evaluate d by I-123 BMIPP both at the acute and subacute stages.