• Xiang-Jun Yang, Yong-Ming He, Yi-Wei Wu, Bin Zhang, Jie Hui, Ting-Bo Jiang, Jian-Ping Song, Zhi-Hua Liu, and Wen-Ping Jiang.
• Department of Cardiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China. yang_xiangjun@163.com
• Nucl Med Commun. 2008 Mar 1; 29 (3): 230-8.

ObjectiveTo evaluate the myocardial ischaemia/viability in patients with acute myocardial infarction (AMI) using the ischaemia-avid agent (99m)Tc-HL91.MethodsThirty-three AMI patients received 740 MBq (20 mCi) (99m)Tc-HL91, i.v., first and then 148-185 MBq (4-5 mCi) (201)Tl around 3 h later. The patient underwent initial imaging and 24 h late imaging, 10-15 min and 24 h later, respectively, after intravenous injection of (201)Tl. Myocardial segmental radioactive counts of (99m)Tc-HL91 were quantified by the region of interest technique. The segmental radioactive counts/pixel divided by those of the corresponding left ventricular cavities were ratios, which were compared among normal, ischemic/viable and fixed defect myocardium. The correlation analysis between the segmental scores from (201)Tl imaging and the ratios was performed.ResultsThe cross-talk of (99m)Tc into (201)Tl could be neglected in the present study. Out of the 33 AMI patients, the (99m)Tc-HL91 image quality analysis classified seven cases into excellent, accounting for 21%, eight cases into good, for 24%, eight cases into fair, for 24%, and 10 cases into poor, for 31%. The ratios were 1.16 (1.01, 1.35) ((median (25th to 75th percentile)), 1.15, 0.20 and 1.01 (0.86, 1.30), respectively, in normal, ischaemic/viable and fixed defect myocardium. Significant differences (chi2=17.2069, P=0.0002) were found in the ratios. The ratios of the ischaemic/viable myocardial segments were significantly higher than those of the fixed defect segments. Unexpectedly, the normal myocardial segments took up (99m)Tc-HL91, too, even slightly higher than the ischaemic/viable myocardial segments.ConclusionsMyocardial uptake of (99m)Tc-HL91 is perfusion-dependent as well as ischaemia dependent. (99m)Tc-HL91 hypoxia imaging alone is not sufficient to identify ischaemic/viable myocardium. Dual-isotope imaging with (201)Tl and (99m)Tc-HL91 can characterize the myocardium into normal, ischaemic/viable and necrotic (scarred) myocardium.

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