99m Tc-HL91: “Hot Spot” Detection of Ischemic Myocardium In Vivo by Gamma Camera Imaging

• Published in: Circulation (New York, N.Y.) N.Y.), 1998-06, Vol.97 (25), p.2557-2566
• Main Authors: Okada, Robert D., Johnson, Gerald, Nguyen, Kiem N., Liu, Zhonglin, Edwards, Barbara, Archer, Colin M., North, Timothy L., King, Adam C., Kelly, James D.
• Format: Article
• Language: English
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.97.25.2557

Background — 99m Tc-HL91 is a new hypoxia imaging agent that demonstrates increased uptake and retention in globally hypoxic myocardium in vitro. The purpose of this study was to determine whether 99m Tc-HL91 could detect regional ischemia in vivo by gamma camera imaging. Methods and Results —Eight open-chest dogs with left circumflex (LCx) stenoses were studied. Injection of 5 mCi of 99m Tc-HL91 and microspheres was followed by imaging over 4 hours. Heart slices were imaged, then stained with triphenyltetrazolium chloride (TTC), and tissues were well-counted. TTC staining demonstrated no injury. Mean LCx blood flow was 0.32±0.04 mL · min −1 · g −1 , and mean left anterior descending coronary artery (LAD) flow was 0.96±0.02 mL · min −1 · g −1 (ratio, 0.33). “Hot spots” were detected in 8 of 8 experiments in vivo within 60 minutes and improved over 4 hours. Region of interest analysis of LCx/LAD activity ratios demonstrated significant increases within 30 minutes (final ratio, 3.0; P