Myocardial kinetics of Tc-MIBI in canine myocardium after dipyridamole

Technetium 99m-hexakis-2-methoxy-2-methylpropyl-isonitrile (Tc-MIBI) is a promising new myocardial perfusion imaging agent producing excellent rest images. Imaging, however, will need to be performed with exercise or dipyridamole to detect ischemia and to differentiate salvaged but still ischemic my...

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Bibliographic Details
Published in:Circulation (New York, N.Y.) N.Y.), 1990-02, Vol.81 (2), p.628-636
Main Authors: GLOVER, D. K, OKADA, R. D
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cardiology. Vascular system
Contrast Media
Coronary Disease - diagnostic imaging
Dipyridamole
Dogs
Heart - diagnostic imaging
Medical sciences
Myocardium - metabolism
Nitriles
Organotechnetium Compounds
Radionuclide Imaging
Technetium Tc 99m Sestamibi
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Summary:Technetium 99m-hexakis-2-methoxy-2-methylpropyl-isonitrile (Tc-MIBI) is a promising new myocardial perfusion imaging agent producing excellent rest images. Imaging, however, will need to be performed with exercise or dipyridamole to detect ischemia and to differentiate salvaged but still ischemic myocardium from scar. Accordingly, 12 dogs were given mild-to-moderate left circumflex coronary stenoses (group 2), and 10 dogs were given severe stenoses (group 3). In five control dogs (group 1), there was no stenosis. After an intravenous infusion of dipyridamole (0.08 mg/kg/min for 4 minutes), Tc-MIBI was injected into the right atrium. Over the next 4-hour study period, myocardial Tc-MIBI activities were continuously monitored in both the left anterior descending (LAD) (normal) and left circumflex (LCx) (ischemic) coronary artery (ischemic) zones using miniature cadmium telluride radiation detectors and serial gamma camera images were acquired when necessary. Tc-MIBI was rapidly taken up by nonischemic, mild-to-moderate, and severe ischemic myocardium. The initial myocardial uptake of Tc-MIBI was linearly related (r = 0.97) to regional myocardial blood flow at rates up to 2.0 ml/min/g. After the initial uptake, the mean 4-hour fractional myocardial clearance was similar between the control (0.09 +/- 0.03 [+/- SEM]) and group 2 (0.07 +/- 0.03) and group 3 (0.09 +/- 0.03) ischemic zones. Tc-MIBI blood clearance was rapid and biexponential with an initial fast clearance phase followed by a slow clearance phase.
ISSN:0009-7322
1524-4539
DOI:10.1161/01.cir.81.2.628