In vivo quantitation of regional myocardial blood flow by positron-emission computed tomography.

The potential of positron-emission computed tomography (PCT) for external quantitation of myocardial indicator concentrations and regonal myocardial blood flow (RMBF) and the effect of left ventricular wall thickness on tracer concentration recovery by PCT was examined in seven open-chest dogs. RMBF was determined by the arterial reference technique in vivo and in vitro. Together with gamma-emitting Ce-141 microspheres, positron-emitting Ga-68-labeled microspheres were injected into the left atrium and their myocardial concentrations determined in vivo from gated and ungated cross-sectional PCT images. It is concluded that (1) myocardial indicator tissue concentrations, and thus, RMBF, can be accurately measured by PCT provided corrections are made for the effect of wall thickness on count recovery; (2) these corrections can be made using in vivo echocardiography; and (3) gated PCT imaging can be used to evaluate regional myocardial systolic wall thickening as an index of regional function and combined with measurements of RMBF or regional metabolism. The results represent a framework for the noninvasive measurement of RMBF and metabolism by PCT in the experimental animal and in man.