New method for measuring myocardial blood flow by high resolution scintigraphy in the excised dog heart

The standard method for measuring myocardial blood flow (MBF) with radioactive microspheres requires processing of selected tissue samples usually from the excised heart, and consequent loss of exact relation to myocardial morphology. A computer-based image processing method was developed by using [99mTc]microspheres (mean particle size 20 microns) for quantitative analysis of MBF in 25 dogs. A computer-controlled gamma camera was used to obtain the images of radioactive microsphere distribution in transaxial slices of the ex vivo heart. Any portion of these slice images could be quantitated by using a computer program based on modification of the formula for determining MBF by the standard microsphere method. Regional myocardial perfusion calculated by this technique correlated well with values obtained with reference microspheres (r = 0.96) over a broad range of MBF. The results show that our new method, accurately and with high resolution, delineated zones of differing MBF and confirmed the increase of MBF in surviving myocardium with healing.