Approach to Assessing Myocardial Perfusion in Rats Using Static [13N]-Ammonia Images and a Small-Animal PET

Semi-quantitative, static positron emission tomography (PET) has been used to perform an initial approach to the assessment of [13N]-ammonia perfusion studies aimed to elucidating the effect of injecting human embryonic stem cell-derived (hES) hemangioblasts on infarcted rat hearts. Female NIH nude rats underwent occlusion of the left anterior descending coronary artery for 30 min before reperfusion. Either one million hES-derived hemangioblasts (n = 5) or control media (n = 4) were injected into the site of the infarct 1 day post-myocardial infarction (MI) under high-resolution echocardiography guidance. PET imaging was performed 6 weeks after MI induction, and uptake polar maps were created by sampling the left ventricle at equidistant slices from the base to the apex and measuring the average myocardium value at three contiguous voxels to minimize partial volume effects. Statistical comparison between treatment and control groups was done with a Mann-Whitney U test. Myocardium uptake ratios for treated and untreated subjects show statistically significant difference (98% certainty). The straightforward procedure described here (similar to those commonly used in clinical routine) was sufficient to yield statistically significant perfusion differences between the treated and untreated animals despite the small sample size.