Comparison of flurpiridaz F 18 and FDG for assessment of left ventricular tissue mass following myocardial infarction in rats

Objectives 18F fluorodeoxyglucose (FDG) cardiac imaging has been used to assess myocardial viability. Flurpiridaz F 18 is a newly developed PET myocardial perfusion imaging agent and its heart uptake shows a high agreement with flow at both cardiac stress and rest conditions. This study compared the non-defect tissue mass of the left ventricle measured by flurpiridaz F 18 imaging with the viable tissue mass detected by FDG imaging in normal and myocardial infarcted (MI) rats.

Methods MI was induced in rats by 30 minutes of left coronary occlusion followed by reperfusion. Flurpiridaz F 18 (1 mCi) and FDG (1 mCi) cardiac imaging (2 days apart) was performed in rats before, two days (early MI) and four weeks (late MI) post surgery. A regimen of glucose and insulin was injected before FDG imaging to ensure optimal cardiac uptake. The non-defect or viable left ventricular mass was quantified as the myocardium having ≥50% of maximum activity from images acquired at 20-30 minutes post injection.

Results In control rats before surgery, cardiac imaging with both flurpiridaz F 18 and FDG showed a well-defined left ventricular wall and the left ventricular tissue mass was measured as 1.17±0.04 and 1.11±0.07 cm3, respectively. In early and late stage MI rats, the myocardial defect area was clearly identified by imaging with both agents. The non-defect left ventricular tissue mass measured with flurpiridaz F 18 was slightly larger than the viable tissue mass measured with FDG at early (0.94±0.01 vs. 0.75±0.04 cm3) and late stage MI (1.18±0.04 vs. 0.99±0.09 cm3). In addition, flurpiridaz F 18 imaging showed similar non-defect left ventricular areas at 20 and 80 minutes post injection (suggesting no redistribution and refill-in) in both early and late stage MI.

Conclusions Based on the left ventricular mass measured by the two imaging agents in MI, flurpiridaz F 18 may have the potential to be used to assess myocardial viability