First-pass MRI compartmental analysis at the chronic stage of infarction: myocardial flow reserve parametric map

The regional myocardial flow and flow reserve (MFR) have been assessed using compartmental analysis of Gd-enhanced MRI first-pass data in 7 patients with atypical chest pain, and in 15 patients with previous transmural myocardial infarction. The FE product (Flow × Extraction coefficient), derived from the modified KeTy equation, has been measured in the regions corresponding to the Tetrofosmine-SPECT fixed defect and in the remote normal regions. The FE product at rest and hyperhemic FE product were similar in healed revascularised tissues (70.5±15.6 and 112.5±19.5 ml/mn/100 g respectively) and in the normal myocardium (76.2±18.3 and 142.2±33.0 respectively). In contrast the FE index (48.8±15.2 and 60.7±18.0 respectively, p<0.01 versus the two previous groups) and the MFR (1.27±0.20 vs. 1.91±0.29 in normal regions) were reduced in healed fibrotic tissues when the infarct-related artery remained occluded. Myocardial flow reserve maps allowed the authors to identify correctly the regions corresponding to an occluded infarct-related artery