Characterization of Infarct Size and Remodeling Using CMR and PET in Mice Models of Reperfused and Non-Reperfused...

Background/Objectives: Unlike post-mortem histopathology, cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) enable longitudinal assessment of structural, functional, and metabolic alterations in preclinical myocardial infarction models. This study aims to describe the temporal evolution of infarct size and systolic function by CMR and glucose consumption via PET, explore their differences in non-reperfused and reperfusion infarction models, and assess their capacity to predict histology-derived infarct size and systolic function at chronic phase CMR. Methods: Two murine models of myocardial infarction were generated using permanent (non-reperfused, n = 8) or transient (reperfused, n = 9) coronary occlusion. CMR and fluorine-18 2-fluoro-2-deoxyglucose PET imaging were performed at baseline and at 1, 7, and 21 days post-infarction to quantify infarct size, systolic function, and myocardial glucose metabolism. Infarct size was also assessed using Masson's trichrome staining. Results: At 24 h post-infarction, CMR-derived infarction together with significant reduction in systolic function and glucose metabolism were already noted in both models. At 21-day CMR, however, reperfused mice showed lower infarct size and more preserved systolic function compared to their non-reperfused counterparts, while no differences in glucose metabolism were reported. Infarct size and systolic function at 1-day CMR and the number of segments with reduced glucose consumption at 1-day PET independently predicted histology-derived infarct size and long-term systolic function. Conclusions: Combined PET/CMR imaging enables non-invasive, sequential evaluation of infarct size, systolic function, and glucose metabolism in experimental myocardial infarction. This multimodality approach is well suited for assessing the efficacy of emerging therapies in preclinical research.