Manganese-enhanced MRI during remotely induced myocardial ischemia reperfusion injury in male mice.

Early assessment of myocardial viability post-ischemia is crucial to mitigate adverse remodeling and optimize therapy. Current noninvasive methods like late gadolinium enhancement (LGE) MRI may overestimate infarct size. Manganese-enhanced MRI (MEMRI) emerged as a promising alternative, offering greater specificity in assessing myocardial damage. We evaluated MEMRI alongside LGE and histology in a murine ischemia-reperfusion model using a novel "in-scanner" remote occlusion technique for real-time imaging during acute ischemia. Male C57BL/6 mice (n = 16) underwent left anterior descending artery occlusion (n = 7), sham surgery (n = 6), or no intervention (n = 3). MEMRI (0.1 mmol/kg MnCl2) during ischemia (0-60 min) and LGE (0.1 mmol/kg Gd-DOTA, 24 h post-surgery) quantified perfusion deficits and infarct size. MEMRI detected acute hypo-perfusion (lateral wall signal reduction: p < 0.01 vs. septal), confined to the occluded territory, while LGE overestimated infarct size (p = 0.0225 vs. histology). Ischemic mice showed adverse remodeling with reduced ejection fraction (61.37% vs. 71.92%, p < 0.01). MEMRI-derived perfusion deficits correlated with functional decline and histology-confirmed infarcts. Pre-occlusion T1 times did not differ between ischemic and sham groups (p = 0.85), confirming technique specificity. MEMRI enables early, accurate ischemic injury detection and predicts cardiac dysfunction, outperforming LGE in infarct size determination. Our remote occlusion technique facilitates real-time perfusion assessments, enhancing preclinical myocardial ischemia studies.