# Manganese‐enhanced MRI during remotely induced myocardial ischemia reperfusion injury in male mice

## TL;DR

Manganese-enhanced MRI detects early heart damage in mice more accurately than traditional methods during a new remote ischemia test.

## Contribution

A novel in-scanner remote occlusion technique enables real-time MEMRI assessment of acute myocardial ischemia in mice.

## Key findings

- MEMRI detected acute hypo-perfusion in ischemic territories with high specificity.
- LGE MRI overestimated infarct size compared to histology.
- MEMRI perfusion deficits correlated with functional decline and confirmed infarcts.

## Abstract

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.