09 Jun 21. Featured Paper
Assessment of stunned & viable myocardium using manganese-enhanced MRI.
Objective: In a proof-of-concept study, to quantify myocardial viability in patients with acute myocardial infarction using manganese-enhanced MRI (MEMRI), a measure of intracellular calcium handling.
Methods: Healthy volunteers (n=20) & patients with ST-elevation myocardial infarction (n=20) underwent late gadolinium enhancement (LGE) using gadobutrol & MEMRI using manganese dipyridoxyl diphosphate.
Patients were scanned ≤7 days after reperfusion & rescanned after 3 months.
Differential manganese uptake was described using a two-compartment model.
Results: After manganese administration, healthy control & remote non-infarcted myocardium showed a sustained 25% reduction in T1 values (mean reductions, 288±34 & 281±12 ms).
Infarcted myocardium demonstrated less T1 shortening than healthy control or remote myocardium (1157±74 vs 859±36 & 835±28 ms; both p<0.0001) with intermediate T1 values (1007±31 ms) in peri-infarct regions.
Compared with LGE, MEMRI was more sensitive in detecting dysfunctional myocardium (dysfunctional fraction 40.5±11.9 vs 34.9%±13.9%; p=0.02) & tracked more closely with abnormal wall motion (r2=0.72 vs 0.55; p<0.0001).
Kinetic modelling showed reduced myocardial manganese influx between remote, peri-infarct & infarct regions, enabling absolute discrimination of infarcted myocardium.
After 3 months, manganese uptake increased in peri-infarct regions (16.5±3.5 vs 22.8±3.5 mL/100 g/min, p<0.0001), but not the remote (23.3±2.8 vs 23.0±3.2 mL/100 g/min, p=0.8) or infarcted (11.5±3.7 vs 14.0±1.2 mL/100 g/min, p>0.1) myocardium.
Conclusions: Through visualisation of intracellular calcium handling, MEMRI accurately differentiates infarcted, stunned & viable myocardium, & correlates with myocardial dysfunction better than LGE.
MEMRI holds major promise in directly assessing myocardial viability, function & calcium handling across a range of cardiac diseases.
- Acute myocardial infarction
- Late gadolinium enhancement (LGE)
- Manganese-enhanced MRI (MEMRI)
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Featured paper: Assessment of stunned & viable myocardium using manganese-enhanced MRI.