MRI-LGE Extent (% LV Mass Fibrosis) Calculator
- MRI-LGE Extent (% LV Mass Fibrosis): Comprehensive Explanation and Clinical Context
This calculator estimates the proportion of myocardial fibrosis (late gadolinium enhancement, LGE) relative to total left ventricular (LV) mass using cardiac MRI data: %LGE = (LGE mass / LV mass) × 100.
When input volumes are provided, they are converted to grams assuming a myocardial density of 1.05 g/mL. LGE reflects focal myocardial scar or fibrosis and is a powerful prognostic marker across cardiomyopathies.
In hypertrophic cardiomyopathy (HCM), the presence of extensive LGE (≥15% of LV mass) is a major risk modifier for sudden cardiac death, guiding ICD consideration. In ischemic heart disease, infarct size >30% LV mass predicts adverse remodeling and increased mortality, while smaller infarcts carry better prognosis. In dilated/non-ischemic cardiomyopathy (DCM/NICM), the presence (rather than exact % extent) of LGE, especially mid-wall, predicts arrhythmia and mortality, though standardized thresholds are lacking.
Overall, LGE quantification refines risk stratification and complements functional and clinical assessment in precision cardiology.
References:
1. Ommen SR et al. AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy. Circulation. 2024;149:e331–e423. doi:10.1161/CIR.0000000000001250.
2. Wozniak M et al. How to assess sudden cardiac death risk in hypertrophic cardiomyopathy. Polish Heart Journal. 2024.
3. Gräni C et al. Extensive LGE and outcome prediction in HCM. JACC. 2020;75(3):274–286.
4. Kim RJ et al. Infarct quantification with cardiovascular magnetic resonance: methodology and clinical relevance. Circulation. 2022.
5. Assumptions for myocardial density: 1.05 g/mL (CMR Quantification Standards, SCMR, 2023).
6. Gulati A et al. Prognostic value of LGE in non-ischemic cardiomyopathy. JACC. 2013;61:895–904.
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