Cardiac MRI Explained: Late Gadolinium, T1/T2 Mapping and Cardiomyopathy
Cardiac MRI is the reference standard for heart tissue characterisation. Learn LGE, T1/T2 mapping and when it changes management.
Cardiac MRI (CMR) is the reference standard for heart tissue characterisation and precise chamber measurement. Its unique strength is late gadolinium enhancement (LGE) which reveals scar or fibrosis, plus T1/T2 mapping quantifying oedema, fat, and iron. It is essential in unexplained cardiomyopathy, myocarditis, viability assessment, and iron overload.
CMR combines high-resolution anatomy with multi-parametric tissue characterisation that echocardiography cannot match. Cine sequences give reference-standard ejection fraction and volumes (± 3% reproducibility). LGE identifies subendocardial (ischaemic) or mid-wall/epicardial (non-ischaemic) scar patterns — helping distinguish infarct, myocarditis, sarcoidosis, HCM, and amyloidosis. T1 mapping detects diffuse fibrosis, oedema, fat, iron, and amyloid. T2 mapping quantifies oedema (acute inflammation). Lake Louise criteria (updated 2018) diagnose myocarditis: increased T2, increased native T1 or ECV, and LGE. CMR is now class I recommendation in ESC HCM guidelines for phenotyping; in unexplained heart failure it changes diagnosis in 30–40% of cases (SCMR whitepapers). Cardiac iron: T2* < 20 ms suggests iron overload (thalassaemia). Contraindications: non-conditional pacemakers/ICDs (increasingly conditional), severe claustrophobia. Gadolinium: caution in eGFR < 30. Emerging: 4D flow MRI, stress perfusion CMR (competitive with SPECT for ischaemia detection).
- Radiation
- None
- Reference standard
- Chamber volumes + EF
- Unique feature
- LGE (scar) + T1/T2 mapping
- Myocarditis criteria
- Lake Louise (updated 2018)
- Iron overload
- T2* < 20 ms
LGE patterns + causes
| Pattern | Suggests |
|---|---|
| Subendocardial / transmural in coronary territory | Ischaemic scar (previous MI) |
| Mid-wall / epicardial | Non-ischaemic (myocarditis, DCM, sarcoid) |
| Diffuse subendocardial + short T1 | Cardiac amyloid |
| RV insertion points | Pulmonary hypertension |
| Focal patchy epicardial | Sarcoidosis |
Key indications
Unexplained heart failure or dilated cardiomyopathy.
Suspected myocarditis or cardiac sarcoid.
HCM phenotyping and sudden cardiac death risk stratification (fibrosis burden).
Viability assessment before revascularisation.
Cardiac amyloidosis workup.
Iron overload monitoring (thalassaemia, transfusion-dependent).
- CMR suggests active myocarditis + arrhythmia — cardiology admission.
- HCM + LGE burden > 15% — enhanced SCD risk stratification.
- Cardiac amyloid — refer for haematology + amyloid MDT.
When CMR changes management
- 1Unexplained cardiomyopathy?CMR to phenotype.
- 2Suspected myocarditis?CMR with Lake Louise criteria.
- 3HCM SCD risk unclear?CMR for LGE burden.
- 4Iron overload risk?Cardiac T2*.
Related questions people ask
Frequently asked questions
- CMR gives unmatched tissue characterisation.
- LGE identifies scar patterns.
- T1/T2 mapping quantifies oedema, fat, iron, amyloid.
- Lake Louise criteria diagnose myocarditis.
- Class I ESC recommendation in HCM phenotyping.
References
2 sources- SCMRCardiovascular Magnetic Resonance Recommendations
US/international CMR society.
scmr.org
- ESC HCM Guidelines 2023
European cardiology.
academic.oup.com
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