Cardiac MRI (CMR)
The reference standard for myocardial tissue characterisation — CMR shows not just how the heart moves, but what the muscle is made of.
What CMR shows
Cardiac MRI combines several acquisitions in one study: cine imaging for function, late gadolinium enhancement (LGE) for scar, mapping for diffuse disease, and phase-contrast for flow. It is uniquely able to distinguish patterns of myocardial injury non-invasively.
- Function & volumes: cine SSFP gives the most reproducible ejection fraction and chamber volumes — the gold standard for serial follow-up.
- Viability & scar (LGE): subendocardial/transmural LGE in a coronary territory indicates infarct; the transmurality predicts recovery after revascularisation.
- Non-ischaemic patterns: mid-wall or epicardial LGE points away from coronary disease — e.g. myocarditis, sarcoid, dilated or hypertrophic cardiomyopathy.
Key indications
| Question | What CMR adds |
|---|---|
| Viability before revascularisation | LGE transmurality predicts functional recovery |
| Myocarditis | Oedema (T2) + non-ischaemic LGE (updated Lake Louise criteria) |
| Cardiomyopathy workup | Phenotype + fibrosis pattern; risk stratification |
| Infiltration / storage | T1/ECV (amyloid, fibrosis), T2* (iron overload) |
| Congenital / valve / shunt | Phase-contrast flow, Qp:Qs quantification |
Practical notes
CMR needs breath-holds and ECG gating, so rhythm and cooperation affect quality. Gadolinium is used for LGE; check renal function. For device patients, confirm MR-conditional status — see the Implant Safety Checker.
Reference: Ferreira VM et al. Cardiac MRI in myocardial inflammation: expert recommendations (updated Lake Louise Criteria). J Am Coll Cardiol 2018;72:3158–76. Messroghli DR et al. JCMR 2017;19:75.
Educational summary for clinicians; indications and protocols vary by centre and guideline. Not medical advice.