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What is CMR

Cardiac magnetic resonance (CMR)

The cornerstone of modern cardiology: a single test that studies the heart’s anatomy, function and tissue, without ionising radiation.

INCIC cases →INCIC technique

From recognising patterns to identifying causes

For decades, cardiology classified heart disease by how the heart looked: a dilated heart, a thickened heart. These are phenotypes, and the same phenotype can hide very different causes.

CMR changed that logic. By characterising myocardial tissue, it helps move from describing the pattern to finding the cause: a thickened heart may be due to Fabry disease or to sarcomeric hypertrophic cardiomyopathy, and telling them apart changes the work-up, the treatment and the advice to the family.

That is why CMR has become the cornerstone of modern cardiology and the beacon guiding its new paradigm: precision cardiology.

What is it?

Cardiac magnetic resonance uses a strong magnetic field and radio waves, not X-rays. It acquires images of the beating heart synchronised with the electrocardiogram and can characterise the heart muscle tissue.

That is why it is used to measure chamber size and function, and to look for oedema, fibrosis, scar or infiltration of the myocardium when other tests are not enough.

What does it assess?

Function and volumes

Cine sequences to measure volumes, mass and ejection fraction of both ventricles.

Tissue characterisation

Late gadolinium enhancement and T1, T2 and extracellular volume mapping to detect scar, fibrosis, oedema or infiltration.

Perfusion and viability

Rest and stress perfusion to assess ischaemia, and late enhancement to estimate myocardial viability.

Flow

Flow measurements, including 4D flow, to quantify valve disease and shunts.

When is it indicated?

Scientific societies recognise its value in, among others:

  • Cardiomyopathies: hypertrophic, dilated, arrhythmogenic and infiltrative such as amyloidosis.
  • Suspected myocarditis and other myocardial inflammation.
  • Ischaemic heart disease: infarction, ischaemia and viability.
  • Valve disease and aortic disease.
  • Congenital heart disease.
  • Cardiac masses and pericardial disease.

Whether a patient needs CMR, and which protocol to use, is decided by their treating physician.

What is the test like?

  • The person lies in the scanner with electrocardiogram electrodes on the chest.
  • Breath-holds of a few seconds are requested to obtain sharp images.
  • Many studies use an intravenous gadolinium-based contrast agent.
  • Duration depends on the protocol; it is usually 30 to 60 minutes.
  • The scanner is noisy; the centre provides hearing protection.

Safety: what to mention beforehand

  • Pacemakers, defibrillators or other devices: many allow MRI under specific conditions, but they must be assessed first.
  • Metal implants, clips, prostheses or metal fragments.
  • Kidney disease, because of gadolinium-based contrast.
  • Pregnancy, allergy to contrast agents or claustrophobia.

Always follow the instructions of the centre where the test is performed.

CMR at INCIC

Cardiologists and radiologists dedicated to advanced cardiac imaging since 2020. We organised the first SCMR-endorsed course in Chile and share cases, technique and literature with colleagues across Chile and Latin America.

INCIC cases →

Short video cases to test your diagnosis.

INCIC technique →

Acquisition tips for better studies.

CMR highlights →

The most relevant papers each week.

Training →

CMR fellowship and SCMR competency levels.

Publications →

The team’s scientific output.

Team →

The institute’s specialists.

Have a question?

Write to us about courses, collaboration or general information about CMR.

Contact INCIC →

General educational information. It does not replace assessment by a physician.

Sources

  1. Leiner T, et al. SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2020;22:76. doi:10.1186/s12968-020-00682-4
  2. Kramer CM, et al. Standardized cardiovascular magnetic resonance imaging (CMR) protocols: 2020 update. J Cardiovasc Magn Reson 2020;22:17. doi:10.1186/s12968-020-00607-1
  3. Arbelo E, et al. 2023 ESC Guidelines for the management of cardiomyopathies. Eur Heart J 2023;44:3503-3626. doi:10.1093/eurheartj/ehad194
  4. Ferreira VM, et al. Cardiovascular magnetic resonance in nonischemic myocardial inflammation: expert recommendations. J Am Coll Cardiol 2018;72:3158-3176. doi:10.1016/j.jacc.2018.09.072
  5. Indik JH, et al. 2017 HRS expert consensus statement on magnetic resonance imaging and radiation exposure in patients with cardiovascular implantable electronic devices. Heart Rhythm 2017;14:e97-e153. doi:10.1016/j.hrthm.2017.04.025
  6. Weinreb JC, et al. Use of intravenous gadolinium-based contrast media in patients with kidney disease: consensus statements from the ACR and the National Kidney Foundation. Radiology 2021;298:28-35. doi:10.1148/radiol.2020202903