What are the indications for cardiac MRI (Magnetic Resonance Imaging)?

Indications for Cardiac MRI

Cardiac MRI is strongly indicated for the evaluation of hypertrophic cardiomyopathy, pericardial disease, myocardial tissue characterization, and assessment of structural heart disease in patients with arrhythmias. 1

Primary Indications by Condition

Hypertrophic Cardiomyopathy (HCM)

• First-line diagnostic tool when:
  • Echocardiographic windows are inadequate (Class I, Level of Evidence B) 1
  • Excluding infiltrative processes (Class IIa, Level of Evidence B) 1
  • Evaluating apical hypertrophy and aneurysms (Class IIa, Level of Evidence B) 1
  • Assessing extent and distribution of myocardial fibrosis prior to septal alcohol ablation or myectomy (Class IIb, Level of Evidence C) 1

Pericardial Disease

• Strongly recommended as second-level testing for:
  • Diagnostic workup in pericarditis (Class I, Level of Evidence C) 1
  • Diagnosis of constrictive pericarditis (Class I, Level of Evidence C) 1
  • Evaluation of pericardial effusion (Class IIa, Level of Evidence C) 1

Arrhythmias and Sudden Cardiac Death

• Indicated for:
  • Investigation of structural heart disease in patients with ventricular arrhythmias (Class I) 1
  • Risk stratification for sudden cardiac death 1
  • Evaluation of survivors of sudden cardiac death 1
  • Assessment prior to implantable cardioverter-defibrillator placement in dilated cardiomyopathy 1
  • Evaluation of patients with neuromuscular disorders at risk for cardiac involvement 1

Heart Failure

• Recommended for:
  • Myocardial tissue characterization in suspected inflammatory or infiltrative diseases (e.g., myocarditis, amyloidosis) (Class I) 1
  • Distinguishing between ischemic and non-ischemic myocardial damage (Class IIa) 1
  • Assessment of myocardial scarring and fibrosis (Class IIa) 1

Restrictive Cardiomyopathy

• Indicated for:
  • Accurate assessment of cardiac chambers volume and mass 1
  • Myocardial tissue characterization 1
  • T1 and T2* mapping for infiltrative cardiomyopathies and iron overload 1

Technical Capabilities and Clinical Value

Tissue Characterization

• Late gadolinium enhancement (LGE) for:
  • Identification of myocardial fibrosis 2
  • Determination of underlying etiology of heart failure 2
  • Prognostic assessment in non-ischemic cardiomyopathies 2

Functional Assessment

• Reference standard for quantifying:
  • Chamber size and volumes 2
  • Ejection fraction 2
  • Regional wall motion abnormalities 2

Advanced Techniques

• T1 mapping (native and with extracellular volume fraction)
• T2 mapping for edema assessment
• T2* mapping for iron quantification
• Tagging for myocardial strain assessment 3

Comparative Diagnostic Value

Cardiac MRI has demonstrated excellent diagnostic capability for patients with heart failure, with sensitivity comparable to or better than endomyocardial biopsy for many conditions 4:

• Superior sensitivity for cardiac sarcoidosis compared to endomyocardial biopsy
• Greater specificity for dilated cardiomyopathy than endomyocardial biopsy
• Better sensitivity for hypertensive heart disease
• Excellent sensitivity (100%) for apical and obstructive HCM 4

Important Clinical Considerations

When to Choose CMR Over Other Modalities

• When tissue characterization is needed
• When accurate quantification of ventricular volumes and function is required
• When echocardiography is inconclusive or limited by poor acoustic windows
• For risk stratification in cardiomyopathies

Limitations and Contraindications

• Patients with certain implanted devices (though many newer devices are MRI-conditional)
• Severe claustrophobia
• Severe renal dysfunction (GFR <30 mL/min) when gadolinium contrast is needed
• Inability to perform adequate breath-holds (though newer sequences can mitigate this)

Emerging Applications

Recent guidelines show an increasing trend in cardiac MRI recommendations, with both ESC and ACC/AHA guidelines expanding their recommendations over time (+73% for ESC 2017-2023 and +38% for ACC/AHA 2016-2023) 1. This reflects growing recognition of cardiac MRI's value in:

• Congenital heart disease evaluation
• Pre-procedural planning for structural interventions
• Quantitative assessment of disease severity using mapping techniques
• Monitoring disease progression and treatment response

By providing comprehensive anatomical, functional, and tissue characterization information in a single examination, cardiac MRI has become an essential tool in the diagnostic algorithm for cardiovascular diseases, particularly for conditions where tissue characterization is crucial for diagnosis, risk stratification, and management decisions.