Interpreting a Thick Myocardium on Cardiac MR: A Practical Guide for Radiologists.

Cardiac MR (CMR) imaging plays a central role in the differential diagnosis of a thick myocardium by enabling a comprehensive assessment of myocardial morphology and tissue characteristics. Cine imaging is useful for assessing the distribution and symmetry of hypertrophy, ventricular cavity size, and focal morphological abnormalities. T1/T2 mapping and extracellular volume measurement provide a quantitative assessment of myocardial fibrosis, inflammation, and infiltration, whereas late gadolinium enhancement patterns offer qualitative visualization of disease-specific tissue injury. Strain analyses provide complementary information on early functional impairment. In this review, we propose a practical CMR-based approach for interpreting increased myocardial wall thickness using increased wall thickness as the initial imaging finding. We systematically distinguish true pathological hypertrophy from pressure-related or physiological hypertrophy, and pseudothickening. Hypertrophic cardiomyopathy, metabolic and systemic diseases, including cardiac amyloidosis, Fabry disease, uremic cardiomyopathy, and acute inflammatory phases of sarcoidosis and myocarditis, along with hypertensive heart disease, aortic stenosis, and athlete's heart, are reviewed with emphasis on their pathophysiology and characteristic CMR features. Common diagnostic pitfalls and a stepwise diagnostic algorithm applicable in routine clinical practice are also discussed.