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

Figures

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  Fig. 1. Cardiac MRI findings of septal hypertrophic cardiomyopathy. A. On the short-axis cine image at end-diastole, the mid-anteroseptal wall (arrow) is markedly thickened, measuring 21 mm. B. Late gadolinium enhancement imaging reveals patchy enhancement (arrow) at the midwall of the thickened myocardium and at the anterior and inferior right ventricle insertion points. C-E. The native and post-contrast T1 maps and ECV map show high native T1 (up to 1,328 ms), low post-contrast T1 values, and high ECV values (29.2%) respectively, within the thickened myocardium (arrows) on 3T MRI. F. T2 mapping shows no significant T2 elevation, with values up to 42 ms on 3T MRI. ECV = extracellular volume fraction

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  Fig. 2. Cardiac MRI findings of apical hypertrophic cardiomyopathy. A, B. The three-chamber and short-axis cine images at end-diastole reveal a spade-shaped left ventricular cavity due to apical wall thickening (arrows), measuring 17 mm. C. No significant late gadolinium enhancement is observed in the thickened apical myocardium (arrows). D, E. The native and post-contrast T1 maps show higher native T1 values (up to 1,317 ms) and lower post T1 values, respectively, at the thickened myocardium on 3T MRI. F. The T2 map shows T2 values of the thickened myocardium within the normal range, measuring up to 40 ms on 3T MRI.

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  Fig. 3. Cardiac MRI findings of concentric hypertrophic cardiomyopathy. A. The four-chamber cine image of end-diastole shows diffuse concentric thickening of the global left ventricular wall (end-diastolic volume index: 69.2 mL/m2, left ventricular mass index: 162 g/m2). B. Diffuse midwall patchy enhancement is noted on the short-axis late gadolinium enhancement image. C. On the native T1 map, significantly higher T1 values (up to 1,348 ms) are noted.

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  Fig. 4. Cardiac MRI findings of immunoglobulin light-chain amyloidosis. A. Four-chamber cine image of end-diastolic phase shows diffuse LV, RV, and bi-atrial wall thickening and pericardial and bilateral pleural effusion. B. The late gadolinium enhancement image reveals diffuse circumferential LV and RV subendocardial hyperenhancement with diffuse enhancement of bi-atrial wall. C. The native T1 map shows diffusely increased native T1 values (up to 1,482 ms) in the myocardium. D. The myocardium demonstrates low subendocardial post-T1 values in the LV. E. The ECV polar map shows increased ECV values in the global LV wall. F. The T2 map shows diffusely increased T2 values in the myocardium, measuring up to 59 ms. G. LV radial and circumferential strain polar maps reveal characteristic apical sparing patterns. ECV = extracellular volume fraction, LV = left ventricle, RV = right ventricle

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  Fig. 5. Cardiac MRI findings of Fabry disease. A, B. The three-chamber and basal short-axis late gadolinium enhancement images show focal hyperenhancement in the basal inferolateral LV wall with underlying concentric LV wall thickening (arrows). C. The native T1 map demonstrates significantly decreased T1 values (943–1,232 ms) at the basal level of the LV wall. LV = left ventricle

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  Fig. 6. Cardiac MRI findings of acute inflammatory phase of sarcoidosis. A, B. On the short-axis cine image of end-diastole, basal septal wall thickening (arrows, A) is noted, measuring up to 18 mm with midwall or transmural enhancement (arrows, B) on the LGE image. C, D. The T1 maps show increased native T1 values (up to 1,411 ms) and significantly decreased post T1 values on 3T MRI, corresponding to the LGE area (arrows). E. The ECV map shows increased ECV values (30.8%, arrows). F. The T2 map shows heterogeneously increased myocardial T2 values (arrows). G. The 18F-labeled fluorodeoxyglucose PET-CT suggests active inflammation at the basal to mid-septal LV wall (arrow). ECV = extracellular volume fraction, LGE = late gadolinium enhancement, LV = left ventricle

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  Fig. 7. Cardiac MRI findings of acute myocarditis. A. The basal short-axis T2-weighted image shows linear subepicardial T2 high-signal intensity at the mildly thickened inferior and inferolateral walls (arrows). B. The late gadolinium-enhanced image shows hyperenhancement in the corresponding area (arrows).

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  Fig. 8. Cardiac MRI findings of hypertensive heart disease. A. The basal short-axis cine image at end-diastole shows diffuse concentric thickening of the left ventricular wall (end-diastolic volume index: 83.0 mL/m2, left ventricular mass index: 132 g/m2). B. An ill-defined midwall and subepicardial patchy enhancement near the inferior right ventricle insertion site (arrow) is noted on the short-axis late gadolinium enhancement image. C. The ECV map demonstrates mildly increased ECV (27.7%) in the corresponding region (arrow). ECV = extracellular volume fraction

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  Fig. 9. Cardiac MRI findings of aortic stenosis-related pressure overload. A-C. The four-chamber and short-axis cine images of the end-diastole demonstrate basal to mid-septal wall thickening (arrows, A and B) with focal enhancement at anterior RV insertion site (arrow) on the late gadolinium enhancement image (C). D, E. On the native T1 and ECV maps, focal increases in T1 and ECV values are noted at the anterior RV insertion site (arrows) at the mid-level of the LV wall. F. The three-chamber cine image at the systolic phase shows aortic valve jet flow (arrows) suggesting aortic stenosis. ECV = extracellular volume fraction, RV = right ventricle

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  Fig. 10. Cardiac MRI findings of apical hypertrophy mimicked by apically displaced papillary muscles. A-C. On the short-axis cine image (A) of the end-diastole, the apical lateral and inferior wall (arrows) is suspicious for abnormal thickening. However, the upper apical short-axis and two-chamber cine images (B, C) demonstrate a preserved apical myocardium, with anterior and posterior papillary muscles (arrows) inserted near left ventricular apex, mimicking apical hypertrophic cardiomyopathy. D, E. The apical T1 and T2 maps reveal normal T1 (<1,285 ms) and T2 (<43 ms) values at the apical lateral and inferior wall.

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  Fig. 11. Diagnostic approach for a thick myocardium on cardiac MRI. This flowchart illustrates a stepwise diagnostic strategy, beginning with the distinction between true myocardial thickening and pseudothickening. Subsequent differentiation is guided by the characteristic combinations of LVH patterns, clinical context, and CMR tissue characterization, including the mapping of parameters and LGE distribution. This approach guides the differentiation between physiological thickening, hypertrophic cardiomyopathy phenotypes, metabolic/systemic cardiomyopathies, pressure-related thickening, and acute inflammatory conditions. Changes in mapping values are expressed as relative trends rather than absolute cutoff values, acknowledging inter-scanner and inter-vendor variabilities. AV = aortic valve, CMR = cardiac MR, ECV = extracellular volume fraction, LGE = late gadolinium enhancement, LV = left ventricle, LVH = left ventricular hypertrophy