MRI of restrictive cardiomyopathy

Abstract

Objective To evaluate the diagnostic value of MRI in combination of delayed gadolinium-enhanced MR imaging for the identification of restrictive cardiomyopathy (RCM). Methods One hundred sixteen patients with RCM underwent ECG, thoracic radiography, echocardiography and MRI. The final diagnosis was made on comprehensive evaluation in consideration of patient history, clinical symptoms and imaging appearances. Fifty-five normal subjects were used as the controls. All patients were divided into two groups according to contrast-enhanced MRI patterns: RCM with delayed enhancement (RCM with DE, n = 35) and RCM without delayed enhancement (RCM without DE, n = 81). Bi-atrial and bi-ventricular size, ventricular septal and left free wall thickness were measured. A paired t-test was used for statistic analysis. Results Bi-atrial size, right ventricular diastolic diameter (RVDD), ventricular septal and left free wall thickness were significantly larger in RCM patients than in normal subjects (P <0. 05).The parameters measured were as follows: (49.89 ± 13.75) and (28.78 ± 6. 31) mm, (83. 13 ± 18.07) and (57.71 ± 9.50) mm, (64.66 ± 15.87) and (38. 11 ± 6. 17) mm, (63.55 ± 16.05) and (41.57 ± 7.90) mm,(13.03±4.27)and(9.80±2.46) mm, (10. 19±3. 18) and (7.59±2.78) mm, (39.53 ± 7.90)and (36. 17 ± 5.88) mm There was no statistical difference between the two groups [(47.81 ± 8.66) mm] and [(48. 63 ± 6. 26) mm] in left ventricular diastolic diameter (LVDD, P 0. 05). Visual observation showed mild mitral regurgitation (50 cases), moderate mitral regurgitation (24 cases), mild tricuspid regurgitation (32 cases) and severe tricuspid regurgitation (46 cases). Thirty-five RCMs with DE presented diffuse (15 cases) or segmental (20 cases) enhancement. Twelve RCMs with diffuse delayed enhancement showed powdery enhancement, and 3 showed petaline enhancement. Three cases with powdery enhancement were histologically proven as myocardial amyloidosis. Ventricular septum was the most vulnerable segment in patients with segmental enhancement. Six cases presented subendocardial enhancement that corresponded to apical obliteration, of which one case was confirmed as hypercosinophilia by bone marrow biopsy and the other 14 cases didn't present any regular enhancement. In 81 RCMs without DE, marked hi-atrial dilation, near-normal ventricular chambers and near-normal ventricular thickness were presented. Conclusion MRI is an excellent imaging modality for the diagnosis of restrictive cardiomyopathy. Key words: Cardiomyopathy; restrictive; Magnetic resonance imaging; Image enhancement