Myocardial Fibrosis Evaluated by Diffusion-Weighted Imaging and Its Relationship to 3D Contractile Function in Patients With Hypertrophic Cardiomyopathy

Background: Previous studies have shown that diffusion-weighted imaging (DWI) is sensitive to myocardial fibrosis in ischemic and nonischemic cardiomyopathy. Purpose: To explore the prognostic value of apparent diffusion coefficient (ADC) for detecting myocardial fibrosis and its relationship to the contractile function in hypertrophic cardiomyopathy (HCM). Study Type: Prospective. Population: A total of 45 HCM patients and 20 controls. Field Strength/Sequence: 3.0T cardiac MRI. The cardiac MR sequences included cine, T-1 mapping, and DWI. Assessment: According to the presence of late gadolinium enhancement (LGE) and the extracellular volume (ECV) values (+2 SD of control subjects), respectively, reader W and reader J assessed the value of ADC of each segment for detecting myocardial fibrosis and its relationship to impaired contractile function in HCM patients. Statistical Tests: Independent sample t-test, Pearson analysis, and intraclass correlation (ICC). Results: The value of ECV was 23.6 +/- 3.0% for control. ECV >= 29.6% and ECV < 29.6% groups were classified. ADC values in the ECV >= 29.6% group were significantly increased compared to the ECV < 29.6% group, (2.41 +/- 0.23 mu m(2)/ms vs. 2.03 +/- 0.16 mu m(2)/ms, P < 0.005). Compared to the LGE - group, ECV (32.1 +/- 2.3% vs. 29.0 +/- 2.8%, P < 0.005) and ADC (2.60 +/- 0.18 mu m(2)/ms vs. 2.10 +/- 0.07 mu m(2)/ms, P < 0.005) values were significantly increased in the LGE+group. ADC values were linearly associated with ECV values (R-2=0.65) in HCM patients. ADC values were linearly associated with circumferential and longitudinal strain (R-2=0.60, R-2=0.46), as well as circumferential, longitudinal, and radial strain rate (R-2=0.13, R-2=0.25, R-2=0.17, respectively). Data Conclusion: Contractile dysfunction in HCM is predominantly associated with ADC, which is a feasible alternative to ECV and LGE for detecting myocardial fibrosis.