Evaluation of diffuse myocardial fibrosis of cardiomyopathy by using T1 mapping: initial study

Objective: To investigate the value of contrast enhancement T₁ mapping in detection of diffuse myocardial fibrosis in cardiomyopathy, and the relationship between myocardial fibrosis and cardiac function. Methods: From September 2013 to September 2014, 76 cases of cardiomyopathy patients (including myocarditis) and 33 cases of healthy controls were enrolled in our study. All the subjects underwent cardiac MR (CMR) examination. Scan sequences included cine MR, pre-contrast and post-contrast T₁ mapping and late gadolinium enhancement (LGE) imaging. The pre-/post-contrast left ventricle average T₁ value and cardiac function of patients and controls were measured and compared by using independent-samples t test. According to the LGE imaging, all the subjects were subsequently divided into LGE positive group, LGE negative group and control group. The myocardial average T₁ value and cardiac function among the three sub-groups were compared by using one-way ANOVA, and the relationship among them were analyzed by using Pearson correlation. Results: Among the 76 cases of non-ischemia cardiomyopathy patients, 51 cases (67.1%) had LGE. Compared with controls, cardiomyopathy patients presented with higher pre-contrast T₁ value [(1306.4 ± 84.6) ms vs. (1266.6 ± 57.3) ms, t = 2.10, P < 0.05] and lower post-contrast T₁ value [(483.6 ± 112.0) ms vs. (534.1 ± 92.7) ms, -0.27, P < 0.05]. Pre-contrast and post-contrast average T₁ value of LGE positive patients were (1322.2 ± 85.8) and (459.7 ± 132.2) ms respectively; pre-contrast and post-contrast average T₁ value of LGE negative patients were (1267.0 ± 68.5) ms and (521.0 ± 95.2) ms, there were statistical significant differences of T₁ value between LGE positive and LGE negative patients (P < 0.01), however, there were no statistical significant differences of T₁ value between LGE negative patients and controls (P > 0.05). There were correlation between pre-/post-contrast left ventricle T₁ value and ejection fraction (EF) in cardiomyopathy patients (r = - 0.252, -0.217, P < 0.01), however no statistical correlation with other cardiac function parameters (P > 0.05). Conclusions: The average pre-/ post-contrast T₁ value in left ventricle myocardium are helpful for detection of diffuse fibrosis in cardiomyopathy patients. The LGE positive is a sign that can greatly change the T₁ value of the myocardial tissue, meanwhile, myocardial fibrosis is negative correlated with ejection fraction in cardiomyopathy patients. (authors)