Endogenous assessment of diffuse myocardial fibrosis in patients with T1ρ -mapping

Purpose: Recently, it was shown that a significantly higher T _1ρ is found in compact myocardial fibrosis after chronic myocardial infarction. In this study, we investigated the feasibility of native T _1ρ-mapping for the detection of diffuse myocardial fibrosis in patients with dilated cardiomyopathy (DCM). Materials and Methods: T _1ρ-mapping was performed on three explanted hearts from DCM patients at 3 Tesla (T). Histological fibrosis quantification was performed, and compared with the T _1ρ-relaxation times in the heart. Furthermore, twenty DCM patients underwent an MRI at 1.5T. Native T _1ρ-maps, native T ₁-maps, and extracellular volume (ECV)-maps were acquired. Additionally, eight healthy volunteers were scanned for reference values. Results: A significant correlation (Pearson r = 0.49; P = 0.005) was found between ex vivo T _1ρ-values and fibrosis fraction from histology. Additionally, a significantly higher T _1ρ-relaxation time (55.2 ± 2.7 ms) was found in DCM patients compared with healthy control subjects (51.5 ± 1.2 ms) (P = 0.0024). The relation between in vivo T _1ρ-values and ECV-values was significant (Pearson r = 0.66). No significant relation was found between native T ₁- and ECV-values in this study (P = 0.89). Conclusion: This study showed proof of principle for the endogenous detection of diffuse myocardial fibrosis with T _1ρ-MRI. Ex vivo and in vivo experiments showed promising results that T _1ρ-MRI can be used to measure the extent of diffuse myocardial fibrosis in the myocardium. Level of Evidence: 2. J. Magn. Reson. Imaging 2017;45:132–138.