Histological validation of cardiac magnetic resonance T 1 mapping for detecting diffuse myocardial fibrosis in diabetic rabbits

Purpose To pathologically verify the correlation between native T1 mapping, postcontrast T1 mapping, and extracellular volume fraction (ECV) and myocardial diffuse fibrosis, as determined by collagen volume fraction (CVF). Materials and Methods Thirty New Zealand white rabbits were randomly divided into the control group (n = 6), diabetes 3 months group (n = 8), diabetes 6 months group (n = 8), and diabetes 9 months group (n = 8). All the rabbits underwent clinical 3.0T magnetic resonance (MR) examinations with pre- and postcontrast modified Look–Locker inversion recovery T1 mapping. For the histological study, each rabbit was sacrificed after MR scanning, hematoxylin and eosin and Masson staining of the left ventricular myocardium were performed, and CVF was calculated. Pre- and postcontrast T1 values and ECV were compared to CVF using Pearson's correlation coefficients. Results Two rabbits died in each diabetes group, thus each group included six rabbits. ECV calculated from pre- and postcontrast T1 values showed a very strong correlation with CVF (r = 0.876, P < 0.001), whereas postcontrast T1 values exhibited a moderate correlation with CVF (r = –0.564, P = 0.004). In contrast, precontrast T1 values showed no correlation with CVF (r = 0.311, P = 0.139). Conclusion ECV has a very strong correlation with pathological CVF, and can be used to assess the degree of diffuse myocardial fibrosis better than the postcontrast T1 value. Precontrast T1 value has no significant correlation with diffuse myocardial fibrosis. J. Magn. Reson. Imaging 2016;44:1179–1185.