Feasibility of T1 mapping with histogram analysis for the diagnosis and staging of liver fibrosis: Preclinical results

Purpose: To compare the diagnostic accuracy of parameters derived from the histogram analysis of precontrast, 10-min hepatobiliary phase (HBP) and 20-min HBP T1 maps for staging liver fibrosis (LF). Methods: LF was induced in New Zealand white rabbits by subcutaneous injections of carbon tetrachloride for 4-16 weeks (n = 120), and 20 rabbits injected with saline served as controls. Precontrast, 10-min and 20-min HBP modified Look-Locker inversion recovery (MOLLI) T1 mapping was performed. Histogram analysis of T1 maps was performed, and the mean, median, skewness, kurtosis, entropy, inhomogeneity and 10th/25th/75th/ 90th percentiles of T1(native), T1(10min) and T1(20min) were derived. Quantitative histogram parameters were compared. For significant parameters, further receiver operating characteristic (ROC) analyses were performed to evaluate the potential diagnostic performance in differentiating LF stages. Results: Finally, 17, 20, 21, 21 and 20 rabbits were included for the F0, F1, F2, F3, and F4 pathological grades of fibrosis, respectively. The mean/75th of T1(native), entropy of T1(10min) and entropy/mean/median/10th of T1(20min) demonstrated a significant good correlation with the LF stage (vertical bar r vertical bar = 0.543-0.866, all P < 0.05). The 75th of T1(native), entropy(10min), and entropy(20min) were the three most reliable imaging markers in reflecting the stage of LF. The area under the ROC curve of entropy(20min) was larger than that of entropy(10min) (P < 0.05 for LF >= F2, >= F3, and >= F4) and the 75th of T1(native) (P < 0.05 for LF >= F2 and >= F3) for staging LF. Conclusion: Magnetic resonance histogram analysis of T1 maps, particularly the entropy derived from 20-min HBP T1 mapping, is promising for predicting the LF stage.