Non-Gaussian Diffusion Models and T1rho Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in Rats

Background Non-Gaussian diffusion models and T(1)rho quantification may reflect the changes in tissue heterogeneity in hepatic sinusoidal obstruction syndrome (SOS). Purpose To investigate the feasibility of diffusion kurtosis imaging (DKI), stretched exponential model (SEM), and T(1)rho quantification in detecting and staging SOS in a monocrotaline (MCT)-induced rat model. Study Type Animal study. Population Thirty male Sprague-Dawley rats gavaged with MCT to induce hepatic SOS and six male rats without any intervention. Field Strength/Sequence 3.0T, DWI with five b-values (0-2000 s/mm(2)) and T(1)rho with five spin lock times (1-60 msec). Assessment MRI was performed 1 day before and 1, 3, 5, 7, and 10 days after MCT administration. The corrected apparent diffusion coefficient (D-app), kurtosis coefficient (K-app), distributed diffusion coefficient (DDC), and intravoxel water molecular diffusion heterogeneity (alpha) were calculated from the corresponding non-Gaussian diffusion model. The T(1)rho value was calculated using a monoexponential model. Specimens obtained from the six timepoints were categorized into normal liver (n = 6), early-stage (n = 16), and late-stage (n = 14) SOS in accordance with the pathological score. Statistical Tests Parametric statistical methods and receiver operating characteristic (ROC) curves were employed to determine diagnostic accuracy. Results The D-app, K-app, DDC, alpha, and T(1)rho values were correlated with pathological score with r values of -0.821, 0.726, -0.828, -0.739, and 0.714 (all P < 0.001), respectively. DKI (combined D-app and K-app) and SEM (combined DDC and alpha) were better than T(1)rho for staging SOS. The areas under the ROC curve of DKI, SEM, and T(1)rho for differentiating normal liver and early-stage SOS were 0.97, 1.00, and 0.79, whereas those of DKI, SEM, and T(1)rho for differentiating early-stage and late-stage SOS were 1.00, 0.97, and 0.92, respectively. Data Conclusion DKI, SEM, and T(1)rho may be helpful in staging SOS. Level of Evidence 2 Technical Efficacy Stage 2