Non‐Gaussian Diffusion Models and T 1 rho Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in Rats

Abstract

Background Non‐Gaussian diffusion models and T₁rho 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 T₁rho 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/mm²) and T₁rho 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 (α) were calculated from the corresponding non‐Gaussian diffusion model. The T₁rho 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, α, and T₁rho 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 α) were better than T₁rho for staging SOS. The areas under the ROC curve of DKI, SEM, and T₁rho for differentiating normal liver and early‐stage SOS were 0.97, 1.00, and 0.79, whereas those of DKI, SEM, and T₁rho for differentiating early‐stage and late‐stage SOS were 1.00, 0.97, and 0.92, respectively. Data Conclusion DKI, SEM, and T₁rho may be helpful in staging SOS. Level of Evidence 2 Technical Efficacy Stage 2