Spatially Constrained Incoherent Motion (SCIM) Model Improves Quantitative Diffusion-Weighted MRI Analysis of Crohn's Disease Patients

Quantitative analysis of fast and slow diffusion from abdominal Diffusion-weighted MRI has the potential to provide important new insights into physiological and microstructural properties of the body. However, the commonly used, independent voxel-wise fitting of the signal decay model leads to imprecise parameter estimates, which has hampered their practical usage. In this work we evaluated the improvement in the precision of the fast and slow diffusion parameter estimates achieved by using a spatially-constrained Incoherent Motion (SCIM) model of DW-MRI signal decay in 5 healthy subjects and 24 Crohn’s disease patients. We found that the improvement in Coefficient of Variation (CV) of the parameter estimates achieved using the SCIM model was significantly larger compared to thus achieved by repeated acquisition and signal averaging (n=5, paired Student’s t-test, p ≤ 0.05). We also found that the SCIM model reduced the coefficient of variation of the parameter estimates of the D∗ and f parameter estimates in the ileum by 30% compared to the independent voxel-wise fitting of the signal decay model in the Crohn’s patients data (n=24, paired Student’s t-test, p ≤ 0.05). The SCIM model is more precise for quantitative analysis of abdominal DW-MRI signal decay.