Comparative Study of Imaging and Pathology of Sacroiliac Joint in Normal Rats Based on IVIM-DWI and DCE-MRI

Abstract

Background : There are few reports describing the relationship between functional MRI findings and pathology of normal sacroiliac joint (SIJ). Furthermore, the pathology of SIJ is difficult to access, so animal models have special value. Aims:We undertook this study to explore the changes of parameters of Intravoxel Incoherent Motion Diffusion Weighted Imaging(IVIM-DWI), Dynamic Contrast Enhanced Magnetic Resonance Imaging(DCE-MRI) and compare them with pathology in the SIJ of normal rats in different ages.Methods: Thirty 7 week-old male wistar rats were included in the study. The parameters of IVIM-DWI and DCE-MRI in bone marrow and the joint space of SIJ were measured respectively at 8, 13, 18, 23, 28 and 33 weeks, then histological specimen of the SIJ were examined with light microscopy. One-way ANOVA were used for statistical analysis. Results: The values of D in the sacral and iliac bone marrow of normal rats in different age groups decreased with the increase of age, and ANOVA indicated a significant difference in D values among different age groups(P＜0.005). The normal values of D*, f, Fenh(%), Senh(%/s) in the sacral bone marrow, the iliac bone marrow and in the joint space in SIJ of normal rats were obtained. In six groups of rats with different weeks of age, the pathology of the SIJ surface was smooth and clear, the cartilage cells were intact, and no thickening or pannus formation was found. Conclusions: The range of IVIM-DWI and DCE-MRI parameters of the sacral and iliac bone marrow and of the synovial area of the joint space in normal rats were obtained. It provides a basis for further clinical study of SIJ lesions.