ASSESSMENT OF MUSCLE MICROSTRUCTURES IN OSTEOPOROTIC AND OSTEOARTHRITIC SUBJECTS BY USING MAGNETIC RESONANCE DIFFUSION TENSOR IMAGING

Objective: Aim of the study was to investigate the microstructural features in muscles of osteoporotic women by using magnetic resonance (MR) diffusion tensor imaging (DTI). We examined in vitro vastus lateralis samples of osteoporotic and osteoarthritic subjects taken during a primary total hip arthroplasty (THA) procedure at 9.4 T measuring mean diffusivity (MD), fractional anisotropy (FA), the three eigenvalues (lambda1 lambda2 lambda3) of muscles and assessing associations between DTI parameters, subjects age, subjects BMD and subjects BMI. Material and Methods: We performed vastus lateralis biopsy in 10 women with OP underwent primary THA for hip fracture, and 10 age-matched women underwent surgery for hip osteoarthritis. This study was approved by the local Ethics Committee and written informed consent was obtained. A 9.4 TMR system with a micro-imaging probe was used to investigate muscle samples stored in a 4 %-paraformaldeyde and PBS. The DTI protocol with b-values=400 and 700 s/mm2 was applied, using a PGSTE-imaging sequences. Mean values and standard deviation were obtained for each variable for osteoporotic and osteoartritic subjects. Between-group comparisons to assess group differences and Pearson correlation analysis were performed. P values<0.05 were considered statistically significant. Results: FA was significantly higher in osteoarthritic compared to osteoporotic subjects while MD, lambda2 and lambda3 were lower in osteoarthritic compared to osteoporotic subjects (P=0.039, P=0.040 P=0.022, respectively). A significant linear correlation was found between FA and BMI in osteoporotic subjects only. Conclusion: Our in vitro preliminary results highlight differences in DTI parameters between OP and OA muscles, confirming previous histological evidences encouraging further analysis of muscle microstructure investigation by MR diffusion techniques.