MAGNETIC RESONANCE IMAGING OF PROXIMAL FEMUR AND SURROUNDING MUSCLES: IN VIVO PRECISION

Abstract

Background: Hip fractures are a major health problem in Canada, and two main contributors to hip fracture are weak bone strength and fall. Weak muscles also negatively affect bone strength and increase the likelihood of falling. Advanced imaging techniques, such as magnetic resonance imaging (MRI), offer in vivo measurement of bone strength and muscle area at the proximal femur. However, it is not known if MRI-based measurements of bone and muscle properties are repeatable (i.e. precise). Methods: The femoral neck and shaft of 14 healthy participants were scanned three times, using a 1.5T MRI with repositioning between scans. Boundaries of the femoral neck, shaft and four muscle groups were delineated semi-automatically. Geometrical and strength properties of bone and area of muscle groups were determined based on segmented images. The short-term precision errors (root mean square coefficient of variation; CVrms%) between the repeated measures were calculated accordingly. Results: MRI-based measures of bone geometry and strength and muscle area at the proximal femur demonstrated in vivo precision errors < 7.6%. The average CVrms% for bone measures and muscle area were less than 4% and 2.5% respectively. Higher CVrms% (e.g. average: 4.8%) was obtained for bone strength properties. Conclusion: This is the first study to evaluate the in vivo performance of MRI on application to the proximal femur and surrounding muscles. Results demonstrate that MRI is a promising non-ionizing technique that offers precise measures of bone and muscle at the proximal femur.