Identify fracture-critical regions inside the proximal femur using statistical parametric mapping. Li W, Kornak J, Harris T, Keyak J, Li C, Lu Y, Cheng X, Lang T. Bone. 2009 Apr;44(4):596-602. Epub 2008 Dec 24.
The overall aim of our group is to develop and employ quantitative imaging methods to better understand the human biology of the musculoskeletal system. This overall aim enfolds multiple objectives:
- To better our understanding of how age affects muscle and bone tissue and how such age-related changes affect risk of negative health outcomes such as falls, fractures and mobility limitations in the elderly population.
- To better understand the relationship between load bearing and the morphology and function of muscle and bone tissue.
- To better our understanding of how drug therapies modify musculoskeletal tissues, shedding light on the mechanisms by which such therapies affect health outcomes.
Computed tomographic assessment of bone structure: Over the last ten years we have developed and brought to clinical practice computer algorithms to quantify, from x-ray computed tomography images, fracture-related physical properties of the vertebrae and hips, such as trabecular and cortical bone mineral density, measures of bone size such as cross-sectional area and tissue volume and estimates of bending and axial rigidity. This methodology has been employed in many studies, including small-scale studies within our own group and with external collaborators at UCSF and elsewhere. This methodology has also been employed in ground-breaking epidemiologic studies such as AGES-R and Mr Os as well as in important multi-center pharmaceutical studies. This technique has been employed to characterize the roles of bone density and structure as hip fracture predictors, to understand the effect of long-duration spaceflight on the skeleton and to study the effect of anabolic drug therapies such as parathyroid hormone on bone structure.
Finite-element modeling of the hip: Finite element modeling is a technique employed by engineers to model the strength of structures, such as bridges, airplane wings, or car parts, to understand the risk of failure of those structures under load-bearing conditions. Dr Joyce Keyak (see collaborators) has developed a technique to generate finite element models of the hip from CT scans. We are collaborating with Dr Keyak on various projects to examine the effect of age-related changes, spaceflight and drug therapies on the strength of the hip and the hip fracture.
Muscle imaging: Muscle weakness is a major risk factor for various forms of disability in the elderly population, including falls and mobility limitations. Recently, we have shown that CT-derived muscle cross-sectional area and Hounsfield unit (a measure of x-ray attenuation related to the infiltration of muscle tissue by fat) are independent predictors of hip fracture, acting as surrogates for reduced muscle strength. In the near future, we expect quantitative muscle imaging to be an increasingly important part of our research program.
Application of advanced neuro-image processing techniques to bone studies: We are developing voxel-based morphometry (VBM) a technique widely used in neuro-imaging studies, to the study of bone. This approach provides a novel means of visualizing and quantifying 3D bone structure, allowing for insight into how bone remodeling processes redistribute bone mineral in relation to aging, changes in physical activity and drug therapies.
Our research is funded by NIH, NASA and by pharmaceutical companies.