Application of Micro-CT and MRI in Clinical and Preclinical Studies of Osteoporosis and Related Disorders

Abstract

Advanced imaging techniques, which are noninvasive and nondestructive, can provide structural information about bone beyond simple bone densitometry. As the mechanical competence of trabecular bone is a function of its apparent density and D distribution, assessment of D trabecular structural characteristics may improve our ability to understand the pathophysiology of osteoporosis, to test the efficacy of pharmaceutical intervention, and to estimate bone biomechanical properties. We studied ovariectomy-induced osteopenia in rats with various treatments. Micro-CT is also useful for studying osteoporosis in mice and phenotypes of mice with gene manipulation. Micro-CT can quantify osteogenesis in mouse Ilizarov leg-lengthening procedures, osteoconduction in rat cranial defect models, and structural changes in arthritic rabbits, rats, and mice. Micro-CT can reproducibly quantify D microarchitecture of new bone formation inside the pores of titanium prosthesis implants is rabbits. In clinical studies, we evaluated longitudinal changes in iliac crests in premenopausal and postmenopausal women. Paired bone biopsies from postmenopausal women with osteoporotic fracture shows that D trabecular microstructure deteriorates in the iliac crest of postmenopausal osteoporotic women without active treatment. Three-dimensional microstructural parameters can predict fracture. Treatment of PTH in postmenopausal women with osteoporosis significantly improved trabecular morphology with a shift toward a more plate-like structure, increased trabecular connectivity, and increased cortical thickness. Paired bone biopsy specimens from the iliac crest in postmenopausal women with osteoporosis before and after beginning estrogen replacement therapy demonstrated in post-treatment biopsies a significant change in the ratio of plates to rods. High-resolution MR and μMR have received considerable attention both as research tools and potential clinical tools for assessment of osteoporosis. It has been used in studying human specimens or animal models of osteoporosis with various treatment strategies.MR microscopy has been shown to capable of differentiating trabecular structure in the distal radius and the calcaneus in postmenopausal women with or without os- teoporotic fracture. It has been used in studying human specimens or animals models of osteoporosis with various treatment strategies. A high field MR study show that ovariectomy in ewes induces deterioration of trabecular microstructure and biomechanical property of the femoral neck. These changes are prevented by calcitonin in a dose-dependent manner. Univariate analysis and multivariate stepwise regression analysis indicate that microarchitecture of trabecular bone contributes significantly to its biomechanical characteristics, independent of BMD measured in the femoral neck. Combination of trabecular microstructure with BMD improves prediction of bone quality.

LOTUS-inVivo Micro Computed Tomography System for Imaging of Small Animals and Ex-Vivo Biological Samples

“…Micro Computed Tomography (micro-CT) basically works the same as clinical CT and is a reliable imaging tool which provides volumetric information representing the inner structure of objects with a resolution in the micron range. Micro-CT has been an area of active research in biological, biomedical and even industrial imaging, with considerable utility and potential for pre-clinical and clinical applications [1][2][3].…”

The impact of spectral filtration on image quality in micro‐CT system

“…As a scaled‐down computed tomography (CT) imaging modality, micro‐CT was initially developed for industrial imaging applications and then for small animal imaging, but it recently has proven to be a useful tool in various clinical medical applications such as the assessments of the three‐dimensional (3D) bone microstructure and bone mineral density (BMD) performed on human legs or on bone biopsy specimens, the study of microvasculature anatomy, and the imaging of tumor perfusion and angiogenesis (1) . Micro‐CT is capable of providing 3D imaging at high resolution on the order up to 10 μm, enhancing the way of noninvasively and precisely visualizing the microarchitecture inside the object (2‐7) …”