"Osteoporosis is defined as a state of low bone density with underlying alterations in bone microarchitecture leading to an increased fracture risk. The incidence of osteoporosis is rising globally and produces increasing costs to national health care systems since osteoporotic patients are prone to low trauma fractures. Osteoporotic fractures are not only a matter of decreased bone density, but are also associated with alterations in the microarchitecture of the trabecular structure within the bone due to dynamic processes of bone rebuilding and resorption. In clinical practice, histomorphometric analysis of iliac crest biopsies is the current method of reference in the assessment of bone microarchitecture. Bone biopsy, however, is an invasive procedure which allows a limited number of follow-ups while providing limited information about the larger scale bone micro-architecture. Micro computed tomography (microCT) and very recently High-resolution peripheral quantitative computed tomography (HR-pQCT) have enriched bone research by enabling a three-dimensional approach to bone imaging. A particular feature of HR-pQCT is the possibility to acquire high resolution in vivo images, thereby allowing for follow-up observations. At present, however, the resolution of HR-pQCT does not allow for direct inference of the cellular and re-modeling processes within the bone. The goal of this project is to bridge the gap between bone microarchitecture and local re-modeling processes of bone resorption and rebuilding by developing methods for detection of osteoclastic sites and eroded trabecular surfaces in microCT, and ultimately HR-pQCT images through multi-modal analysis using to bone histology images. Such detection will have a clinical impact by improving the ability to target therapy and drugs based on the underlying nature of the disease. In addition, localization of these sites could be used to improve biological bone models at the cellular, tissue, and structural levels."