X-ray guided three-dimensional diffuse optical tomography: In vivo study of osteoarthritis in the finger joints

Osteoarthritis (OA), characterized by the damage of the articular cartilage, is the most common joint problem worldwide. In the effort of developing new clinical tools with the potential to alter the natural history of OA, near-infrared diffuse optical tomography (DOT) has received much attention due to its unique advantages. For optical imaging in highly heterogeneous media such as the finger joints, prior information could improve the quality of optical imaging. We report a hybrid imaging system for early detection of OA in the finger joints by imposing the geometry information obtained by X-ray on three-dimensional near-infrared DOT. X-ray tomosynthesis was employed to recover the three-dimensional structure of the two bones based on 16 X-ray projections generated with a mini C-arm system at different directions within a range of 180 degrees. The interface was carefully designed to guarantee an accurate co-registration of the optical and x-ray modalities. The prior structural information of bones was incorporated into our multi-modality imaging reconstruction algorithm to enhance the recovery of the optical properties of joint tissues. Several healthy and OA finger joints were examined. The initial clinical results showed that this hybrid imaging system had the ability to provide much enhanced image resolution and contrast than DOT alone for OA detection.