Medical image retrieval and registration: towards computer assisted diagnostic approach

A large number of medical images in digital format are generated by hospitals and clinics every day. Such images constitute an important source of anatomical and functional information for diagnosis of diseases, medical research and education. These images include high-resolution 2-D or 3-D spatial and temporal data of various modalities (CT, MRI, X-ray, ultrasound etc.) require effective processing and organization techniques. Two of the most important techniques along this direction are; image retrieval and image registration. Image retrieval is the technique to find similar images from an image archive by their textual and visual contents and image registration is the establishment of correspondences between images or between image and physical space. Characteristics of medical images differ significantly from other general-purpose images and hence require special treatment. This article presents a highlight of recent research in medical image retrieval and registration, main techniques and trends, key issues and limitations. We also point out some promising research directions and propose a system architecture for computer aided diagnosis, where both technologies can be integrated and complement each other.