Computer aided lytic bone metastasis detection using regular CT images

This paper presents a computer aided detection system to find lytic bone metastases in the spine. The CAD system is designed to run on routine chest and/or abdominal CT exams (5mm slice thickness) obtained during a patient's evaluation for other indications. The system can therefore serve as a background procedure to detect bone metastases. The spine is first automatically extracted based on adaptive thresholding, morphological operation, and region growing. The spinal cord is then traced from thoracic spine to lumbar spine using a dynamic graph search to set up a local spine coordinate system. A watershed algorithm is then applied to detect potential lytic bone lesions. A set of 26 quantitative features (density, shape and location) are computed for each detection. After a filter on the features, Support Vector Machines (SVM) are used as classifiers to determine if a detection is a true lesion. The SVM was trained using ground truth segmentation manually defined by experts.