Automated definition and evaluation of anatomical ROI's for bone mineral determination by QCT

The authors discuss reproducibility in determination of vertebral bone mineral density with quantitative X-ray computed tomography (QCT), which is significantly influenced by the operator's subjective selection of the region of interest (ROI). A method for automated ROI definition and evaluation based on contour detection and an anatomical coordinate system is presented and discussed. The method works reliably, offers improved reproducibility, and facilitates the operator's work. It is integrated into a program system that also supports automatic evaluation of different reference phantoms. The system has been used to create a large database of normal patients and is in clinical use at more than 100 sites.