  In this paper we present a new 3D segmentation approach for the vertebrae of
the lower thoracic and the lumbar spine in spiral computed tomography datasets.
We implemented a multi-step procedure. Its main components are deformable
models, volume growing, and morphological operations. The performance analysis
that included an evaluation of accuracy using the European Spine Phantom, and
of intra-operator precision using clinical CT datasets from 10 patients
highlight the potential for clinical use. The intra-operator precision of the
segmentation procedure was better than 1% for Bone Mineral Density (BMD) and
better than 1.8% for volume. The long-term goal of this work is to enable
better fracture prediction and improved patient monitoring in the field of
osteoporosis. A true 3D segmentation also enables an accurate measurement of
geometrical parameters that can augment the classical measurement of BMD.
