A track-based scanning system uses an ultrasound probe that is mechanically guided through incremental scans over an area of interest. The scanning system can be configured for different patient applications using interchangeable track stands. Two-dimensional scan data and probe position information are fed back to a base unit for processing and assembly of a three-dimensional (3D) shape model. 3D abdominal aorta segmentation and other type of analysis may be performed based on a 3D vascular shape model and an intensity model.