Three-dimensional (3D) ultrasound imaging of the gallbladder and dilated biliary tree: reconstruction from real-time B-scans

Abstract

Ultrasound is perhaps the most operator-dependent imaging technique. Clinicians rarely master the interpretation of ultrasound images and even experienced ultrasonographers may experience difficulty interpreting “hard copy” images produced by other operators. Reconstructed three-dimensional (3D) computer images of computed tomography (CT) scans have been shown to aid interpretation of CT data by clinicians, particularly before reconstructive and orthopaedic surgery (Lafferty et al, 1986; Linney et al, 1989). We propose that similar reconstruction of ultrasound images may aid clinicians' understanding of the anatomy of the enlarged biliary tree and gallbladder. Ultrasound studies of the biliary tree were performed using a Toshiba 100 real-time ultrasound system with a 3.5 MHz curved array transducer. The probe was located on the skin surface, then smoothly rotated by hand at the probe face so as to obtain a continuous, sequential sweep across the volume of the liver. The sequence of B-scans obtained was recorded on videotape. The angle of rotation of the probe was estimated by eye. Regular sample frames of the videotaped data were selected for digitization by frame by frame examination of the videotaped data. Images were digitized using an Oggitronics 8-bit recursive video processor. The images were transferred to a DEC VAX 11–730 minicomputer and SIGMEX A7000 display processor, running the Southampton General Hospital PICS general image processing software (Fleming et al, 1987). Images were compressed to 256 × 256 pixel square matrix format. In each study, 20–30 sample images were taken.