Design of the image-guided biopsy marking system for gastroscopy.

Endoscopists currently rely on an invasive biopsy tattooing method to identify previously biopsied sites. In order to better guide endoscopists to find the biopsy positions in follow-ups, we proposed a non-invasive image guided biopsy marking system for gastroscopy. Using an electromagnetic tracking device, the position of the gastroscope relative to the stomach was acquired and displayed in the guidance interface. The biopsy positions were recorded in computer for the use of guidance in follow-ups. The accuracy of the system was evaluated by both phantom experiments and in vivo experiments. The average target registration errors on the test animal and the volunteer are 13.4 mm and 11.2 mm respectively. Although the positioning error is slightly larger than current biopsy tattooing method, it satisfies the need for guidance. In the near future, we will validate the system by measuring how much it saves examination time.