Automatic video tagging method for cortical mapping in awake craniotomy records

Operation video recording is one of efficient methods for analyzing surgical workflow and intraoperative incident detection. In "Intelligent Operating Room" at Tokyo Women's Medical University Hospital, the special neurological surgery called awake craniotomy is recorded by video recording system IEMAS (Intraoperative Examination Monitor for Awake Surgery). There are a number of useful video records of surgical procedure such as patient reactions and surgical operations. However, these surgical event tags which are used for surgcial workflow analysis are not contained in IEMAS records. IEMAS is composed multi-view video cameras, so manual tagging for video records is a lot of labor because of the large length of surgical operation videos. In awake craniotomy, electrical stimulation is one of significant surgical operations for detecting eloquent brain areas. In this paper, we propose the automatic detection method for the stimulation points onto patient's brain areas from raw IEMAS video records by using image processing approach. In the previous work, we proposed stimulation timing detection method from surgery sound records of IEMAS. Hence, we propose a detection method of surgical instrument for electrical stimulation in order to tag the stimulated positions on surgical view. However, detected positions on the video frame coordinates depend on camera view changes. Therefore, we map video frame positions to representative video frame positions by using homography transformation in order to enable to analyze stimulated points relation. We applied automatic video tagging method for several raw IEMAS video records and show its performance.