For the intraoperative ultrasound monitoring, we have investigated to minimize the size of a sector type probe and have clinically applied it in several neurosurgical procedures, particularly in cases of deep-seated-brain tumors. The ultrasound monitoringwith our newly developed sector probe can provide many useful informations in real time during the operation for deep-seated lesions. The sector probe is 14mm in outer diameter and is working in 5 MHz. Combined use of the ISEKI-stereotactic apparatus and the ultrasonography with this sector probe provided beneficial informations for stereotactic biopsy or deep brain surgery, since it has the potential to identify anatomical localization of a tumor or other lesions at any time during surgical manipulations. We have also developed a rotating ultrasound probe turning around by a computer-controled stepping motor. By using this rotating ultrasound probe, it was possible to visualize intracerebral lesions tangentially and it's surrounding anatomical structures in round-shaped area, approximately 2 cm in diameter along one trajectory of the probe. Our newly developed intraoperative monitoring system is an useful tool for stereotactic biopsy or neurosurgery of deep-seated brain tumors or other lesions.
