Endoscopic ultrasound imaging with high flow mode for endonasal transsphenoidal pituitary surgery.

Intraoperative ultrasound during transsphenoidal surgery (TSS) for pituitary tumors has been reported. In reports of endonasal ultrasound (US), Doppler US vessel images were informative and effective in endoscopic TSS. We performed endoscopic US imaging with high flow mode, which is a novel technology, to visualize small vessels during endonasal endoscopic TSS. Six patients (five with pituitary adenomas and one with Rathoke's cleft cyst) underwent endoscopic US-assisted TSS. A small endoscopic US probe (Olympus, BF-UC260FW; diameter, 6.9 mm) was inserted transsphenoidally to the sellar floor and into the sella turcica, and endoscopic US monitoring was performed. By rotating the endoscopic US probe, the internal carotid artery, anterior cerebral artery, middle cerebral artery, various small vessels, optic nerve, and residual tumor were clearly visualized on the endoscopic US images. Real-time animated vessel images around the tumor could be generated when needed during TSS. The tumors were removed without leakage of cerebrospinal fluid in the six patients, and their visual acuity was restored. Endoscopic US with high flow mode can visualize not only main cerebral arteries but also intracranial small vessels on B-mode US images. Pituitary tumors were clearly recognized and removed safely and precisely by monitoring the cerebral artery and its small branches as landmarks.