Intraoperative neurosurgical ultrasound in the localization and characterization of intracranial masses.

Seventy-two lesions were demonstrated in 70 patients who were examined using intraoperative real-time ultrasonography. Fifty-five lesions were supratentorial and 17 were infratentorial. The neurosurgeon used ultrasonography to evaluate his operative field before, during, and after resection. Nineteen lesions contained cystic components. In eight cases, ultrasonography added information not provided by CT including definitive characterization of cystic components and loculations or localization of solid masses within the cysts. Biopsy of 13 lesions was performed under ultrasonic guidance. In all cases, the biopsy probe could be seen passing through the lesions leaving an echogenic trail, possibly blood filled, after the probe had been removed. Three lesions with diameters of less than 1 cm were localized and successfully removed under ultrasonic guidance. Intraoperative real-time ultrasonography is a safe and reliable technique, and it can be a valuable aid to the neurosurgeon.