Subjects, Materials, and Methods

Sonography was used to detect and localize intracranial lesions intraoperatively in 16 patients and to examine 31 patients (47 exams) postoperatively for a variety of clinical problems. Current sonographic technology was effective for localizing and differentiat-ing cystic and solid intracranial pathology and for determining the size and boundaries of the intracranial lesions and their distance from the cortical surface. It was used occasionally as an aid for circumventing intracranial vessels during tissue dissection and, when used, determined the completeness of tumor dissection. Sonography also proved to be a reliable postoperative tool when surgically created cranial windows were present, but the location and size of the surgical window were critical to the quality of the images obtained. Both applications of this technique complement computed tomog-raphy and therefore can serve as a valuable adjunct in the treatment and follow-up of the neurosurgical patient. Intraoperative sonography of the brain has been shown to have applications in neurosurgery [1-14]. Previously, we reported the intraoperative scanning of eight patients, in which a bulky linear-array ultrasonic transducer and an ATL (Advanced Technology Labs., Bellevue, WA) Mark III limited to 3 and 5 MHz frequencies were used [11]. We now report intraoperative and postoperative scanning with a later model, the ATL Neuro-SectOR, which can be set to deliver one of three different frequencies, including 7.5 MHz, from the same transducer head (725B)