Intraoperative sonographic delineation of low-grade brain neoplasms defined poorly by computed tomography

Sixty-four consecutive primary or metastatic brain tumors were reviewed to assess the efficacy of intraoperative sonography for localization, biopsy, and/or drainage. In 12 cases, preoperative CT data were incomplete or confusing, usually due to low-density, non-enhanced areas in which low-grade tumor could not be reliably differentiated from necrosis, edema, or cyst. In each case, intraoperative sonography clarified the nature of the solid tumor component by its distinct hyperechogenicity, facilitating biopsy. As a guide to surgical biopsy of brain tumors, sonography has some advantages even over stereotactic systems, which depend upon accurate CT definition of the lesion.