Intraoperative ultrasound detection of metastatic tumors in the central cortex.

Real-time sector ultrasonography precisely located metastatic tumors of the central motor cortex during craniotomy in two patients. In these two cases, the only surface abnormality was swelling of several overlying gyri. Intraoperative ultrasonography precisely located the 1.5- and 2.5-cm-diameter tumors to a position below a specific gyrus, enabling the surgeon to excise the tumors through small, accurately placed cortical windows. The precise location minimized exploratory probing and the size of the cortical incision required to identify and remove the tumors. This technique will have general application in similar situations when the cortical surface gives no indication of underlying tumor location. By charting the best trajectory for the surgical approach, this technique may replace a variety of stereotactic and computed tomography-guided techniques for biopsy of deep brain tumors.