Magnetic source imaging in stereotactic and functional neurosurgery

Magnetic source imaging (MSI) combines the unique spatial and temporal functional accuracy of magnetoencephalography (MEG) with the anatomic and pathologic detail of magnetic resonance (MR). This relatively new method of evaluating brain function provides a preoperative mapping of brain function and brain structure by integrating the functional information of MEG with the structural information of MR. This results in data on actual neuronal interactions in clinical patients. The temporal and spatial accuracy of the MEG data, combined with the anatomic and pathologic specificity of MRI, results in the magnetic source image, which offers accurate knowledge of cortical functional organization, and is important in the surgical treatment of brain neoplasms, vascular malformations, and epilepsy. MSI allows the tracking of neuronal activity on the scale of milliseconds with millimeter accuracy, and continues to lead to new understanding of many functional brain disorders.