INTRAOPERATIVE DIAGNOSTIC AND INTERVENTIONAL MAGNETIC-RESONANCE-IMAGING IN NEUROSURGERY

OBJECTIVE: The benefits of intraoperative magnetic resonance (MR) imag ing for diagnostic and therapeutic measures are as follows: 1) intraop erative update of data sets for navigational systems, 2) intraoperativ e resection control of brain tumors, and 3) frameless and frame-based on-line MR-guided interventions. The concept of an intraoperative MR s canner in the sterile environment of the operating theater is presente d, and its advantages, disadvantages, and limitations are discussed. M ETHODS: A 0.2-tesla magnet (Magnetom Open; Siemens AG, Erlangen, Germa ny) inside a radiofrequency cabin with a radiofrequency-shielded slidi ng door was installed adjacent to one of the operating theaters. A spe cially designed patient transport system carried the patient in a fixe d position on an air cushion to the scanner and back to the surgeon. R ESULTS: In a series of 27 patients, intraoperative resection control w as performed in 13 cases, with intraoperative reregistration in 4 case s. Biopsies, cyst aspirations, and catheter placements (mainly framele ss) were performed under direct MR visualization with fast image seque nces. The MR-compatible equipment and the patient transport system are safe and reliable. CONCLUSION: Intraoperative MR imaging is a safe an d successful tool for surgical resection control and is clearly superi or to computed tomography. Intraoperative acquisition of data sets eli minates the problem of brain shift in conventional navigational system s. Finally, on-line MR-guided interventional procedures can be perform ed easily with this setting. As with all MR systems, individual testin g with phantoms, application of correction programs, and determination of the optimal amount of contrast media are absolute prerequisites to guarantee patient safety and surgical success.