A mobile high-field magnetic resonance imaging system for neurosurgery

The use of intraoperative MRI for the treatment of glioblastoma multiforme

Outcome for patients with glioblastoma multiforme (GBM) is improved with aggressive surgical resection followed by standard chemotherapy and radiation therapy. Intraoperative MRI (iMRI) is a recent surgical advancement that gives neurosurgeons direct radiographic feedback throughout a surgical procedure and thus enables maximal surgical resection of such lesions. We reviewed our series of 35 cases in 29 patients who underwent surgical resections of their GBM's using iMRI. The average extent of resection was 94% with only three patients having resections of less than 90%. However, even with such technology complete resection may not always be possible because of tumor location near critical brain structure or involvement of surrounding vascular structures. The addition of iMRI to the surgical armamentarium for treatment of patients with GBM improves the degree of tumor resection while minimizing complications and thus may positively impact survival in this patient population.

Clinical evaluation and follow-up results for intraoperative magnetic resonance imaging in neurosurgery

OBJECTIVE

The use of intraoperative magnetic resonance imaging (MRI) in neurosurgery has increased rapidly, and a variety of concepts have recently been presented. Although the feasibility of the procedure has been demonstrated repeatedly, no conclusive analysis of its effects on the surgical procedures, the extent of tumor removal, and outcomes, or its possible problems, has been performed.

METHODS

Of 242 operations performed with intraoperative MRI, 97 procedures for supratentorial glioma treatment were analyzed with respect to intraoperative imaging results and postoperative outcomes. Analysis of the images included assessment of imaging artifacts, image quality, and extent of tumor removal. Patients were monitored to determine radiological progression, survival times, postoperative complications, and morbidity rates.

RESULTS

No intraoperative complications related to the imaging procedure were observed. Image quality was good or fair in 85.5% of the cases. Different types of surgically induced imaging changes could be identified. In 56 cases, resection was continued using navigation with intraoperative MRI data sets (rereferencing accuracy, 0.9 mm). For high-grade gliomas, the percentage of cases in which residual tumor was identified by MRI could be significantly reduced from 62% intraoperatively to 33% postoperatively, which was paralleled by a significant increase in survival times for patients without residual tumor. Complication and morbidity rates were within the ranges reported for other studies.

CONCLUSION

Intraoperative MRI is safe and allows reliable updating of neuronavigational data, with compensation for brain shifting. Surgically induced imaging changes, which have been identified as a possible problem with intraoperative MRI in general, necessitated comparisons with preoperative scans and require future attention. The extent of tumor removal and survival times were increased significantly. Overall, patients seemed to benefit from the method.

An integrated head-holder/coil for intraoperative MRI in open neurosurgery

With the invention of "open" magnetic resonance imaging (MRI) systems, access to the patient is possible during the imaging procedure. An important application of these systems is intraoperative MRI to control the extent of resection during tumor surgery. Up to now flexible surface coils wrapped around, or placed at each side of the head, were used for imaging. These flexible coils have several disadvantages such as unreliability, interindividual problems, difficult handling, poor hygienic properties, and often unsatisfactory or inhomogeneous image quality. To solve most of these problems, an MR-compatible head-holder in combination with an integrated surface coil for use in a 0.2 T C-shaped magnet was developed. Forty-eight patients with known cranial tumors underwent MRI intraoperatively. In 32 patients (67%), residual tumor was found, and additional surgical resection was performed. The integrated head-holder/coil is a safe and practical tool for intraoperative MRI, providing efficient and reliable resection control during neurosurgical procedures.