Excision to the maximum possible extent marks the first step of glioma surgery. Depending on tumour histology, adjuvant treatment consists of radio- and/or chemotherapy. Multi-centre studies have shown that the presence of residual tumour according to MRI-criteria is a prognostic factor in this incurable condition.

In order to improve the extent of resection, several methods, in particular intraoperative imaging techniques, have become available to demonstrate already during surgery whether the goal of surgery has been achieved. The intraoperative MRI devices currently available differ in their magnetic field strengths and image resolution, but also in their amount of interference with the surgical workflow.

Prospective, high-class evidence data to promote the use of intraoperative MRI in glioma surgery are lacking. To assess whether the rate of radiologically complete tumour resections can be improved by using intraoperative MRI-guidance, we designed this prospective, randomized trial. We hypothesized that the extent of resection that can be achieved using an intraoperative MRI is greater than that of conventional microsurgical tumor resection.

Inclusion Criteria:

• known or suspected contrast-enhancing glioma (primary and recurrent)
• location of the tumor permits intended gross-total resection

Exclusion Criteria:

• tumor location prohibits or questions gross-total resection
• contraindications to undergo MRI examinations