gms | German Medical Science

Objective: Intraoperative MRI (iMRI) is increasingly used for resection guidance in glioma surgery to increase the extent of resection (EOR). For reasons of time- and cost efficacy however, iMRI is often applied in selected cases only which has limited the identification of its general benefits to date. This series shares our experience with iMRI in routine use in glioma surgery.

Methods: All gliomas scheduled for a tumor resection were routinely treated with the adjunct of iMRI and multimodal neuronavigation at our center. Consecutive iMRI surgeries from 01/2011-11/2017 were assessed in a prospective registry including patient age, tumor location, patient positioning, histologic diagnosis and the rate of additional resections after iMRI (AR). Volumetric analysis of pre-, intra- and postoperative MRI was completed in 2011-2013 (n=399). Descriptive statistics were applied for the analysis of intergroup variances to identify benefits of iMRI guidance.

Results: A total of 1048 iMRI guided tumor resections were performed. Mean patient age was 49±19years. Histology included WHO grades I-IV with a focus on malignant gliomas (WHO I: 73, WHO II: 154, WHO III: 186, WHO IV: 589, WHO undefined: 46). Tumors were evenly distributed in both hemispheres with a preponderance for frontal tumors (351 cases, 34%) and a minority of infratentorial tumors (46 cases, 4%). 29% of tumors (n=302) were recurrent lesions. AR was performed in 70% of cases (n=738). All surgeons had comparable rates of AR varying from 62-79% (p=0.17). Positioning was supine (881, 84%) or prone (167, 16%) which did not affect rates of AR (p=0.50). Volumetric analysis showed a mean increase of EOR of 11±19% after AR. Compared to WHO IV, WHO II tumors had significantly higher rates of AR (72% vs. 84%, p<0.01) and a higher mean residual tumor on iMRI (2.8±5.4ml vs. 3.8±4.1ml, p<0.05). Compared to primary resections, recurrent tumors had comparable rates of AR (72% vs. 68%, p<0.35) but exhibited a trend towards higher mean residual tumor on iMRI (2.5±3.9ml vs. 3.9±7.4ml, p=0.07).

Conclusion: This series shares our experience with iMRI in routine use in over 1000 cases. IMRI proved to be a reliable tool for resection guidance in glioma surgery facilitating the approach towards a maximized EOR. IMRI was of value in all WHO grades, in primary or recurrent lesions and provided a mutual benefit for surgeons of various experience levels. The ability of iMRI to increase EOR has to be evaluated against other guidance tools in the future.