Maximizing the extent of resection and survival benefit of patients in glioblastoma surgery: High-field iMRI versus conventional and 5-ALA-assisted surgery
Introduction
Intraoperative magnetic resonance imaging (iMRI) has been used for more than a decade aiming to achieve better results in the resection of gliomas. Literature shows that the extent of resection (EOR) of contrast enhancing lesions might be improved by iMRI.1, 2, 3, 4, 5, 6, 7, 8, 9, 10 A radical and safe tumor removal appears to be one of the most important prognostic factors in patients with glioblastomas (GBM).8, 11, 12, 13, 14, 15 Recent literature shows a benefit concerning the EOR in around 30–40% of all cases comparing the intraoperative and the postoperative MR scans.6, 7, 13, 16, 17, 18 While there are few studies comparing the intraoperative versus the postoperative residual tumor-volume, scarce evidence is available on the advantage of iMRI-guided versus conventional glioma resection.8, 9, 19 Only three studies (two retrospective and one prospective randomized) comparing iMRI-guided and conventional resection were published to date showing a benefit for the iMRI-group in terms of the EOR and survival.8, 19, 20 As of today's knowledge on state-of-the-art resection techniques for high-grade gliomas, 5-ALA fluorescence-guided resection appears to be the most radical method in terms of the EOR in conventional surgery. Due to the high expenses associated with iMRI (especially the high-field one) and the desire for continuous improvement of patient treatment and survival, there is a strong need to evaluate the use of iMRI-assisted surgery in comparison to cheaper and established supportive resection techniques such as 5-ALA. Therefore, we analyzed the EOR along with clinical, surgery-related chronological and 6M-PFS data comparing high-field iMRI-guided versus conventional surgery with and without 5-ALA in the resection of glioblastomas.
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Patient cohort
This was a single-institution protocol driven, retrospective study approved by the local institutional review board. All patients provided informed consent for the analysis of clinical data. We reviewed the records of consecutive patients from the clinical database, who underwent resection of glioblastomas between June 2010 and November 2012. IMRI-guided surgery was available since July 2011. Eligibility criteria were as follows: histopathologically verified glioblastoma multiforme (WHO grade
Results
Medical records of patients who underwent resection of glioblastoma multiforme were analyzed to evaluate the extent of resection, clinical parameters and 6M-PFS of iMRI-, 5-ALA- and conventional white-light-guided surgery. Inclusion criteria were met in 117 patients, 57 before and 60 after the iMRI unit was opened. MRI was not available or of insufficient quality for volumetry due to movement artifacts in 15% of the preoperative and 8% of the postoperative cases. 7% of the patients were lost
Discussion
The complete resection of glioblastomas with preservation of neurological function should be the primary therapeutic goal before starting adjuvant therapies to achieve the longest survival with good life quality possible to date.14, 15 To achieve this goal, 5-ALA and intraoperative MRI are the cutting-edge supportive techniques at this time.8, 9, 21 While 5-ALA provides the possibility to identify fluorescent tumor tissue in the resection cavity through the microscope in a real-time manner,
Conclusion
The present study is the first to provide evidence of the additional value of high-field iMRI in terms of extent of resection, perioperative clinical data and 6M-PFS compared to state-of-the-art conventional glioblastoma surgery with and without 5-ALA. Our analysis demonstrated that iMRI may be significantly superior to conventional surgery (with and without 5-ALA) for extended tumor resection and thus, higher number of total resections with comparable peri- and postoperative morbidities. The
Conflicts of interest
CR, SB and MT have received honoraria as speakers from IMRIS GmbH, Nürnberg, Germany. None of the other authors have any potential conflicts of interests to disclose.
Funding
None.
Acknowledgments
We thank the anesthesiologists and OR staff who support surgeries at the iMRI unit.
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Authors contributed equally.