Introduction: 5-ALA fluorescence guided surgery significantly contributed to increase the extent of resection (EOR) of high grade gliomas,allowing the detection of pathological tissue also in the areas surrounding the tumoral contrast-enhanced nodule. EOR measurement is based on comparison between pre- and post-operative volumetric evaluation of contrast enhanced tumor in T1 with gadolinium Magnetic Resonance (MR) sequences. This study tests the efficacy and reliability of EOR evaluation of high grade gliomas based on 3D FLAIR MR images used for intra-operative navigation and post-operative measurement.
Methods: 16 patients have been prospectically included. All patients underwent a pre-operative MR protocol study including spectroscopy, 3D contrast-enhanced T1, 3D FLAIR and Diffusion Tensor Imaging (DTI). Both 3D post-contrast T1 and FLAIR sequences have been used for intra-operative navigation. The correspondence between intensity of fluorescence and MR images has been evaluated by neuronavigation. Volumetric evaluation of extent of resection has been performed using manual segmentation on 3D FLAIR sequences of pre- and post-operative MR.The same evaluation has been performed on other 25 patients retrospectively evaluated.
Results: Correlation between 3D FLAIR, 3D T1 post-contrast images and intraoperative 5-ALA fluoresccence revealed the correspondence between enhanced tumor and intense fluorescent areas in all cases.Peri-tumoral zones, detectable on 3D FLAIR sequences as hyperintense, appeared with vague fluorescence and have been istologically demonstrated as pathological infiltrating areas in 12 of 16 patients.Volumetric evaluation based on 3D-FLAIR MR has been performed on 41 patients.In 21 patients, residual tumor has been detected,despite traditional volumetric evaluation based on T1 post-contrast MR showed complete resection in all cases.Only three of these 21 patients were included in the prospective group.
Conclusions: Resection based on 3D FLAIR images is wider than that based on post-contrast T1.The safety of such resection depends on the use of navigated tractography and neuromonitoring.The validity of the method proposed must be supported by survival data.
Patient Care: The proposed methods should allow a more extended, but still safe resection of gliomas.
Learning Objectives: By the conclusion of this session, participants should be able to:
- Describe the importance of extended resection in brain tumor surgery
- Point out the correlation between pre-operative imaging and intraoperative findings in glioma surgery
- Discuss the pros- and cons- of 3D FLAIR based neuronavigation during high-grade glioma resection