Introduction: Surgical treatment of glioblastoma remains challenging. New imaging modalities including 5-aminolevulinic (5-ALA) fluorescence and intra-operative MRI (iMRI) may improve surgical resection and prolong survival. We evaluated 5-ALA fluorescence versus low field iMRI for resection control in glioblastoma surgery.
Methods: 14 patients with suspected glioblastoma received surgical treatment using 5-ALA induced fluorescence and frameless navigation. Following complete resection of 5-ALA fluorescent tissue, which was verified by two neurosurgeons, intra-operative low field MRI (Pole Star, Medtronic) was applied. If areas suspicious of tumor were identified they were biopsied under navigation guidance. Tissue samples were also taken from various 5-ALA enhancing locations before iMRI. All data were collected prospectively and the histological analysis was blinded.
Results: In 13 of 14 cases the diagnosis was glioblastona. One case was lymphoma and excluded from the study. 12 of 13 operations showed 5-ALA fluorescence, one case failed to show fluorescent tissue and was also excluded. In 11 of 12 operations residual contrast enhancement on iMRI was found after complete resection of 5-ALA fluorescent tissue. The histological assessment of 27 samples of the 11 cases which showed contrast enhancing residual tumour on iMRI showed tumour in 9 cases (33.3%), infiltration zone in 7 (25.9%), reactive CNS tissue in 10 (37%) and only 1 case (3.7%) without pathological changes.
Conclusions: Not all glioblastoma tissue shows 5-ALA fluorescence and not all i-MRI contrasting regions contain tumor. I-MRI performed after complete resection of 5-ALA fluorescent tissue shows contrast enhancing regions suspicious of remnant glioblastoma in a very high percentage of cases (92%) and tissue samples taken from these locations reveal tumor or tumor infiltration zone in the majority of cases (58%). This data reveals the sensitivity limitations of 5-ALA fluorescence. However, due to low specificity the extended resection of i-MRI contrast enhancing areas has to be considered with caution in eloquent areas.
Patient Care: It helps optimising glioblastoma resection
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe and discuss the diffences in intra-operative tumor identification with 5-ALA flourescence versus iMRI 2) discuss safety and efficacy in 5-ALA and iMRI guided glioblastoma resection.