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Published on: August 6, 2019
Intraoperative MRI and FLAIR Analysis: Implications for low-grade glioma surgery
Myriam Edjlali1, Loïc Ploton2, Claude-Alain Maurage3
1IMABRAIN, Inserm-UMR1266, Department of Neuroradiology, université Paris-Descartes-Sorbonne-Paris-Cité, DHU Neurovasc, centre hospitalier Sainte-Anne, Paris, France; Department of Neuroradiology, CHU Lille, 59000 Lille, France.
Purpose:
Intraoperative MRI (iMRI) offers the possibility of acquiring intraoperatively real-time images that will guide neurosurgeons when removing brain tumors. The objective of this study was to report the existence of FLAIR abnormalities on iMRI that may occur on the margin of a brain resection and may lead to misdiagnosis of residual tumor.
Methods:
We retrospectively analyzed intraoperative MRI (iMRI) in 21 consecutive patients who underwent surgery for a low-grade glioma. Two readers independently reviewed iMRI images to search for the presence of a FLAIR hyperintensity surrounding the surgical cavity. For each patient, they were instructed to characterize FLAIR abnormalities on the margins of the resected area as (1) no FLAIR abnormality; (2) "linear FLAIR hyperintensity (LFH)", when a<5mm linear FLAIR hyperintensity was present; or (3) "nodular FLAIR hyperintensity (NFH)", in the case of a thick and nodular FLAIR hyperintensity.
Results:
LFH were present on at least one surgical margin of one third of the patients analyzed with iMRI, and vanished on follow-up MRI, confirming its transient condition; whereas NFH were linked to persistence of pre-surgical abnormalities, such as residual tumor as confirmed or by histopathological analysis of a second surgery or by its remnant on follow-up MRI.
Conclusion:
Linear FLAIR hyperintensities can be present on surgical margins analyzed by iMRI and should not be mistaken for residual tumor.
Insights
Intraoperative MRI (iMRI) can show linear FLAIR hyperintensities at tumor resection margins. These transient findings on iMRI should not be misdiagnosed as residual low-grade glioma tumor.
Area of Science:
- Neurosurgery
- Neuroradiology
- Oncology
Background:
- Intraoperative MRI (iMRI) provides real-time imaging during brain tumor removal.
- Accurate assessment of resection margins is crucial for optimal patient outcomes.
Purpose of the Study:
- To identify and characterize FLAIR abnormalities at resection margins visualized by iMRI.
- To determine if these abnormalities represent residual tumor or transient changes.
Main Methods:
- Retrospective analysis of iMRI scans from 21 patients with low-grade gliomas.
- Independent review of iMRI images by two readers to detect FLAIR hyperintensities.
- Classification of FLAIR abnormalities as linear (LFH) or nodular (NFH).
Main Results:
- Linear FLAIR hyperintensities (LFH) were observed in one-third of patients at surgical margins.
- LFH resolved on follow-up MRI, indicating a transient phenomenon.
- Nodular FLAIR hyperintensities (NFH) correlated with residual tumor confirmed by follow-up or histopathology.
Conclusions:
- Linear FLAIR hyperintensities on iMRI at resection margins are common.
- These linear findings should not be misinterpreted as residual tumor.
- Distinguishing LFH from NFH is critical for accurate intraoperative assessment.
