Purpose: The use of intraoperative 5-aminolevulinic acid fluorescence has been shown to increase
the extent of resection in high-grade glioma surgery. Sodium fluorescein is an alternate
fluorescence agent with advantages of low cost, low adverse effect profile, and ability
to visualize anatomical detail under the fluorescence filter. Sodium fluorescein-based
fluorescence is not specific to tumor cells, and the significance of residual fluorescence
at tumor margins has been questioned. In this article, the authors sought to correlate
fluorescence intensity at tumor margins with the presence of residual contrast-enhancing
tumor on magnetic resonance imaging (MRI). Methods: Eleven patients with a total of 12 lesions were enrolled in the study. Sodium fluorescein
was administered at a dose of 5 mg/kg on induction of anesthesia. Relative intensity
of fluorescence was extrapolated from intraoperative photographs through isolation
of the green channel from the red/green/blue image, then graphically representing
of pixel intensity through application of a thermal map. The correlation between areas
of avid fluorescence at tumor cavity margins and the presence of residual contrast-enhancing
tumor on postoperative MRI was evaluated. Results: All tumors demonstrated fluorescence. The presence of avid fluorescence at tumor
cavity margins had a sensitivity of 66.7% and specificity of 75% for the presence
of residual contrast-enhancing tumor on postoperative MRI. There were no adverse effects
of fluorescein administration. Conclusion: Quantification of relative fluorescence intensity allows easy identification of areas
that are high risk for residual contrast-enhancing tumor. Graphical representation
of green pixel intensity requires validation through histopathological analysis but
has the potential for real-time clinical application.
Key-words:
Fluorescence brain tumor - fluorescence-guided surgery - high-grade glioma - sodium
fluorescein
