Multimodal optical analysis discriminates freshly extracted human sample of gliomas, metastases and meningiomas from their appropriate controls

Abstract

Delineating tumor margins as accurately as possible is of primordial importance in surgical oncology: extent of resection is associated with survival but respect of healthy surrounding tissue is necessary for preserved quality of life. The real-time analysis of the endogeneous fluorescence signal of brain tissues is a promising tool for defining margins of brain tumors. The present study aims to demonstrate the feasibility of multimodal optical analysis to discriminate fresh samples of gliomas, metastases and meningiomas from their appropriate controls. Tumor samples were studied on an optical fibered endoscope using spectral and fluorescence lifetime analysis and then on a multimodal set-up for acquiring spectral, one and two-photon fluorescence images, second harmonic generation signals and two-photon fluorescence lifetime datasets. The obtained data allowed us to differentiate healthy samples from tumor samples. These results confirmed the possible clinical relevance of this real-time multimodal optical analysis. This technique can be easily applied to neurosurgical procedures for a better delineation of surgical margins.

Figure 1. Results of spectroscopic endogenous fluorescence measurements for intra-axial tumor part.

Fluorescence intensity of NADH and FAD when exciting with 405 and 375 nm for Glioma, metastasis and control samples. Results for Lipopigment, porphyrin I and II are presented for 405 nm excitation wavelength. ^★★Under a bar denote statistically significant difference (p < 0.01).

Figure 2. Results of spectroscopic endogenous fluorescence measurements for extra-axial tumor part.

Fluorescence lifetime of NADH and FAD when exciting with 405 and 375 nm from meningioma and control samples. Results for Lipopigment, porphyrin I and II are presented for 405 nm excitation wavelength.

Figure 3. Box plot of endogenous fluorescence lifetime measurements for intra-axial tumor part.

Lifetime variation of NADH and FAD when exciting with 405 and 375 nm from Glioma, metastasis and control samples. Results for Lipopigment, porphyrin I and II are presented for 405 nm excitation wavelength. * and ** denote statistically significant difference (p < 0.05 and p < 0.01, respectively).

Figure 4. Box plot of Endogenous Fluorescence lifetime measurements for extra-axial tumor part.

Lifetime variation of NADH and FAD when exciting with 405 and 375 nm from tumorous and control tissue. Results for Lipopigment, porphyrin I and II are presented for 405 nm excitation wavelength. * and ** denote statistically significant difference (p < 0.05 and p < 0.01, respectively).

Figure 5

Multimodal analysis of intra and extra- axial tumor analysis of glioma (A) and metastasis (B) samples versus control samples (C) and meningioma control sample (D). From top to bottom: Axial MR slice on contrast enhanced T1-weighted sequence. Spectra at 890 nm excitation wavelength from nonlinear set-up showing a clear peak of SHG at 445 nm. Image from nonlinear set-up showing SHG signal in green and fluorescence in red. Hematoxylin-Eosin staining Images. Scale bars: 100 μm. Spectra analysis: X-axis: emission wavelength (nm) and Y-axis: Fluorescence intensity (a.u.); Fitted by Matlab software: blue, purple and green line represent respectively NADH, FAD and lipopigment fluorescence emission spectra. Red and purple dot lines for porphyrin I and porphyrin II.

Figure 6. Optical fibered endoscope set up.

Spectral and lifetime measurements were acquired using this set up and under 405 and 375 nm excitation wavelength. Two fibered was used for excitation and fluorescence collection.