Surgical microscope with integrated fluorescence lifetime imaging for 5-aminolevulinic acid fluorescence-guided neurosurgery

J Biomed Opt. 2020 Feb;25(7):1-7. doi: 10.1117/1.JBO.25.7.071202.

Abstract

Significance: 5-Aminolevulinic acid (5-ALA)-based fluorescence guidance in conventional neurosurgical microscopes is limited to strongly fluorescent tumor tissue. Therefore, more sensitive, intrasurgical 5-ALA fluorescence visualization is needed.

Aim: Macroscopic fluorescence lifetime imaging (FLIM) was performed ex vivo on 5-ALA-labeled human glioma tissue through a surgical microscope to evaluate its feasibility and to compare it to fluorescence intensity imaging.

Approach: Frequency-domain FLIM was integrated into a surgical microscope, which enabled parallel wide-field white-light and fluorescence imaging. We first characterized our system and performed imaging of two samples of suspected low-grade glioma, which were compared to histopathology.

Results: Our imaging system enabled macroscopic FLIM of a 6.5 × 6.5 mm2 field of view at spatial resolutions <20 μm. A frame of 512 × 512 pixels with a lifetime accuracy <1 ns was obtained in 65 s. Compared to conventional fluorescence imaging, FLIM considerably highlighted areas with weak 5-ALA fluorescence, which was in good agreement with histopathology.

Conclusions: Integration of macroscopic FLIM into a surgical microscope is feasible and a promising method for improved tumor delineation.

Keywords: fluorescence lifetime imaging; fluorescence-guided neurosurgery; protoporphyrin IX; surgical microscope.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminolevulinic Acid
  • Brain Neoplasms* / diagnostic imaging
  • Brain Neoplasms* / surgery
  • Fluorescence
  • Humans
  • Neurosurgery*
  • Optical Imaging
  • Photosensitizing Agents
  • Protoporphyrins

Substances

  • Photosensitizing Agents
  • Protoporphyrins
  • Aminolevulinic Acid