Improving the Usability of 5-Aminolevulinic Acid Fluorescence-Guided Surgery by Adding an Optimized Secondary Light Source

Abstract

Tumors that take up and metabolize 5-aminolevulinic acid emit bright pink fluorescence when illuminated with blue light, aiding surgeons in identifying the margin of resection. The adoption of this method is hindered by the blue light illumination, which is too dim to safely operate under and therefore necessitates switching back and forth from white-light mode. The aim of this study was to examine the addition of an optimized secondary illuminant adapter to improve usability of blue-light mode without degrading tumor contrast. Color science methods were used to evaluate the color of the secondary illuminant and its impact on color rendering index as well as the tumor-to-background color contrast in data collected from 7 patients with high-grade gliomas (World Health Organization grade III and IV). A secondary illuminant adapter was built to provide 475-600 nm light the intensity of which can be controlled by the surgeon and was evaluated in 2 additional patients. Secondary illuminant color had opposing effects on color rendering index and tumor-to-background color contrast; providing surgeon control of intensity allows this trade-off to be balanced in real time. Demonstration in 2 high-grade glioma cases confirms this, showing that additional visibility adds value when intensity can be controlled by the surgeon. Addition of a secondary illuminant may mitigate surgeon complaints that the operative field is too dark under the blue light illumination required for 5-aminolevulinic acid fluorescence guidance by providing improved color rendering index without completely sacrificing tumor-to-background color contrast.