UCSF

Abstract Introduction: 5-aminolevulinic acid (5-ALA) fluorescence-guided surgery has become a valuable adjunct in the resection of malignant intracranial gliomas. Furthermore, the fluorescence intensity of biopsied areas of a resection cavity correlates with histological identification of tumor cells. However, in the case of lesions deep within a resection cavity, light penetration may be suboptimal, resulting in less excitation of 5-ALA metabolites leading to decreased fluorescence emission. Here, we demonstrate the use of a 400 nm fiber optic light source incorporated into a surgical suction instrument that simultaneously allows for removal of blood products and improvement of tumor fluorescence by providing necessary wavelength-specific illumination to deeper areas of a resection cavity. Materials and Methods: A SpetzlerTM Lighted Suction Tube (Kogent Surgical, Chesterfield, MO) was connected to a custom-designed 400 nm wavelength emitting light source built using a Luxtec model LX-300 fiber optic illuminator (Integra, Plainsboro, NJ) with a 400 nm filter (Product number #84-781, Edmund Optics, Barrington, NJ) installed in the optical path. The 400 nm lighted suction instrument was used during the resection of the tumor, both for removing blood products and tumor tissue as well as to illuminate areas of the deep resection cavity to probe for remaining areas of 5-ALA positivity. Results: We present the techniques described, including the intraoperative set-up and the equipment utilized. We also describe the use of this technique in several cases of malignant glioma resection. This technique improved the fluorescence intensity of patches of malignant tissue deep within the resection cavity. Light emanating from the instrument did not cause auto-fluorescence when no 5-ALA positive tissue was present. Furthermore, no evidence of photo-bleaching or tissue damage was seen intraoperatively in areas in which the fluorescent light was used. Conclusions: This technique may further improve 5-ALA’s utility in identifying tumor infiltrated tissue for deep-seated lesions. Additionally, this tool may have implications for standardizing the intensity of the blue light exposure on tissues when assessing or quantifying the 5-ALA fluorescence intensity.