Purpose
Fluorescein-guided resection of tumors is a relatively new modality being used in neurosurgery and urology, with recent literature describing the ability to obtain clearer margins. However, current knowledge on direct staining characteristics in various tissue types is limited at best. Herein, we investigate the staining properties of vital dyes to advance our knowledge for potential use during in vivo resection of tumors.
Methods
4 vital dyes were prepared into aqueous solutions of 2 concentrations: either 1 mg/ml and 0.5 mg/ml concentrations (fluorescein, lissamine green, and rose bengal) or 0.1% and 0.06% (trypan blue.) Sprague-Dawley rats were used to harvest periorbital tissues of interest: muscle, adipose, optic nerve, brain and meninges. Tissue samples were stained with the dyes for 2 minutes then washed with 3 saline baths (3 x 5 mins) to determine the amount of residual staining. Color photographs were taken prior to staining, after staining, and after saline washes.
Results
Muscle, adipose, nerve and meninges appeared to stain relatively strongly with each dye, with visibly significant retention of stain after saline washing. Brain had variable but often minimal preliminary staining with the dyes; however, it appeared to have little to no retention of stain. All of the vital dyes appeared to stain meninges quite strongly, with little appreciable loss of dye. Of the 4 vital stains, lissamine green was the poorest at both initial and retained staining. Rose bengal appeared to be the most resilient stain of the 4, with minimal dissipation of dye after washing of the tissues.
Conclusions
With respect to vital dye utility for in vivo tumor resection, the most promising finding of our investigation is the visible disparity in staining between brain and meningeal tissue, with minimal uptake of the vital dyes in brain tissue. This predilection for staining in meningeal tissue would be of most interest for resection of meningiomas, potentially offering clear delineation between brain and meningioma, allowing for maximal visualization of tumor and ideally greater preservation of healthy brain during surgery.
Keywords: 744 tumors •
637 pathology: experimental •
631 orbit