Laser-induced fluorescence detection of malignant gliomas using fluorescein-labeled serum albumin: Experimental and preliminary clinical results

To delineate the tumor margins of malignant gliomas laser-induced fluoresce nce detection technique was applied using 5-aminofluorescein-albumin as the fluorescent dye. The 5-aminofluorescein was linked to serum albumin (= AFl c-SA) as a cumulative protein label using residualizing markers. In a CG-gl ioma model the biodistribution and pharmacokinetics of the injected dye wer e investigated by labeling the protein conjugate with (111)ln-DTPA. Twenty- four hours after intravenous injection of the dye, fluorescence was activat ed by an argon laser and inspected in the C6-gliomas. Histological examinat ions were performed to compare the microscopic margins of the fluorescence- stained tumors with hematoxylin/eosin. The tumor uptake 24 h after dye inje ction was 23-fold higher than in the surrounding brain. Fluorescence inspec tion under laser activation demonstrated clearly stained and sharply demarc ated tumors. The microscopic borders of the tumors corresponded exactly wit h the fluorescence, also demonstrating intracellular tumor uptake of the dy e. In a preliminary study, three patients with malignant gliomas were opera ted using laser-induced fluorescence detection technique after injection of AFlc-SA. In all patients, the borders of the malignant gliomas were clearl y stained by AFlc-SA during surgery. Laser-induced fluorescence imaging usi ng the albumin conjugate AFlc-SA may be a promising method for delineating tumor margins which are hard to detect under the operating microscope alone .