Intraoperative metastases detection by laser induced fluorescence spectroscopy (LIFS) S.G. Van, T.G. Papazoglou, N.J. van der Veen1, M.C. Fishbein, J. Young, N. Chandra, T. Papaioannou, C. Beeder, W.Q. Shi and w.s. Grundfest Laser Research Center, Cedars—Sinai Medical Center Los Angeles, California 90048 1School of Medicine, State University Utrecht, the Netherlands ABSTRACT We studied the ability of Laser Induced Fluorescence Spectroscopy (LIFS) for the intraoperative identification of metastases using a photosensitizing agent Photofrin 11r to enhance spectroscopic detection. A He—Cd laser source (442 nm) was used to produce low power illumination of tissue via a hand held 400 urn fiberoptic probe. Through the same fiber, reflected and emitted light was returned to an optical multi channel analyzer (OMA III) for analysis. Spectroscopic signals were displayed on a screen for immediate examination. Lobund Wistar rats, inoculated with Pollard rat adenocarcinoma cells, were used as an animal model. Photofrin hr was administrated intraperitoneal 24 or 48 hrs prior to surgical exploration in doses varying from 0.75-7.5 mg/kg. Metastases detection was performed during abdominal exploration directed to ipsilateral and contralateral inguinal, iliac, para—aortic and renal lymph nodes. Nineteen tissue samples, identified as abnormal by LIFS, were removed for histologic analysis; 11 of these samples were larger than 5mm and histologic examination revealed malignancy in all cases. While LIFS signals showed malignancy in 8 tissue samples with dimensions less than 5mm, histology confirmed this in only 3. However, serial histologic sections were not performed. FrOm our initial results, we conclude that LIFS detection of malignant tissue is feasible and enhanced by the addition of Photofrin 11r, LIFS may be a promising technique for the intraoperative detection of primary malignant and metastatic tissue. 1. INTRODUCTION For the past three decades it is known that Hematoporphyrin, or its various derivates (HpD) like Photofrin II, accumulate selectively in malignant tissue1,2,. Following specific laser irradiation, tissue with HpD shows a strong, red fluorescence signal allowing malignancy localization3. Another important feature of HpD is its cytotoxic effect following exposure to specific laser light that is used in Photodynamic Therapy (PDT)4. These two properties of HpD, its selectivity for tumors and its photosensitivity have been investigated since early 80's4,b. Photodynamic Therapy (PDT) has been studied in clinical trials (phase III) for many types of solid tumors, treating more than 2000 SPIE Vol. 1426 Optical Methods for Tumor Treatment and Early Diagnosis: Mechanisms and Techniques (1991) / 111 0-8194-0516-7/91 /$4.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/18/2013 Terms of Use: http://spiedl.org/terms