NON-INVASIVE TUMOR DETECTION USING SPECTRALLY-RESOLVED IN VIVO IMAGING Genady Kostenichl*, Sol Kimel', Zvi Malik2 and Arie Orenstein' 'Advanced Technology Center, Sheba Medical Center, 52621 Tel Hashomer, 2Life Sciences Department, Bar han University, 52900 Ramat-Gan, Israel ABSTRACT A novel spectral image-analysis system was used for tumor fluorescence and reflectance imaging in an animal model and in patients. Transcutaneous fluorescence imaging was carried out on Balb/c mice bearing subcutaneous C26 colon carcinoma after intraperitoneal (i.p.) administration of 5-aminolevulinic acid (ALA), a metabolic precursor of protoporphyrin-IX (PP), and of a novel photosensitizer tetrahydroporphyrin (THP). Tumors were clearly observable by fluorescence detection using green light excitation. Tumor versus normal tissue uptake of the photosensitizing agents was determined by monitoring fluorescence intensity. Maximal PP accumulation in tumor was observed 3 h after i.p. injection of ALA, whereas THP showed selective accumulation in tumor 24 h after administration. Reflectance spectroscopy was employed to study pigmented human skin lesions (nevus, pigmented BCC and pigmented melanoma). In the near-infrared region (800-880 nm) pigmented BCC and melanoma exhibited a differently shaped reflectance spectrum compared to normal skin and nevus. Spatially and spectrally resolved imaging, in combination with mathematical algorithms (such as normalization, spectral similarity mapping and division) allowed unambiguous detection of malignancies. Optical biopsy results from a total of 51 patients showed 45 benign nevi, 3 pigmented BCC and 3 malignant melanomas, as confirmed by histology. Keywords: Melanoma, pigmented basal cell carcinoma, benign nevus, Fourier transform spectroscopy, near-infrared reflectance 1. INTRODUCTION Early detection of cancer and diagnostic accuracy are essential for successful treatment. Most diagnostic and prognostic assessments in-vivo, before or during surgery or therapy, are done by reliance on the experience of the pathologist or surgeon. The result of this analysis will often have a significant impact on the quality of life of the patient as it can save many years of suffering for the patient. Non-invasive optical methods have great potential as alternative diagnostic modalities. Malignant tissues have optical properties that are different from normal tissue. Since spectroscopic information is related to the physical and chemical composition ofmatter, it provides information on tissue, when the tissue can be exposed to light. Malignant melanoma, the most aggressive and dangerous type of skin cancer, was detected by visual observation, dermatoscopy or computerized systems based on assessment of the asymmetry, border, color and dimension (ABCD) criteria. It has been shown that an optical method such as reflectance imaging in a defined spectral range (near-infrared, NIR) can improve melanoma detection'3. Indeed, recent spectrophotometric measurements of pigmented skin lesions revealed differences in the visible and NIR spectral regions between malignant melanoma and benign nevi '. In the present study we used a novel system based on Fourier transform spectral imaging. Multi-spectral imaging spectroscopy can be put to use to identify and quantify biologically active molecules, thus indicating the presence of cancer. Reflectance imaging spectroscopy was employed to study pigmented human skin lesions (nevus, pigmented Basal Cell Carcinoma and malignant melanoma). Optical Biopsy and Tissue Optics, Irving J. Bigio, Gerhard J. Müller, Gerwin J. Puppels, Rudolf W. Steiner, Katarina Svanberg, Editors, Proceedings of SPIE Vol. 4161 (2000) © 2000 SPIE · 0277-786X/00/$15.00 244 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/17/2013 Terms of Use: http://spiedl.org/terms