Microscopia multifótons em tecidos biológicos

Abstract

There is currently no quantitative method for the diagnosis of prostate cancer. In order to make the diagnosis, pathologists use a histological pattern of graduation that is related to the morphology of glands (acini) present in the biopsy and in the organization of the connective tissue around the gland that is known as the Gleason pattern. The method is subjective and depends heavily on the experience and training of the pathologist. With the recent advance in the development of femtosecond laser, non-linear optical microscopy, in special Second Harmonic Generation (SHG), has became a powerful tool in helping to diagnose diseases. One important development would be the use of the SHG microscopy as a quantitative tool for the diagnosis of cancer. In this work we present studies of prostate biopsies through multiphoton microscopies with the purpose of obtaining cancer diagnosis. We show results obtained through SHG images of collagen fibers and fluorescence images in biopsies collected from patients treated at Hospital das Clínicas da UFMG. The samples were drawn from different positions of the prostate, with diagnosis as follows: normal, benign prostatic hyperplasia and several malignancy of cancer. We present a method of image analysis based on the calculation of anisotropy of collagen fibers. The analysis show differences in the alignment of collagen fibers around the acini which are altered with the aggressiveness of cancer. Measuring the anisotropy (degree of alignment) of the collagen fibers we show that the higher the degree of malignancy of prostate cancer the greater the tendency of collagen fibers to become aligned around the glands. These results correlate directly with the Gleason score, which is the standard method used by pathologists for diagnosis.