OPTICAL SIMULATIONS OF A NONINVASIVE TECHNIQUE FOR THE DIAGNOSIS OF DISEASED SALIVARY-GLANDS IN-SITU

A simulation experiment for three-dimensional (3D) imaging of exogenou s fluorescinated antibodies that specifically bind to infiltrating lym phocytes in minor salivary glands was carried out. Small (similar to 1 mm(3) volume) rhodamine targets, which mimic diseased minor salivary glands labeled with fluorescent antibodies to infiltrating lymphocytes in Sjogren's syndrome, were embedded in a highly scattering tissue ph antom consisting of a thick Delrin(TM) disk covered by index matched D elrin(TM) slabs of various thickness. In this way the variation of flu orescence profiles on the surface of tissue could be examined correspo nding to the range of depths of the salivary glands in vivo. Surface i mages were obtained for different target depths and radial distances f rom laser excitation to target fluorophore. These images were analyzed and compared to calculations based on random walk theory in turbid me dia, using previously determined scattering and absorption coefficient s of the Delrin(TM). Excellent agreement between the surface profiles experimentally measured and those predicted by our random walk theory was obtained. Derivation of these theoretical expressions is a necessa ry step toward devising an inverse algorithm which may have the potent ial expressions to perform 3D reconstruction of the concentration dist ribution of fluorescent labels within tissue. (C) 1998 American Associ ation of Physicists in Medicine.