Time-Domain Polarization-Sensitive Optical Coherence Tomography in Soft Biological Tissue

摘要

A new, high-speed, fiber-based Mueller-matrix optical coherence tomographysystem with continuous source-polarization modulation is presented. For in vivoexperimentation, the sample arm optics are integrated into a hand-held probe. Thesystem?s parameters were verified through imaging standard optical elements. A uniquefeature of polarization-sensitive Mueller optical coherence tomography is that bymeasuring Jones or Mueller matrices, it can reveal the complete polarization propertiesof biological samples, even in the presence of diattenuation. Presented here for the firsttime are mapped local polarization properties of biological samples obtained by usingpolar decomposition in combination with least-squares fitting to differentiate measuredintegrated Jones matrices with respect to depth. In addition, a new concept of dualattenuation coefficients to characterize diattenuation per unit infinitesimal length intissues is introduced. The algorithm was experimentally verified using measurements ofa section of porcine tendon and the septum of a rat heart. The application of the system for burn imaging and healing monitoring wasdemonstrated on porcine skin because of its similarity to the human skin. The resultsshowed a clear localization of the thermally damaged region. The local birefringence ofthe intravital porcine skin was mapped by using a differentiation algorithm. The burnareas in the OCT images agree well with the histology, thus demonstrating the system?spotential for burn-depth determination and post-injury healing monitoring.Another major application of the fiber-based Mueller-matrix optical coherencetomography system with continuous source-polarization modulation covered here is invivo imaging of early stages of skin cancer. The OCT images of SENCAR mice skinaffected by the tumorigenesis show the structural changes in skin resulting from precancerouspapilloma formations that are consistent with histology, which proves thesystem?s potential for early skin cancer detection.