Measuring Tissue Dispersion Using Optical Coherence Tomography Speckle

Dispersion mismatch between the two arms of an Optical Coherence Tomography (OCT) interferometer causes degradation of the image resolution. However, dispersion in tissue is specific to the chemical constituents of the cells and can therefore carry diagnostically useful information. Unfortunately, dispersion measurement techniques, presented so far in the literature, require the presence of strong distinct reflections in the OCT image which are rarely present when imaging tissues in vivo. The novel method presented here relies on the image speckle to calculate the PSF degradation and is therefore applicable to any tissue and can be implemented in vivo and in situ. The resolution degradation is estimated using a Wiener-type deconvolution and was verified ex vivo resulting in Group Velocity Dispersion (GVD) values comparable to the standard techniques. This technique has also been applied to normal and malignant samples of human colon to evaluate its applicability for cancer diagnosis. Using the statistics of the GVD estimate, the tissue classification resulted in 93% sensitivity and 100% specificity (96% correct classification rate). The success of these preliminary results indicates the potential of the proposed method which should be further