Using Speckle to Measure Tissue Dispersion in Optical Coherence Tomography

In Optical Coherence tomography (OCT), dispersion mismatches cause degradation of the image resolution. However, dispersion is specific to the material that is causing the effect and can therefore carry useful information regarding the composition of the samples. In this summary, we propose a novel technique for estimating the dispersion in tissue which uses the image speckle to calculate the PSF degradation and is therefore applicable to any tissue and can be implemented in vivo and in situ. A Wiener-type deconvolution algorithm was used to estimate the image PSF degradation from the speckle. The proposed method was verified ex vivo resulting in comparable values of the Group Velocity Dispersion (GVD) as obtained by a standard estimation technique described in the literature. The applicability to cancer diagnosis was evaluated on a small set of gastrointestinal normal and cancer OCT images. Using the statistics of the GVD estimate, the tissue classification resulted in 93% sensitivity and 73% specificity (84% correct classification rate). The success of these preliminary results indicates the potential of the proposed method which should be further investigated to elucidate its advantages and limitations.