Compressional optical coherence elastography as a tool for feasible in vivo histology-like morphological segmentation of cancer-tissue constituents

Abstract

We report a new application of compressional optical coherence elastography (OCE) to discriminate morphological constituents of biological tissues by analyzing OCE images obtained either in vivo or for freshly excised samples. The new technique enables quantitative morphological segmentation of OCE images with delineation of several (~4-6) tissue constituents. As the first step, the method uses compressional OCE to reconstruct maps for a pre-chosen standardized pressure over the entire area of the OCE image. Then specific ranges (characteristic stiffness spectra) are initially determined by careful comparison of the OCE-based maps with the results of segmentation of gold-standard histological slices. After such pre-calibration, the maps can be automatically segmented into regions, for which the Young’s modulus (stiffness) falls in specific ranges corresponding to the morphological constituents to be discriminated. The results of such automated segmentation of OCE-images demonstrate a striking correlation with the results of conventional segmentation of histological slices in terms of percentages of the segmented zones. High sensitivity of the OCE-method to histological alterations was demonstrated in vivo in comparative studies of various types of anti-tumor therapies using murine tumor models. Studies of >100 samples of freshly excised breast cancer samples revealed strong correlation between the tumor-tissue subtype and its morphological composition determined by the developed OCE method. Thus, the developed approach can be used as a basis for express OCE-based biopsy (feasible intraoperatively). Longitudinal in vivo monitoring of morphological alterations in tumors under therapy or during natural development is also possible for locations accessible to OCT.