PMC

Negative tumor margin. OCT (a) and corresponding H&E-stained histology (b) of normal breast tissue near the surface of a lumpectomy specimen. The large adipose cells with point-like scattering nuclei dominate the OCT image, which also contains a region of the microvasculature (arrows). Features found in the real-time intraoperative OCT image correspond well to those identified in the post-surgical paraffin-embedded histology section.

Clinical spectral-domain optical coherence tomography system schematic. Light from a SLD (λ=1310 nm) is directed into an optical circulator (OC) and to a fiber coupler (FC) which splits 5% of the light to a reference arm mirror (RM) and 95% of the light to a sample arm containing focusing optics and an automated x-y translation stage (TS). Light is collimated through fiber collimators (Col). Reflected light from each arm is coupled through polarization paddles (PP), interfered within the fiber coupler, and spectrally dispersed onto a line camera.

Photograph of the clinical SD-OCT system housed in a standard endoscopy cart (left). This system is portable for use in various surgical suites. Resected surgical specimens are placed on the sample-arm stage (a). The detector and reference arm (b) are located within the cart, along with the light source and hardware controllers (c) and computer (d). OCT images (shown in later figures) represent 2-D cross-sectional planes (x-z) oriented perpendicular to the tissue surface (right). Multiple OCT images can be acquired by stepping the beam in the y direction.

Representative OCT images of surgical margins from lumpectomy specimens acquired for the training set. Images of normal tissue (a) were identified by the homogenous pattern of large adipose cells. Readily identified surgical artifacts include blood (b) which appears as a thin film of scatterers, and cauterized tissue (c) which has a patch-like appearance. Images of positive margins (d) containing tumor cells and tissue included a highly scattering area that was more heterogeneous and disruptive of the surrounding architecture.

Positive tumor margins. OCT images (a, c) show a distinct heterogeneously-scattering region (arrows) with small, highly scattering foci indicative of collections of tumor cells. These features clearly extend to the surface of the specimen (to the surgical margin) in (a) and the left side of (c), but also are evident below adipose tissue in (c). The OCT image in (a) was acquired with a coverslip over the surface to reduce backreflection artifacts, which appear as vertical lines in (c). Corresponding H&E-stained histology (b, d) images show corresponding features, confirming the presence of these positive margins.