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Multimodal imaging platforms offer a vast array of tissue information in a single image acquisition by combining complementary imaging techniques. By merging different systems, better tissue characterization can be achieved than is possible by the constituent imaging modalities alone. The combination of optical coherence tomography (OCT) with non-linear optical imaging (NLOI) techniques such as two-photon excited fluorescence (TPEF), second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) provides access to detailed information of tissue structure and molecular composition in a fast, label-free and non-invasive manner. We introduce a multimodal label-free approach for morpho-molecular imaging and spectroscopy and validate the system in mouse skin demonstrating the potential of the system for colocalized acquisition of OCT and NLOI signals.

Using optical coherence tomography (OCT) intraoperatively for pituitary gland and adenoma differentiation, might lead to a more distinct resection of tumor tissue. Therefore, more gland tissue would be preserved and invasively grown adenoma tissue can be detected and removed. We evaluate the feasibility of laser scanning microscope based OCT for differentiation of healthy and tumor tissue on biopsies resected during surgery. The OCT images are compared to histopathological results. Resolution reduced OCT images are automatically analyzed to estimate the performance parameters for a possible endoscopic translation.

In this work, we present a significant step toward in vivo ophthalmic optical coherence tomography and angiography on a photonic integrated chip. The diffraction gratings used in spectral-domain optical coherence tomography can be replaced by photonic integrated circuits comprising an arrayed waveguide grating. Two arrayed waveguide grating designs with 256 channels were tested, which enabled the first chip-based optical coherence tomography and angiography in vivo three-dimensional human retinal measurements. Design 1 supports a bandwidth of 22 nm, with which a sensitivity of up to 91 dB (830 µW) and an axial resolution of 10.7 µm was measured. Design 2 supports a bandwidth of 48 nm, with which a sensitivity of 90 dB (480 µW) and an axial resolution of 6.5 µm was measured. The silicon nitride-based integrated optical waveguides were fabricated with a fully CMOS-compatible process, which allows their monolithic co-integration on top of an optoelectronic silicon chip. As a benchmark for chip-based optical coherence tomography, tomograms generated by a commercially available clinical spectral-domain optical coherence tomography system were compared to those acquired with on-chip gratings. The similarities in the tomograms demonstrate the significant clinical potential for further integration of optical coherence tomography on a chip system., Optical coherence tomography: chip promise The goal of an optical coherence tomography (OCT) imaging system that is integrated on a photonic chip has taken a step closer to reality. Elisabet Rank and coworkers from Austria have shown that arrayed waveguide gratings (AWGs), integrated-optical devices commonly used to separate different wavelength channels in an optical communications system, can be used to replace diffraction gratings in an OCT system. Several designs of silicon nitride AWGs with 256 channels in the near-infrared were fabricated and then tested in an OCT system which was able to capture in-vivo tomograms and angiography of the human eye’s retina, with comparable quality to a conventional system. The next stage of the OCT-on-a-chip research will focus on exploring the use of multimode interference structures, integrated photodiodes, and compact light sources.

Ultrahigh resolution optical coherence tomography (UHR-OCT) for differentiating pituitary gland versus adenoma tissue has been investigated for the first time, indicating more than 80% accuracy. For biomarker identification, OCT images of paraffin embedded tissue are correlated to histopathological slices. The identified biomarkers are verified on fresh biopsies. Additionally, an approach, based on resolution modified UHR-OCT ex vivo data, investigating optical performance parameters for the realization in an in vivo endoscope is presented and evaluated. The identified morphological features–cell groups with reticulin framework–detectable with UHR-OCT showcase a promising differentiation ability, encouraging endoscopic OCT probe development for in vivo application.

Our study targets improved and accelerated diagnostics of bladder cancer with optical coherence tomography (OCT) and Raman spectroscopy (RS) ex vivo. OCT provides structural information on the penetration depth of the lesion, whereas RS complements this information with molecular characteristics regarding the likelihood of growth and spreading. Hence, the diagnostic findings include the determination of stage and grade of a tumor. The bladder specimens were scanned with OCT to detect suspicious lesions. Thereby, OCT was used as a red-flag technology to examine the bladder wall for abnormal tissue. Malignant bladder wall could be discriminated from healthy tissue. Upon identification of a cancerous lesion, RS added diagnostic information with molecular characteristics of the tumor regarding the grade. Texture analysis of OCT tomograms followed by k-nearest neighbour classification determined the stage of the lesion. Principal component analysis (PCA) of Raman spectra allowed for dimension reduction which was also fed into a k-nearest neighbour classifier allowing for classification of low-grade and high-grade tumors. We obtained an accuracy of 71% and 93% for staging and grading, respectively.