Optical coherence tomography (OCT) yields microscopic volumetric images representing tissue structures based on the contrast provided by elastic light scattering. Multipatient studies using OCT for detection of tissue abnormalities can lead to large datasets making quantitative and unbiased assessment of classification algorithms performance difficult without the availability of automated analytical schemes. We present a mathematical descriptor reducing the dimensionality of a classifier’s input data, while preserving essential volumetric features from reconstructed three-dimensional optical volumes. This descriptor is used as the input of classification algorithms allowing a detailed exploration of the features space leading to optimal and reliable classification models based on support vector machine techniques. Using imaging dataset of paraffin-embedded tissue samples from 38 ovarian cancer patients, we report accuracies for cancer detection >90% for binary classification between healthy fallopian tube and ovarian samples containing cancer cells. Furthermore, multiples classes of statistical models are presented demonstrating >70% accuracy for the detection of high-grade serous, endometroid, and clear cells cancers. The classification approach reduces the computational complexity and needed resources to achieve highly accurate classification, making it possible to contemplate other applications, including intraoperative surgical guidance, as well as other depth sectioning techniques for fresh tissue imaging.
The majority of high-grade serous ovarian cancers is now believed to originate in the fallopian tubes. Therefore, current practices include the pathological examination of excised fallopian tubes. Detection of tumors in the fallopian tubes using current clinical approaches remains difficult but is of critical importance to achieve accurate staging and diagnosis. Here, we present an intraoperative imaging system for the detection of human fallopian tube lesions. The system is based on optical coherence tomography (OCT) to access subepithelial tissue architecture. To demonstrate that OCT could identify lesions, we analyzed 180 OCT volumes taken from five different ovarian lesions and from healthy fallopian tubes, and compared them to standard pathological review. We demonstrated that qualitative features could be matched to pathological conditions. We then determined the feasibility of intraluminal imaging of intact human fallopian tubes by building a dedicated endoscopic single-fiber OCT probe to access the mucosal layer inside freshly excised specimens from five patients undergoing prophylactic surgeries. The probe insertion into the lumen acquired images over the entire length of the tubes without damaging the mucosa, providing the first OCT images of intact human fallopian tubes.
While thyroidectomy is considered a safe surgery, dedicated tools facilitating tissue identification during surgery could improve its outcome. The most common complication following surgery is hypocalcaemia, which results from iatrogenic removal or damage to parathyroid glands. This research project aims at developing and validating an instrument based on optical microscopy modalities to identify tissues in real time during surgery.
Our approach is based on a combination of reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) to obtain multi-scale morphological contrast images. The orthogonal field of views provide information to navigate through the sample.
To allow simultaneous, synchronized video-rate imaging in both modalities, we designed and built a dual-band wavelength-swept laser which scans a 30 nm band centered at 780 nm and a 90 nm band centered at 1310 nm. We built an imaging setup integrating a custom-made objective lens and a double-clad fibre coupler optimized for confocal microscopy. It features high resolutions in RCM (2µm lateral and 20 µm axial) in a 500 µm x 500 µm field-of-view and a larger field-of-view of 2 mm (lateral) x 5 mm (axial) with 20 µm lateral and axial resolutions in OCT.
Imaging of ex vivo animal samples is demonstrated on a bench-top system. Tissues that are visually difficult to distinguish from each other intra-operatively such as parathyroid gland, lymph nodes and adipose tissue are imaged to show the potential of this approach in differentiating neck tissues. We will also provide an update on our ongoing clinical pilot study on patients undergoing thyroidectomy.
Pathological evaluation of the fallopian tubes is an important diagnostic result but tumors can be missed using routine approaches. As the majority of high-grade serous ovarian cancers are now believed to originate in the fallopian tubes, pathological examination should include in a thorough examination of the excised ovaries and fallopian tubes. We present an dedicated imaging system for diagnostic exploration of human fallopian tubes. This system is based on optical coherence tomography (OCT), a laser imaging modality giving access to sub- epithelial tissue architecture. This system produces cross-sectional images up to 3 mm in depth, with a lateral resolution of ≈15μm and an axial resolution of ≈12μm. An endoscopic single fiber probe was developed to fit in a human fallopian tube. This 1.2 mm probe produces 3D volume data of the entire inner tube within a few minutes. To demonstrate the clinical potential of OCT for lesion identification, we studied 5 different ovarian lesions and healthy fallopian tubes. We imaged 52 paraffin-embedded human surgical specimens with a benchtop system and compared these images with histology slides. We also imaged and compared healthy oviducts from 3 animal models to find one resembling the human anatomy and to develop a functional ex vivo imaging procedure with the endoscopic probe. We also present an update on an ongoing clinical pilot study on women undergoing prophylactic or diagnostic surgery in which we image ex vivo fallopian tubes with the endoscopic probe.
In this paper we propose and demonstrate two forms of a device for sensing cladding modes efficiently. The cladding modes, generated by an untilted and tilted fibre Bragg grating (TFBG) written in SMF28 fibre are captured by splicing it to an in-line double-clad fibre coupler (DCFC). A comaprison is made of the capture efficiency of the cladding modes in two configurations; one in which the TFBG is taper spliced to the DCF, or in the other in which an FBG in an SMF28 is etched down to match the outer core of the DCF. In both cases the cladding modes are captured efficiently, but with significantly improved results for the former configuration. We demonstrate surrounding refractive index sensing using a new signal analysis scheme based on the extinction of each cladding mode resolved over a bandwidth of over ~60nm. This robust device has the advantage of faithfully transmitting the cladding modes over a long distance and is therefore suitable for remote sensing over long distances. The sensitivity of the device is discussed. This device may be used in a variety of applications such as for bend, strain, temperature and surrounding refractive index sensing.
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