338 results found
Avila-Rencoret FB, Mylonas GP, Elson DS, 2018, Robotic wide-field optical biopsy endoscopy
© OSA 2018. This paper describes a novel robotic framework for wide-field optical biopsy endoscopy, characterizes in vitro its spatial and spectral resolution, real time hyperspectral tissue classification, and demonstrates its feasibility on fresh porcine cadaveric colon.
Deng L, Yan JD, Elson DS, et al., 2018, Characterization of an imaging multimode optical fiber using a digital micro-mirror device based single-beam system, Optics Express, Vol: 26, Pages: 18436-18447, ISSN: 1094-4087
This work demonstrates experimental approaches to characterize a single multimode fiber imaging system without a reference beam. Spatial light modulation is performed with a digital micro-mirror device that enables high-speed binary amplitude modulation. Intensity-only images are recorded by the camera and processed by a Bayesian inference based algorithm to retrieve the phase of the output optical field as well as the transmission matrix of the fiber. The calculated transmission matrix is validated by three standards: prediction accuracy, transmission imaging, and focus generation. Also, it is found that information on mode count and eigenchannels can be extracted from the transmission matrix by singular value decomposition. This paves the way for a more compact and cheaper single multimode fiber imaging system for many demanding imaging tasks.
Lin J, Clancy NT, Qi J, et al., 2018, Dual-modality endoscopic probe for tissue surface shape reconstruction and hyperspectral imaging enabled by deep neural networks., Med Image Anal, Vol: 48, Pages: 162-176
Surgical guidance and decision making could be improved with accurate and real-time measurement of intra-operative data including shape and spectral information of the tissue surface. In this work, a dual-modality endoscopic system has been proposed to enable tissue surface shape reconstruction and hyperspectral imaging (HSI). This system centers around a probe comprised of an incoherent fiber bundle, whose fiber arrangement is different at the two ends, and miniature imaging optics. For 3D reconstruction with structured light (SL), a light pattern formed of randomly distributed spots with different colors is projected onto the tissue surface, creating artificial texture. Pattern decoding with a Convolutional Neural Network (CNN) model and a customized feature descriptor enables real-time 3D surface reconstruction at approximately 12 frames per second (FPS). In HSI mode, spatially sparse hyperspectral signals from the tissue surface can be captured with a slit hyperspectral imager in a single snapshot. A CNN based super-resolution model, namely "super-spectral-resolution" network (SSRNet), has also been developed to estimate pixel-level dense hypercubes from the endoscope cameras standard RGB images and the sparse hyperspectral signals, at approximately 2 FPS. The probe, with a 2.1 mm diameter, enables the system to be used with endoscope working channels. Furthermore, since data acquisition in both modes can be accomplished in one snapshot, operation of this system in clinical applications is minimally affected by tissue surface movement and deformation. The whole apparatus has been validated on phantoms and tissue (ex vivo and in vivo), while initial measurements on patients during laryngeal surgery show its potential in real-world clinical applications.
Qi J, He H, Lin J, et al., 2018, Assessment of tissue polarimetric properties using Stokes polarimetric imaging with circularly polarized illumination, JOURNAL OF BIOPHOTONICS, Vol: 11, ISSN: 1864-063X
Saso S, Clancy NT, Jones BP, et al., 2018, Use of biomedical photonics in gynecological surgery: a uterine transplantation model., Future Sci OA, Vol: 4, ISSN: 2056-5623
Aim: Uterine transplantation (UTx) has been proposed as a treatment for permanent absolute uterine factor infertility. The study aims were to compare pulse oximetry and multispectral imaging (MSI), for intraoperative tracking of uterine oxygen saturation in animal UTx models (rabbit and sheep). Results/methodology: Imaging results confirmed the re-establishment of adequate perfusion in the transplanted organ after surgery. Comparison of oxygen saturation values between the pre-UTx donor and post-UTx recipient, and pre-UTx and post-UTx recipient reveals a statistically significant decrease in saturation levels post-UTx. Conclusion: The use of MSI is the first case in gynecology and has demonstrated promise of possible future human use. MSI technique has advantages over pulse oximetry - it provides spatial information in a real-time, noncontact manner.
Song L, Wang X, Zhang R, et al., 2018, Improving temporal resolution and speed sensitivity of laser speckle contrast analysis imaging based on noise reduction with an anisotropic diffusion filter, JOURNAL OF OPTICS, Vol: 20, ISSN: 2040-8978
Wirkert SJ, Vemuri AS, Kenngott HG, et al., 2018, Physiological parameter estimation from multispectral images unleashed, ISSN: 1431-472X
© Springer-Verlag GmbH Deutschland 2018. Multispectral imaging in laparoscopy can provide tissue reflectance measurements for each point in the image at multiple wavelengths of light. These reflectances encode information on important physiological parameters not visible to the naked eye. Fast decoding of the data during surgery, however, remains challenging.
Clancy NT, Elson DS, Teare J, 2017, Hyperspectral imaging of colonic polyps in vivo (Conference Presentation), Conference on Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XV, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Dong Y, Qi J, He H, et al., 2017, Quantitatively characterizing the microstructural features of breast ductal carcinoma tissues in different progression stages by Mueller matrix microscope, BIOMEDICAL OPTICS EXPRESS, Vol: 8, Pages: 3643-3655, ISSN: 2156-7085
Elson DS, 2017, Polarization-resolved endoscopy for image-guided surgery
Harris-Birtill D, Singh M, Zhou Y, et al., 2017, Gold nanorod reshaping in vitro and in vivo using a continuous wave laser., PLoS ONE, Vol: 12, ISSN: 1932-6203
Gold nanorods (GNRs) are increasingly being investigated for cancer theranostics as they possess features which lend themselves in equal measures as contrast agents and catalysts for photothermal therapy. Their optical absorption spectral peak wavelength is determined by their size and shape. Photothermal therapy using GNRs is typically established using near infrared light as this allows sufficient penetration into the tumour matrix. Continuous wave (CW) lasers are the most commonly applied source of near infrared irradiation on GNRs for tumour photothermal therapy. It is perceived that large tumours may require fractionated or prolonged irradiation. However the true efficacy of repeated or protracted CW irradiation on tumour sites using the original sample of GNRs remains unclear. In this study spectroscopy and transmission electron microscopy are used to demonstrate that GNRs reshape both in vitro and in vivo after CW irradiation, which reduces their absorption efficiency. These changes were sustained throughout and beyond the initial period of irradiation, resulting from a spectral blue-shift and a considerable diminution in the absorption peak of GNRs. Solid subcutaneous tumours in immunodeficient BALB/c mice were subjected to GNRs and analysed with electron microscopy pre- and post-CW laser irradiation. This phenomenon of thermally induced GNR reshaping can occur at relatively low bulk temperatures, well below the bulk melting point of gold. Photoacoustic monitoring of GNR reshaping is also evaluated as a potential clinical aid to determine GNR absorption and reshaping during photothermal therapy. Aggregation of particles was coincidentally observed following CW irradiation, which would further diminish the subsequent optical absorption capacity of irradiated GNRs. It is thus established that sequential or prolonged applications of CW laser will not confer any additional photothermal effect on tumours due to significant attenuations in the peak optical absorpt
Janatka M, Ramdoo KS, Tatla T, et al., 2017, Examining in vivo Tympanic Membrane Mobility Using Smart Phone Video-Otoscopy and Phase-based Eulerian Video Magnification, Conference on Medical Imaging - Computer-Aided Diagnosis, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Jones G, Clancy NT, Du X, et al., 2017, Fast estimation of haemoglobin concentration in tissue via wavelet decomposition, Pages: 100-108, ISSN: 0302-9743
© Springer International Publishing AG 2017. Tissue oxygenation and perfusion can be an indicator for organ viability during minimally invasive surgery, for example allowing real-time assessment of tissue perfusion and oxygen saturation. Multispectral imaging is an optical modality that can inspect tissue perfusion in wide field images without contact. In this paper, we present a novel, fast method for using RGB images for MSI, which while limiting the spectral resolution of the modality allows normal laparoscopic systems to be used. We exploit the discrete Haar decomposition to separate individual video frames into low pass and directional coefficients and we utilise a different multispectral estimation technique on each. The increase in speed is achieved by using fast Tikhonov regularisation on the directional coefficients and more accurate Bayesian estimation on the low pass component. The pipeline is implemented using a graphics processing unit (GPU) architecture and achieves a frame rate of approximately 15 Hz. We validate the method on animal models and on human data captured using a da Vinci stereo laparoscope.
Jones G, Clancy NT, Helo Y, et al., 2017, Bayesian Estimation of Intrinsic Tissue Oxygenation and Perfusion From RGB Images, IEEE TRANSACTIONS ON MEDICAL IMAGING, Vol: 36, Pages: 1491-1501, ISSN: 0278-0062
Lin J, Clancy NT, Hu Y, et al., 2017, Endoscopic depth measurement and super-spectral-resolution imaging, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Vol: 10434 LNCS, Pages: 39-47, ISSN: 0302-9743
© Springer International Publishing AG 2017. Intra-operative measurements of tissue shape and multi/hyperspectral information have the potential to provide surgical guidance and decision making support. We report an optical probe based system to combine sparse hyperspectral measurements and spectrally-encoded structured lighting (SL) for surface measurements. The system provides informative signals for navigation with a surgical interface. By rapidly switching between SL and white light (WL) modes, SL information is combined with structure-from-motion (SfM) from white light images, based on SURF feature detection and Lucas-Kanade (LK) optical flow to provide quasi-dense surface shape reconstruction with known scale in real-time. Furthermore, “super-spectral-resolution” was realized, whereby the RGB images and sparse hyperspectral data were integrated to recover dense pixel-level hyperspectral stacks, by using convolutional neural networks to upscale the wavelength dimension. Validation and demonstration of this system is reported on ex vivo/in vivo animal/human experiments.
Ong ZY, Chen S, Nabavi E, et al., 2017, Multibranched Gold Nanoparticles with Intrinsic LAT-1 Targeting Capabilities for Selective Photothermal Therapy of Breast Cancer, ACS APPLIED MATERIALS & INTERFACES, Vol: 9, Pages: 39259-39270, ISSN: 1944-8244
Qi J, Elson DS, 2017, Mueller polarimetric imaging for surgical and diagnostic applications: a review, JOURNAL OF BIOPHOTONICS, Vol: 10, Pages: 950-982, ISSN: 1864-063X
Qi J, He C, Elson DS, 2017, Real time complete Stokes polarimetric imager based on a linear polarizer array camera for tissue polarimetric imaging, BIOMEDICAL OPTICS EXPRESS, Vol: 8, Pages: 4933-4946, ISSN: 2156-7085
Qi J, He H, Ma H, et al., 2017, Extended polar decomposition method of Mueller matrices for turbid media in reflection geometry, OPTICS LETTERS, Vol: 42, Pages: 4048-4051, ISSN: 0146-9592
Qi J, Nabavi E, Hu Y, et al., 2017, A light-weight near infrared fluorescence endoscope based on a single color camera: a proof-of-concept study, Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR), Publisher: IEEE
Shah PL, Kemp SV, Newton RC, et al., 2017, Clinical Correlation between Real-Time Endocytoscopy, Confocal Endomicroscopy, and Histopathology in the Central Airways, RESPIRATION, Vol: 93, Pages: 51-57, ISSN: 0025-7931
Tonutti M, Elson DS, Yang G-Z, et al., 2017, The role of technology in minimally invasive surgery: state of the art, recent developments and future directions, POSTGRADUATE MEDICAL JOURNAL, Vol: 93, Pages: 159-167, ISSN: 0032-5473
Wirkert SJ, Vemuri AS, Kenngott HG, et al., 2017, Physiological parameter estimation from multispectral images unleashed, Pages: 134-141, ISSN: 0302-9743
© Springer International Publishing AG 2017. Multispectral imaging in laparoscopy can provide tissue reflectance measurements for each point in the image at multiple wavelengths of light. These reflectances encode information on important physiological parameters not visible to the naked eye. Fast decoding of the data during surgery, however, remains challenging. While model-based methods suffer from inaccurate base assumptions, a major bottleneck related to competing machine learning-based solutions is the lack of labelled training data. In this paper, we address this issue with the first transfer learning-based method to physiological parameter estimation from multispectral images. It relies on a highly generic tissue model that aims to capture the full range of optical tissue parameters that can potentially be observed in vivo. Adaptation of the model to a specific clinical application based on unlabelled in vivo data is achieved using a new concept of domain adaptation that explicitly addresses the high variance often introduced by conventional covariance-shift correction methods. According to comprehensive in silico and in vivo experiments our approach enables accurate parameter estimation for various tissue types without the need for incorporating specific prior knowledge on optical properties and could thus pave the way for many exciting applications in multispectral laparoscopy.
Zhang Y, Wirkert SJ, Iszatt J, et al., 2017, Tissue classification for laparoscopic image understanding based on multispectral texture analysis, JOURNAL OF MEDICAL IMAGING, Vol: 4, ISSN: 2329-4302
Clancy NT, Saso S, Stoyanov D, et al., 2016, Multispectral imaging of organ viability during uterine transplantation surgery in rabbits and sheep, JOURNAL OF BIOMEDICAL OPTICS, Vol: 21, ISSN: 1083-3668
Clancy NT, Teare J, Hanna GB, et al., 2016, Flexible multimode endoscope for tissue reflectance and autofluorescence hyperspectral imaging
© OSA 2016. A dual reflectance and autofluorescence spectral imaging probe compatible with the biopsy channels of standard flexible endoscopes is demonstrated. Spatially-resolved haemoglobin and autofluorescent signals from porcine bowel were obtained in vivo.
© OSA 2016. We present an in vivo study of endoscopic fluorescence image-guided photothermal therapy of human oesophageal adenocarcinoma in a murine xenograft model, using intratumoural or intravenous gold nanorods functionalised with Cy5.5 and EGFR.
Elson DS, 2016, Endoscopic image-guided thermal therapy using targeted near infrared fluorescent gold nanorods, Conference on Biosensing and Nanomedicine IX, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Gallina ME, Zhou Y, Johnson CJ, et al., 2016, Aptamer-conjugated, fluorescent gold nanorods as potential cancer theradiagnostic agents, MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS, Vol: 59, Pages: 324-332, ISSN: 0928-4931
Jones G, Clancy NT, Arridge S, et al., 2016, Inference of tissue haemoglobin concentration from Stereo RGB, Pages: 50-58, ISSN: 0302-9743
© Springer International Publishing Switzerland 2016. Multispectral imaging (MSI) can provide information about tissue oxygenation, perfusion and potentially function during surgery. In this paper we present a novel, near real-time technique for intrinsic measurements of total haemoglobin (THb) and blood oxygenation (SO2) in tissue using only RGB images from a stereo laparoscope. The high degree of spectral overlap between channels makes inference of haemoglobin concentration challenging, non-linear and under constrained. We decompose the problem into two constrained linear sub-problems and show that with Tikhonov regularisation the estimation significantly improves, giving robust estimation of the THb. We demonstrate by using the coregistered stereo image data from two cameras it is possible to get robust SO2estimation as well. Our method is closed from, providing computational efficiency even with multiple cameras. The method we present requires only spectral response calibration of each camera, without modification of existing laparoscopic imaging hardware. We validate our technique on synthetic data from Monte Carlo simulation and further, in vivo, on a multispectral porcine data set.
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