395 results found
Qi J, Elson D, 2016, A high definition Mueller polarimetric endoscope for tissue characterisation, Scientific Reports, Vol: 6, ISSN: 2045-2322
The contrast mechanism of medical endoscopy is mainly based on metrics of optical intensity andwavelength. As another fundamental property of light, polarization can not only reveal tissuescattering and absorption information from a different perspective, but can also provide insight intodirectional tissue birefringence properties to monitor pathological changes in collagen and elastin.Here we demonstrate a low cost wide field high definition Mueller polarimetric endoscope with minimalalterations to a rigid endoscope. We show that this novel endoscopic imaging modality is able toprovide a number of image contrast mechanisms besides traditional unpolarized radiation intensity,including linear depolarization, circular depolarization, cross-polarization, directional birefringence anddichroism. This enhances tissue features of interest, and additionally reveals tissue micro-structure andcomposition, which is of central importance for tissue diagnosis and image guidance for surgery. Thepotential applications of the Mueller polarimetric endoscope include wide field early epithelial cancerdiagnosis, surgical margin detection and energy-based tissue fusion monitoring, and could furtherbenefit a wide range of endoscopic investigations through intra-operative guidance.
Elson DS, 2016, Surgical endoscopy, vision and bio-photonics, Royal Society International Scientific Seminar: Imaging in Graphics, Vision and Beyond
Wirkert SJ, Kenngott H, Mayer B, et al., 2016, Robust near real-time estimation of physiological parameters from megapixel multispectral images with inverse Monte Carlo and random forest regression, International Journal of Computer Assisted Radiology and Surgery, Vol: 11, Pages: 909-917, ISSN: 1861-6410
PURPOSE: Multispectral imaging can provide reflectance measurements at multiple spectral bands for each image pixel. These measurements can be used for estimation of important physiological parameters, such as oxygenation, which can provide indicators for the success of surgical treatment or the presence of abnormal tissue. The goal of this work was to develop a method to estimate physiological parameters in an accurate and rapid manner suited for modern high-resolution laparoscopic images. METHODS: While previous methods for oxygenation estimation are based on either simple linear methods or complex model-based approaches exclusively suited for off-line processing, we propose a new approach that combines the high accuracy of model-based approaches with the speed and robustness of modern machine learning methods. Our concept is based on training random forest regressors using reflectance spectra generated with Monte Carlo simulations. RESULTS: According to extensive in silico and in vivo experiments, the method features higher accuracy and robustness than state-of-the-art online methods and is orders of magnitude faster than other nonlinear regression based methods. CONCLUSION: Our current implementation allows for near real-time oxygenation estimation from megapixel multispectral images and is thus well suited for online tissue analysis.
Clancy NT, Teare J, Hanna GB, et al., 2016, Flexible Multimode Endoscope for Tissue Reflectance and Autofluorescence Hyperspectral Imaging, OSA Topical Meetings, Biomedical Optics
Elson DS, 2016, Application of Targeted Fluorescent Gold Nanorods for Image Guided Cancer Thermal Therapy (invited), OSA Topical Meetings, Biomedical Optics
Zhang Y, Wirkert SJ, Iszatt J, et al., 2016, Tissue classification for laparoscopic image understanding based on multispectral texture analysis, Conference on SPIE Image-Guided Procedures, Robotic Interventions, and Modeling, Publisher: Society of Photo-optical Instrumentation Engineers (SPIE), ISSN: 1996-756X
Intra-operative tissue classification is one of the prerequisites for providing context-aware visualization in computer-assisted minimally invasive surgeries. As many anatomical structures are difficult to differentiate in conventional RGB medical images, we propose a classification method based on multispectral image patches. In a comprehensive ex vivo study we show (1) that multispectral imaging data is superior to RGB data for organ tissue classification when used in conjunction with widely applied feature descriptors and (2) that combining the tissue texture with the reflectance spectrum improves the classification performance. Multispectral tissue analysis could thus evolve as a key enabling technique in computer-assisted laparoscopy.
Elson DS, Singh M, Nabavi E, et al., 2016, Application of Gold Nanorods in Cancer Theranostics, Association of Surgeons in Training
Thompson AJ, Koziej L, Williams H, et al., 2016, Towards optical fibre based Raman spectroscopy for the detection of surgical site infection, BiOS, SPIE Photonics West, Publisher: SPIE
Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Singh M, Harris-Birtill DCC, Zhou Y, et al., 2016, Application of Gold Nanorods for Photothermal Therapy in Ex Vivo Human Oesophagogastric Adenocarcinoma, Journal of Biomedical Nanotechnology, Vol: 12, Pages: 481-490, ISSN: 1550-7041
Gold nanoparticles are chemically fabricated and tuned to strongly absorb near infrared (NIR) light, enabling deep optical penetration and therapy within human tissues, where sufficient heating induces tumour necrosis. In our studies we aim to establish the optimal gold nanorod (GNR) concentration and laser power for inducing hyperthermic effects in tissues and test this photothermal effect on ex vivo human oesophagogastric adenocarcinoma. The ideal GNR concentration and NIR laser power that would elicit sufficient hyperthermia for tumour necrosis was pre-determined on porcine oesophageal tissues. Human ex vivo oesophageal and gastric adenocarcinoma tissues were incubated with GNR solutions and a GNR-free control solution with corresponding healthy tissues for comparison, then irradiated with NIR light for 10 minutes. Temperature rise was found to vary linearly with both the concentration of GNRs and the laser power. Human ex vivo oesophageal and gastric tissues consistently demonstrated a significant temperature rise when incubated in an optimally concentrated GNR solution (3 × 1010 GNRs/ml) prior to NIR irradiation delivered at an optimal power (2 W/cm2). A mean temperature rise of 27 °C was observed in tissues incubated with GNRs, whereas only a modest 2 °C rise in tissues not exposed to any GNRs. This study evaluates the photothermal effects of GNRs on oesophagogastric tissue examines their application in the minimally invasive therapeutics of oesophageal and gastric adenocarcinomas. This could potentially be an effective method of clinically inducing irreversible oesophagogastric tumour photodestruction, with minimal collateral damage expected in (healthy) tissues free from GNRs.
Nabavi E, Singh M, Zhou Y, et al., 2016, Preliminary studies of fluorescence image-guided photothermal therapy of human oesophageal adenocarcinoma in vivo using multifunctional gold nanorods, Conference on Optical Methods for Tumor Treatment and Detection - Mechanisms and Techniques in Photodynamic Therapy XXV, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
We present a preliminary in vivo study of fluorescence imaging and photothermal therapy (PTT) of human oesophageal adenocarcinoma using multi-functionalised gold nanorods (GNRs). After establishing tumour xenograft in mouse functionalised GNRs were administrated intravenously (IV). Fluorescence imaging was performed to detect the tumour area. The intensity of the fluorescence signal varied significantly across the tumour site and surrounding tissues. PTT was then performed using a 808 nm continuous wave diode laser to irradiate the tumour for 3 minutes, inducing a temperature rise of ~44°C, which photothermally ablated the tumour.
Song L, Zhou Z, Wang X, et al., 2016, Simulation of speckle patterns with pre-defined correlation distributions, Biomedical Optics Express, Vol: 7, Pages: 798-809, ISSN: 2156-7085
We put forward a method to easily generate a single or a sequence of fully developed speckle patterns with pre-defined correlation distribution by utilizing the principle of coherent imaging. The few-to-one mapping between the input correlation matrix and the correlation distribution between simulated speckle patterns is realized and there is a simple square relationship between the values of these two correlation coefficient sets. This method is demonstrated both theoretically and experimentally. The square relationship enables easy conversion from any desired correlation distribution. Since the input correlation distribution can be defined by a digital matrix or a gray-scale image acquired experimentally, this method provides a convenient way to simulate real speckle-related experiments and to evaluate data processing techniques.
Qi J, Elson DS, 2016, A high definition Mueller polarimetric endoscope for tissue characterisation, BIOS - Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XIV
Lin JIANYU, Clancy NT, Sun X, et al., 2016, Probe-based Rapid Hybrid Hyperspectral and Tissue Surface Imaging Aided by Fully Convolutional Networks, Medical Image Computing and Computer Assisted Intervention (MICCAI)
Qi J, Elson D, 2016, Polarimetric rigid endoscopes for tissue imaging, 2nd Workshop of the European Industrial Doctorate
Qi J, Elson D, 2016, A high definition Mueller polarimetric endoscope for tissue characterisation, BIOS - Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XIV
Singh M, Nabavi E, Zhou Y, et al., 2016, Application of Gold Nanorods in Cancer Theranostics, European Association for Endoscopic Surgery (EAES)
Singh M, Navabi E, Zhou Y, et al., 2016, Application of Gold Nanorods in Cancer Theranostics (winner SARS/ASiT Prize), Association of Surgeons in Training
Lin J, Clancy NT, Sun X, et al., 2016, Hybrid Tissue Surface Hyperspectral imaging and Shape Recovery, Hyperspectral Imaging & Applications Conference
Singh M, Nabavi E, Zhou Y, et al., 2016, Application of Gold Nanoparticles for Photothermal Therapy of Upper Gastrointestinal Adenocarcinoma, Bio-Nano-Photonics Symposium
Gallina ME, Zhou Y, Johnson CJ, et al., 2015, Aptamer-conjugated, fluorescent gold nanorods as potential cancer theradiagnostic agents, Materials Science & Engineering C - Biomimetic and Supramolecular Systems, Vol: 59, Pages: 324-332, ISSN: 0928-4931
GNRs are emerging as a new class of probes for theradiagnostic applications thanks to their unique optical properties. However, the achievement of proper nanoconstructs requires the synthesis of highly pure GNRs with well-defined aspect ratio (AR), in addition to extensive surface chemistry modification to provide them with active targeting and, possibly, multifunctionality.In this work, we refined the method of the seed mediated growth and developed a robust procedure for the fabrication of GNRs with specific AR. We also revealed and characterized unexplored aging phenomena that follow the synthesis and consistently alter GNRs' final AR. Such advances appreciably improved the feasibility of GNRs fabrication and offered useful insights on the growth mechanism.We next produced fluorescent, biocompatible, aptamer-conjugated GNRs by performing ligand exchange followed by bioconjugation to anti-cancer oligonucleotide AS1411. In vitro studies showed that our nanoconstructs selectively target cancer cells while showing negligible cytotoxicity. As a result, our aptamer-conjugated GNRs constitute ideal cancer-selective multifunctional probes and promising candidates as photothermal therapy agents.
Clancy NT, Arya S, Stoyanov D, et al., 2015, Intraoperative measurement of bowel oxygen saturation using a multispectral imaging laparoscope, Biomedical Optics Express, Vol: 6, Pages: 4179-4190, ISSN: 2156-7085
Intraoperative monitoring of tissue oxygen saturation (StO2) has potentially important applications in procedures such as organ transplantation or colorectal surgery, where successful reperfusion affects the viability and integrity of repaired tissues. In this paper a liquid crystal tuneable filter-based multispectral imaging (MSI) laparoscope is described. Motion-induced image misalignments are reduced, using feature-based registration, before regression of the tissue reflectance spectra to calculate relative quantities of oxy- and deoxyhaemoglobin. The laparoscope was validated in vivo, during porcine abdominal surgery, by making parallel MSI and blood gas measurements of the small bowel vasculature. Ischaemic conditions were induced by local occlusion of the mesenteric arcade and monitored using the system. The MSI laparoscope was capable of measuring StO2 over a wide range (30-100%) with a temporal error of ± 7.5%. The imager showed sensitivity to spatial changes in StO2 during dynamic local occlusions, as well as tracking the recovery of tissues post-occlusion.
Elson DS, 2015, Surgical Imaging, Biophotonics and Endoscopy (invited), Optoelectronic Global Conference 2015
Lin J, Clancy NT, Elson DS, 2015, An endoscopic structured light system using multispectral detection., International Journal of Computer Assisted Radiology and Surgery, Vol: 10, Pages: 1941-1950, ISSN: 1861-6410
PURPOSE: In clinical examinations, the tissue surface topology is an important feature for detecting the tissue pathology and implementing augmented reality. We have previously presented a miniaturised structured light (SL) system for recovery of tissue surface shape in minimally invasive surgery (MIS), based on a flexible multispectral structured illumination probe (1.9 mm diameter) (Clancy et al. in Biomed Opt Express 2(11):3119-3128, 2011. doi: 10.1364/BOE.2.003119 ). This paper reports further hardware and analytical developments to improve the light pattern decoding result and increase the reconstruction accuracy. METHODS: The feasibility of using an 8-band multispectral camera with higher pattern-colour discrimination ability than normal RGB camera in this system was studied. Additionally, the "normalised cut" algorithm was investigated to improve pattern segmentation. RESULTS: The whole SL system was evaluated by phantom and in vivo experiments. Higher pattern identification performance than that of an RGB camera was recorded by using the multispectral camera (average precision >97 %, average sensitivity >62 %). An average of [Formula: see text] reconstruction error was achieved using the proposed pattern decoding method on a heart phantom at a working distance of approximately 10 cm. CONCLUSIONS: The experiment showed the superiority of the multispectral camera over the RGB camera in the spot identification step. The proposed pattern decoding algorithm underwent evaluations using different experiments, showing that it provided promising reconstruction results. The potential of using this system in MIS environments has been demonstrated.
Clancy NT, Arya S, Stoyanov D, et al., 2015, Imaging the spectral reflectance properties of bipolar radiofrequency-fused bowel tissue, Conference on Clinical and Biomedical Spectroscopy and Imaging IV held at the European Conferences on Biomedical Optics, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, Pages: 953717-1-953717-6, ISSN: 0277-786X
Delivery of radiofrequency (RF) electrical energy is used during surgery to heat and seal tissue, such as vessels, allowing resection without blood loss. Recent work has suggested that this approach may be extended to allow surgical attachment of larger tissue segments for applications such as bowel anastomosis.In a large series of porcine surgical procedures bipolar RF energy was used to resect and re-seal the small bowel in vivo with a commercial tissue fusion device (Ligasure; Covidien PLC, USA). The tissue was then imaged with a multispectral imaging laparoscope to obtain a spectral datacube comprising both fused and healthy tissue. Maps of blood volume, oxygen saturation and scattering power were derived from the measured reflectance spectra using an optimised light-tissue interaction model.A 60% increase in reflectance of visible light (460-700 nm) was observed after fusion, with the tissue taking on a white appearance. Despite this the distinctive shape of the haemoglobin absorption spectrum was still noticeable in the 460-600 nm wavelength range. Scattering power increased in the fused region in comparison to normal serosa, while blood volume and oxygen saturation decreased.Observed fusion-induced changes in the reflectance spectrum are consistent with the biophysical changes induced through tissue denaturation and increased collagen cross-linking. The multispectral imager allows mapping of the spatial extent of these changes and classification of the zone of damaged tissue. Further analysis of the spectral data in parallel with histopathological examination of excised specimens will allow correlation of the optical property changes with microscopic alterations in tissue structure. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Du X, Clancy N, Arya S, et al., 2015, Robust surface tracking combining features, intensity and illumination compensation, International Journal of Computer Assisted Radiology and Surgery, Vol: 10, Pages: 1915-1926, ISSN: 1861-6410
Purpose Recovering tissue deformation during robotic-assisted minimally invasivesurgery (MIS) procedures is important for providing intra-operative guidance,enabling in vivo imaging modalities and enhanced robotic control. The tissue motioncan also be used to apply motion stabilization and to prescribe dynamicconstraints for avoiding critical anatomical structures.Methods Image-based methods based independently on salient features or onimage intensity have limitations when dealing with homogeneous soft-tissues orcomplex reflectance. In this paper, we use a triangular geometric mesh model inorder to combine the advantages of both feature and intensity information andtrack the tissue surface reliably and robustly.Results Synthetic and in vivo experiments are performed to provide quantitativeanalysis of the tracking accuracy of our method, we also show exemplar results forregistering multispectral images where there is only a weak image signal.Conclusions Compared to traditional methods, our hybrid tracking method ismore robust and has improved convergence in the presence of larger displacements,tissue dynamics and illumination changes.
Singh M, Harris-Birtill DCC, Markar SR, et al., 2015, Application of Gold Nanoparticles for Gastrointestinal Cancer Theranostics: A Systematic Review., Nanomedicine: Nanotechnology, Biology, and Medicine, Vol: 11, Pages: 2083-2098, ISSN: 1549-9634
Gold nanoparticles (GNPs) are readily synthesised structures that absorb light strongly to generate thermal energy which induces photothermal destruction of malignant tissue. This review examines the efficacy, potential challenges and toxicity from in vitro and in vivo applications of GNPs in oesophageal, gastric and colon cancers. A systematic literature search of Medline, Embase, Web of Science and Cochrane databases was performed using PRISMA guidelines. Two hundred and eighty-four papers were reviewed with sixteen studies meeting the inclusion criteria. The application of GNPs in eleven in vivo rodent studies with GI adenocarcinoma demonstrated excellent therapeutic outcomes but poor corroboration in terms of the cancer cells used, photothermal irradiation regimes, fluorophores and types of nanoparticles. There is compelling evidence of the translational potential of GNPs to be complimentary to surgery and feasible in the photothermal therapy of GI cancer but reproducibility and standardisation require further development prior to GI cancer clinical trials.
Singh M, Nabavi E, Zhou Y, et al., 2015, APPLICATION OF GOLD NANORODS FOR IN VIVO THERANOSTICS OF HUMAN OESOPHAGEAL ADENOCARCINOMA, 2nd Digestive-Disorders-Federation Conference, Publisher: BMJ PUBLISHING GROUP, Pages: A471-A471, ISSN: 0017-5749
Thum MY, Saso S, Clancy N, et al., 2015, Imaging of organ viability during uterine transplantation surgery, 31st Annual Meeting of the European-Society-of-Human-Reproduction-and-Embryology (ESHRE), Publisher: OXFORD UNIV PRESS, Pages: 34-34, ISSN: 0268-1161
Li S, Cheng Y, Eckersley RJ, et al., 2015, Dual shear wave induced laser speckle contrast signal and the improvement in shear wave speed measurement, Biomedical Optics Express, Vol: 6, Pages: 1954-1962, ISSN: 2156-7085
Shear wave speed is quantitatively related to tissue viscoelasticity.Previously we reported shear wave tracking at centimetre depths ina turbid optical medium using laser speckle contrast detection. Shear waveprogression modulates displacement of optical scatterers and therefore modulatesphoton phase and changes the laser speckle patterns. Time-resolvedcharge-coupled device (CCD)-based speckle contrast analysis was used totrack shear waves and measure the time-of-flight of shear waves for speedmeasurement. In this manuscript, we report a new observation of the laserspeckle contrast difference signal for dual shear waves. A modulation ofCCD speckle contrast difference was observed and simulation reproducesthe modulation pattern, suggesting its origin. Both experimental andsimulation results show that the dual shear wave approach generates animproved definition of temporal features in the time-of-flight optical signaland an improved signal to noise ratio with a standard deviation less than50% that of individual shear waves. Results also show that dual shear wavescan correct the bias of shear wave speed measurement caused by shear wavereflections from elastic boundaries.
Williams P, Arya S, Wei R, et al., 2015, Radiofrequency induced small bowel thermofusion: a study of serosa-to-serosa seal adequacy using mechanical and imaging modalities, Annual Meeting of the Society-of-Academic-and-Research-Surgery (SARS(, Publisher: WILEY-BLACKWELL, Pages: 33-33, ISSN: 0007-1323
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