Publications
52 results found
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: 2329-4310
Intraoperative 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 through statistical analysis, we show that (1) multispectral imaging data are superior to RGB data for organ tissue classification when used in conjunction with widely applied feature descriptors and (2) combining the tissue texture with the reflectance spectrum improves the classification performance. The classifier reaches an accuracy of 98.4% on our dataset. Multispectral tissue analysis could thus evolve as a key enabling technique in computer-assisted laparoscopy.
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
Uterine transplantation surgery (UTx) has been proposed as a treatment for permanent absolute uterine factor infertility (AUFI) in the case of the congenital absence or surgical removal of the uterus. Successful surgical attachment of the organ and its associated vasculature is essential for the organ’s reperfusion and long-term viability. Spectral imaging techniques have demonstrated the potential for the measurement of hemodynamics in medical applications. These involve the measurement of reflectance spectra by acquiring images of the tissue in different wavebands. Measures of tissue constituents at each pixel can then be extracted from these spectra through modeling of the light–tissue interaction. A multispectral imaging (MSI) laparoscope was used in sheep and rabbit UTx models to study short- and long-term changes in oxygen saturation following surgery. The whole organ was imaged in the donor and recipient animals in parallel with point measurements from a pulse oximeter. Imaging results confirmed the re-establishment of adequate perfusion in the transplanted organ after surgery. Cornual oxygenation trends measured with MSI are consistent with pulse oximeter readings, showing decreased StO2 immediately after anastomosis of the blood vessels. Long-term results show recovery of StO2 to preoperative levels.
Lin J, Clancy NT, Sun X, et al., 2016, Hybrid Tissue Surface Hyperspectral imaging and Shape Recovery, Hyperspectral Imaging & Applications Conference
Lin J, 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)
Jones G, Clancy NT, Arridge S, et al., 2016, Inference of Tissue Haemoglobin Concentration From Stereo RGB, 7th International Conference on Medical Imaging and Augmented Reality
Wirkert S, 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, Information Processing in Comupter Aided Intervention
Saso S, Jones B, Clancy N, et al., 2016, Imaging of organ viability during deep pelvic surgery: The use of biomedical photonics to assess uterine perfusion and vessel integrity in uterine transplantation models, Publisher: Wiley, Pages: 20-20, ISSN: 1471-0528
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, Optical Tomography and Spectroscopy 2016, Publisher: Optica Publishing Group
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.
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.
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.
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: Society of Photo-Optical Instrumentation Engineers (SPIE), 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.
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
Arya S, Chalau V, Singh M, et al., 2015, Bipolar radiofrequency energy as a novel method of bowel anastomosis: results of a comparative animal study, Annual Meeting of the Society-of-Academic-and-Research-Surgery (SARS(, Publisher: WILEY-BLACKWELL, Pages: 38-38, ISSN: 0007-1323
Qi J, Singh M, Pigula A, et al., 2015, Rigid endoscopic polarimetric wide-field imaging (invited), SPIE BiOS Molecular-Guided Surgery
Saso S, Clancy N, Jones B, et al., 2015, Assessing uterine graft viability using multispectral imaging during uterine transplantation, 25th World Congress on Ultrasound in Obstetrics and Gynecology
Saso S, Clancy N, Tziraki M, et al., 2015, Use of endoscopic laser speckle contrast analysis to assess uterine perfusion and blood flow in a uterine transplantation model, 25th World Congress on Ultrasound in Obstetrics and Gynecology
Lin J, Clancy NT, Elson DS, 2015, An endoscopic structured light system using multispectral detection, International Conference on Information Processing and Computer Assisted Interventions
Clancy NT, Lin J, Arya S, et al., 2015, Dual multispectral and 3D structured light laparoscope, Conference on Multimodal Biomedical Imaging X, Publisher: SPIE, ISSN: 0277-786X
Pigula A, Clancy NT, Arya S, et al., 2015, Video-rate dual polarization multispectral endoscopic imaging, Conference on Biomedical Applications of Light Scattering IX, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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- Citations: 2
Lin J, Clancy NT, Stoyanov D, et al., 2015, Tissue Surface Reconstruction Aided by Local Normal Information Using a Self-calibrated Endoscopic Structured Light System, 18th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: 405-412, ISSN: 0302-9743
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- Citations: 8
Clancy NT, Arya S, Qi J, et al., 2014, Polarised stereo endoscope and narrowband detection for minimal access surgery, BIOMEDICAL OPTICS EXPRESS, Vol: 5, Pages: 4108-4117, ISSN: 2156-7085
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- Citations: 32
Clancy NT, Corbett RW, Herbert PE, et al., 2014, Intraoperative Measurement of Vessel Wall Oxygenation During Formation of Native Arteriovenous Fistulae, American Society of Neprhology - Kidney Week, Publisher: American Society of Neprhology
Maier-Hein L, Groch A, Bartoli A, et al., 2014, Comparative validation of single-shot optical techniques for laparoscopic 3-D surface reconstruction, IEEE Transactions on Medical Imaging, Vol: 33, Pages: 1913-1930, ISSN: 0278-0062
Intra-operative imaging techniques for obtaining the shape and morphology of soft-tissue surfaces in vivo are a key enabling technology for advanced surgical systems. Different optical techniques for 3-D surface reconstruction in laparoscopy have been proposed, however, so far no quantitative and comparative validation has been performed. Furthermore, robustness of the methods to clinically important factors like smoke or bleeding has not yet been assessed. To address these issues, we have formed a joint international initiative with the aim of validating different state-of-the-art passive and active reconstruction methods in a comparative manner. In this comprehensive in vitro study, we investigated reconstruction accuracy using different organs with various shape and texture and also tested reconstruction robustness with respect to a number of factors like the pose of the endoscope as well as the amount of blood or smoke present in the scene. The study suggests complementary advantages of the different techniques with respect to accuracy, robustness, point density, hardware complexity and computation time. While reconstruction accuracy under ideal conditions was generally high, robustness is a remaining issue to be addressed. Future work should include sensor fusion and in vivo validation studies in a specific clinical context. To trigger further research in surface reconstruction, stereoscopic data of the study will be made publically available at www.open-CAS.com upon publication of the paper.
Wickert S, Clancy N T, Stoyanov D, et al., 2014, Endoscopic Sheffield Index for Unsupervised In Vivo Spectral Band Selection
Qi J, Singh M, Clancy N, et al., 2014, Mueller polarimetric endoscopy, CLEO: Applications and Technology, Publisher: Optical Society of America
Clancy NT, Saso S, Stoyanov D, et al., 2014, Multispectral Imaging of Organ Viability during Uterine Transplantation Surgery, Conference on Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XII, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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- Citations: 8
Qi J, Ye M, Singh M, et al., 2013, Narrow band 3 x 3 Mueller polarimetric endoscopy, BIOMEDICAL OPTICS EXPRESS, Vol: 4, Pages: 2433-2449, ISSN: 2156-7085
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- Citations: 61
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