Portrait of Dr Michael Hughes

Dr Michael Hughes

Lecturer in Applied Optics

About

Dr Michael Hughes is a lecturer in the School of Physical Sciences and a member of the Applied Optics Group, where he develops photonics techniques for applications in biosciences and medicine. His lab currently focuses on new ways of building thin, flexible endoscopic and needle microscopes – miniature probes that allow us to visualise living tissue in real time. Michael is also interested in developing novel, low-cost microscopes for point-of-care and low-resource imaging.

Michael began his career at Durham University, graduating in 2006 with an MSci in Physics. He moved south to Canterbury for his PhD to work on a joint project with the British Museum, the National Gallery and NTU, developing applications of optical coherence tomography (OCT) in art conservation and archaeology. Changing direction slightly, he moved to Oxford University Hospitals NHS Trust to complete the IPEM Part 1 training programme in medical physics, with rotations in diagnostic radiology, nuclear medicine and radiotherapy. 

Returning to the world of optics in late 2011, Michael took up the position of Research Associate in Biophotonics at the Hamlyn Centre, Imperial College London, where he developed endomicroscopy systems for applications in surgery, and later became a Hamlyn Fellow. He moved to the University of Kent as a lecturer in 2017 to develop a research programme in point-of-care and endoscopic microscopy.

Research interests

Dr Michael Hughes’s lab is focused on high resolution, in-vivo optical imaging (optical biopsy), a technique that allows the imaging of human tissue at a cellular level in real time. This relies on miniaturised microscope probes, built using fibre optic technology, which are small and flexible enough to be passed along the instrument channel of an endoscope, or to be introduced via a needle. These probes can then be used to display a live microscope video-feed to the operator.

Optical biopsy is an alternative to the conventional approach to high resolution tissue imaging (histology), where small amounts of tissue are extracted from the patient during a biopsy procedure and sent to a laboratory to be viewed under a bench-top microscope. The advantage of endomicroscopy is that, instead of waiting hours or days for a report from the histopathology lab, clinicians can see the results immediately.

While at Imperial College, Michael worked as part of a team on an EPSRC-funded project developing new endomicroscopy technology to aid more widespread clinical adoption. In particular, they worked on methods for improving the image resolution and field of view, enabling them to characterise larger areas of tissue. He developed high frame rate endomicroscopes (120 fps) which offer depth sectioning using the line scanning technique, allowing better assembly of mosaics (ie the stitching  together of images) even when the endomicroscope probe is moved rapidly across the tissue. The team also showed that they could enhance the optical sectioning to near that of a point-scanning confocal endomicroscope using a two-step technique. 

Michael also developed white light endomicroscopes, as well as working with colleagues, particularly Siyang Zuo, Petros Giataganas, Lin Zhang, and Chris Payne to integrate robotics and other smart technology with endomicroscopy imaging probes. They particularly focused on applications in breast-conserving surgery, with a recent study led by Khushi Vyas and an older study led by Tou Pin Chang clearly demonstrating the potential. Michael has also worked on a horizon scan funded by the Bill and Melinda Gates Foundation, looking at the potential role of optical biopsy techniques for gut disease in the developing world.

At Kent, Michael holds an EPSRC grant to develop an ‘ultrathin fluorescence microscope in a needle’, using a technique known as ‘ghost imaging’ or ‘single pixel imaging’. Members of his lab are also exploring other avenues, including techniques for low-cost optical sectioning in fibre bundle endomicroscopy, as well as the integration of endomicroscopy with other optical biopsy techniques. 

Michael works on another EPSRC project, ‘REBOT – Robotic Endobronchial Optical Tomography‘, a collaboration with Imperial College London where he was originally researcher co-investigator. In this project they are developing a robotic catheter equipped with multi-modal imaging systems for investigations in the lung.

Teaching

Michael is involved with teaching in the areas of astronomy and special relativity, electricity and light, and biomedical optics.  

Supervision

Dr Hughes is always happy to speak with potential MSc and PhD candidates (for degrees in Physics) about self-funded study or applying for external funding. Funded positions are advertised when available. 

Dr Hughes is also able to host a small number of undergraduate students in the lab over the summer vacation; please contact him well in advance to discuss. 

Professional


Publications

Article

  • Vyas, K. et al. (2018). Fiber bundle shifting endomicroscopy for high-resolution imaging. Biomedical Optics Express [Online] 9:4649. Available at: https://doi.org/10.1364/BOE.9.004649.
    Flexible endomicroscopes commonly use coherent fiber bundles with high core densities to facilitate high-resolution in vivo imaging during endoscopic and minimally-invasive procedures. However, under-sampling due to the inter-core spacing limits the spatial resolution, making it difficult to resolve smaller cellular features. Here, we report a compact and rapid piezoelectric transducer (PZT) based bundle-shifting endomicroscopy system in which a super-resolution (SR) image is restored from multiple pixelation-limited images by computational means. A miniaturized PZT tube actuates the fiber bundle behind a GRIN micro-lens and a Delaunay triangulation based algorithm reconstructs an enhanced SR image. To enable real-time cellular-level imaging, imaging is performed using a line-scan confocal laser endomicroscope system with a raw frame rate of 120 fps, delivering up to 2 times spatial resolution improvement for a field of view of 350 µm at a net frame rate of 30 fps. The resolution enhancement is confirmed using resolution phantoms and ex vivo fluorescence endomicroscopy imaging of human breast specimens is demonstrated.
  • Giataganas, P. et al. (2018). Intraoperative robotic-assisted large-area high-speed microscopic imaging and intervention. IEEE Transactions on Biomedical Engineering [Online]. Available at: https://doi.org/10.1109/TBME.2018.2837058.
    Objective: Probe-based confocal endomicroscopy is an emerging high-magnification optical imaging technique that provides in-vivo and in-situ cellular-level imaging for real-time assessment of tissue pathology. Endomicroscopy could potentially be used for intraoperative surgical guidance, but it is challenging to assess a surgical site using individual microscopic images due to the limited field-of-view and difficulties associated with manually manipulating the probe. Methods: In this paper, a novel robotic device for large-area endomicroscopy imaging is proposed, demonstrating a rapid, but highly accurate, scanning mechanism with image-based motion control which is able to generate histology-like endomicroscopy mosaics. The device also includes, for the first time in robotic-assisted endomicroscopy, the capability to ablate tissue without the need for an additional tool. Results: The device achieves pre-programmed trajectories with positioning accuracy of less than 30um, the image-based approach demonstrated that it can suppress random motion disturbances up to 1.25mm/s. Mosaics are presented from a range of ex-vivo human and animal tissues, over areas of more than 3mm², scanned in approximate 10s. Conclusion: This work demonstrates the potential of the proposed instrument to generate large-area, high-resolution microscopic images for intraoperative tissue identification and margin assessment. Significance: This approach presents an important alternative to current histology techniques, significantly reducing the tissue assessment time, while simultaneously providing the capability to mark and ablate suspicious areas intraoperatively.
  • Zhang, L. et al. (2017). From Macro to Micro: Autonomous Multiscale Image Fusion for Robotic Surgery. IEEE Robotics & Automation Magazine [Online] PP:1-1. Available at: https://doi.org/10.1109/MRA.2017.2680543.
  • Thompson, A. et al. (2017). Position paper: The potential role of optical biopsy in the study and diagnosis of environmental enteric dysfunction. Nature Reviews Gastroenterology & Hepatology [Online]. Available at: https://doi.org/10.1038/nrgastro.2017.147.
    Environmental enteric dysfunction (EED) is a disease of the small intestine affecting children and adults in low and middle income countries. Arising as a consequence of repeated infections, gut inflammation results in impaired intestinal absorptive and barrier function, leading to poor nutrient uptake and ultimately to stunting and other developmental limitations. Progress towards new biomarkers and interventions for EED is hampered by the practical and ethical difficulties of cross-validation with the gold standard of biopsy and histology. Optical biopsy techniques — which can provide minimally invasive or noninvasive alternatives to biopsy — could offer other routes to validation and could potentially be used as point-of-care tests among the general population. This Consensus Statement identifies and reviews the most promising candidate optical biopsy technologies for applications in EED, critically assesses them against criteria identified for successful deployment in developing world settings, and proposes further lines of enquiry. Importantly, many of the techniques discussed could also be adapted to monitor the impaired intestinal barrier in other settings such as IBD, autoimmune enteropathies, coeliac disease, graft-versus-host disease, small intestinal transplantation or critical care.
  • Vyas, K. et al. (2017). Methylene-blue aided rapid confocal laser endomicroscopy of breast cancer. Journal of Biomedical Optics [Online] 22:20501. Available at: https://doi.org/10.1117/1.JBO.22.2.020501.
    Breast conserving surgery allows complete tumor resection while maintaining acceptable cosmesis for patients. Safe and rapid intraoperative margin assessment during the procedure is important to establish the completeness of tumor excision and minimizes the need for reoperation. Confocal laser endomicroscopy has demonstrated promise for real-time intraoperative margin assessment using acriflavine staining, but it is not approved for routine in-human use. We describe a custom high-speed line-scan confocal laser endomicroscopy (LS-CLE) system at 660 nm that enables high-resolution histomorphological imaging of breast tissue stained with methylene-blue, an alternative fluorescent stain for localizing sentinel nodes during breast surgery. Preliminary imaging results on freshly excised human breast tissue specimens are presented, demonstrating the potential of methylene-blue aided rapid LS-CLE to determine the oncological status of surgical margins in-vivo.
  • Zuo, S., Hughes, M. and Yang, G. (2017). Flexible Robotic Scanning Device for Intraoperative Endomicroscopy in MIS. IEEE/ASME Transactions on Mechatronics [Online] PP:1-1. Available at: https://doi.org/10.1109/TMECH.2017.2700008.
    Optical biopsy methods such as probe-based confocal endomicroscopy can provide intraoperative real-time assessment of tumour margins, including during minimally invasive surgery with flexible endoscopes or robotic platforms. Mosaics can be produced by translating the probe across the target, but it remains difficult to scan over a large field-of-view with a flexible endomicroscope. In this paper, we have developed a novel flexible scanning device for intraoperative endomicroscopy in MIS. A Schott leached imaging bundle was integrated into the device and enables the approach, via a flexible path, to deep and narrow spaces in the human body that otherwise would not accessible. The proposed device uses a gear-based flexible concentric tube scanning mechanism to facilitate large field-of-view mosaicing. Experimental results show that the device is able to scan different surface trajectories (e.g. a spiral pattern over a hemi-spherical surface). Results from lens tissue paper and porcine liver tissue are demonstrated, illustrating a viable scanning approach for endomicroscopy in MIS.
  • Hughes, M. and Yang, G. (2016). Line-scanning fiber bundle endomicroscopy with a virtual detector slit. Biomedical Optics Express [Online] 7:2257-2268. Available at: https://doi.org/10.1364/BOE.7.002257.
    Coherent fiber bundles can be used to relay the image plane from the distal tip of an endomicroscope to an external confocal microscopy system. The frame rate is therefore determined by the speed of the microscope’s laser scanning system which, at 10-20 Hz, may be undesirably low for in vivo clinical applications. Line-scanning allows an increase in the frame rate by an order of magnitude in exchange for some loss of optical sectioning, but the width of the detector slit cannot easily be adapted to suit different imaging conditions. The rolling shutter of a CMOS camera can be used as a virtual detector slit for a bench-top line-scanning confocal microscope, and here we extend this idea to endomicroscopy. By synchronizing the camera rolling shutter with a scanning laser line we achieve confocal imaging with an electronically variable detector slit. This architecture allows us to acquire every other frame with the detector slit offset by a known distance, and we show that subtracting this second image leads to improved optical sectioning.
  • Zuo, S. et al. (2015). Toward Intraoperative Breast Endomicroscopy With a Novel Surface-Scanning Device. IEEE Transactions on Biomedical Engineering [Online] 62:2941-2952. Available at: https://doi.org/10.1109/TBME.2015.2455597.
    New optical biopsy methods such as confocal endomicroscopy represent a promising tool for breast conserving surgery, allowing real-time assessment of tumor margins. However, it remains difficult to scan over a large surface area because of the small field-of-view. This paper presents a novel robotic instrument to perform automated scanning with a fiber bundle endomicroscope probe to expand the effective imaging area. The device uses a rigid concentric tube scanning mechanism to facilitate large-area mosaicking. It has a compact design with a diameter of 6 mm, incorporating a central channel with a diameter of 3 mm for passing through a fiber bundle probe. A bespoke bearing, an inflated balloon, and a passive linear structure are used to control image rotation and ensure consistent tool-tissue contact. Experimental results show that the device is able to scan a spiral trajectory over a large hemispherical surface. Detailed performance evaluation was performed and the bending angle ranges from -90° to 90° with high repeatability and minimal rotational hysteresis errors. The device has also been validated with breast phantom and ex vivo human breast tissue, demonstrating the potential clinical value of the system.
  • Chang, T. et al. (2015). Imaging breast cancer morphology using probe-based confocal laser endomicroscopy: towards a real-time intraoperative imaging tool for cavity scanning. Breast Cancer Research and Treatment [Online] 153:299-310. Available at: https://doi.org/10.1007/s10549-015-3543-8.
    Current techniques for assessing the adequacy of tumour excision during breast conserving surgery do not provide real-time direct cytopathological assessment of the internal cavity walls within the breast. This study investigates the ability of probe-based confocal laser endomicroscopy (pCLE), an emerging imaging tool, to image the morphology of neoplastic and non-neoplastic breast tissues, and determines the ability of histopathologists and surgeons to differentiate these images. Freshly excised tumour samples and adjacent non-diseased sections from 50 consenting patients were stained with 0.01 % acriflavine hydrochloride and imaged using pCLE. All discernible pCLE features were cross-examined with conventional histopathology. Following pattern recognition training, 17 histopathologists and surgeons with no pCLE experience interpreted 50 pCLE images independently whilst blinded to histopathology results. Three-hundred and fifty pCLE image mosaics were analysed. Consistent with histopathology findings, the glandular structures, adipocytes and collagen fibres of normal breast were readily visible on pCLE images. These were distinguishable from the morphological architecture exhibited by invasive and non-invasive carcinoma. The mean accuracy of pCLE image interpretation for histopathologists and surgeons was 94 and 92 %, respectively. Overall, inter-observer agreement for histopathologists was ‘almost perfect’, ? = 0.82; and ‘substantial’ for surgeons, ? = 0.74. pCLE morphological features of neoplastic and non-neoplastic breast tissues are readily visualized and distinguishable with high accuracy by both histopathologists and surgeons. Further research is required to investigate a potential role for the use of pCLE intraoperatively for in situ detection of residual cancerous foci, thereby guiding operating decision-making based on real-time breast cavity scanning.
  • Giataganas, P., Hughes, M. and Yang, G. (2015). Force adaptive robotically assisted endomicroscopy for intraoperative tumour identification. International Journal of Computer Assisted Radiology and Surgery [Online] 10:825-832. Available at: https://doi.org/10.1007/s11548-015-1179-0.
  • Hughes, M. and Yang, G. (2015). High speed, line-scanning, fiber bundle fluorescence confocal endomicroscopy for improved mosaicking. Biomedical Optics Express [Online] 6:1241-1252. Available at: https://doi.org/10.1364/BOE.6.001241.
    A significant limitation of fiber bundle endomicroscopy systems is that the field of view tends to be small, usually only several hundred micrometers in diameter. Image mosaicking techniques can increase the effective image size, but require careful manipulation of the probe to ensure sufficient overlap between adjacent frames. For confocal endomicroscopes, which typically have frame rates on the order of 10 fps, this is particularly challenging. In this paper we demonstrate that line-scanning confocal endomicroscopy can, by use of a high speed linear CCD camera, achieve a frame rate of 120 fps while maintaining sufficient resolution and signal-to-noise ratio to allow imaging of topically stained gastrointestinal tissues. This leads to improved performance of a cross-correlation based mosaicking algorithm when compared with lower frame-rate systems.
  • Zuo, S., Hughes, M. and Yang, G. (2015). Novel Balloon Surface Scanning Device for Intraoperative Breast Endomicroscopy. Annals of Biomedical Engineering [Online] 44:2313-2326. Available at: https://doi.org/10.1007/s10439-015-1493-2.
    Recent advances in fluorescence confocal endomicroscopy have allowed real-time identification of residual tumour cells on the walls of the cavity left by breast conserving surgery. However, it is difficult to systematically survey the surgical site because of the small imaging field-of-view of these probes, compounded by tissue deformation and inconsistent probe-tissue contact when operated manually. Therefore, a new robotized scanning device is required for controlled, large area scanning and mosaicing. This paper presents a robotic scanning probe with an inflatable balloon, providing stable cavity scanning over undulating surfaces. It has a compact design, with an outer diameter of 4 mm and a working channel of 2.2 mm, suitable for a leached flexible fibre bundle endomicroscope probe. With the probe inserted, the tip positioning accuracy measured to be 0.26 mm for bending and 0.17 mm for rotational motions. Large area scanning was achieved (25–35 mm2) and the experimental results demonstrate the potential clinical value of the device for intraoperative cavity tumour margin evaluation.
  • Hughes, M., Giataganas, P. and Yang, G. (2014). Color reflectance fiber bundle endomicroscopy without back-reflections. Journal of Biomedical Optics [Online] 19:30501. Available at: https://doi.org/10.1117/1.JBO.19.3.030501.
    Coherent fiber imaging bundles can be used as passive probes for reflectance-mode endomicroscopy providing that the back-reflections from the fiber ends are efficiently rejected. We describe an approach specific to widefield endomicroscopy in which light is injected into a leached fiber bundle near the distal end, thereby avoiding reflections from the proximal face. We use this method to demonstrate the color widefield reflectance endomicroscopy of ex vivo animal tissue.
  • Hughes, M., Chang, T. and Yang, G. (2013). Fiber bundle endocytoscopy. Biomedical Optics Express [Online] 4:2781. Available at: https://doi.org/10.1364/BOE.4.002781.
    Endocytoscopy is an optical biopsy technique which uses a miniaturized camera to capture white light microscopy images through an endoscope. We have developed an alternative design that instead relays images to an external camera via a coherent fiber bundle. In this paper we characterize the device and demonstrate microscopy of porcine tissue ex vivo. One advantage of our approach is the ease with which other bundle-compatible imaging modalities can be deployed simultaneously. We show this by acquiring quasi-simultaneous endocytoscopy and fluorescence confocal endomicroscopy images through a single fiber bundle. This opens up possibilities for multi-modal endomicroscopy, combining white light and fluorescence imaging.
  • Hughes, M., Spring, M. and Podoleanu, A. (2010). Speckle noise reduction in optical coherence tomography of paint layers. Applied Optics [Online] 49:99-107. Available at: http://dx.doi.org/10.1364/AO.49.000099.
    We present and characterize a sequential angular compounding method for reducing speckle contrast in optical coherence tomography images of paint layers. The results are compared with postprocessing methods, and we show that the compounding technique can improve the speckle contrast ratio in B-scans by better than a factor of 2 in exchange for a negligible loss of resolution. As a result, image aesthetics are improved, thin layers become more distinct, and edge-detection algorithms work more efficiently. The effect of varying the angular scan size and number of averages is investigated, and it is found that a degree of statistical correlation between speckle patterns exists, even for relatively large changes in angle of incidence. Angular compounding is also performed on three-dimensional data sets and compared with a method whereby en face slices are averaged over depth. © 2009 Optical Society of America.
  • Todea, C. et al. (2010). En face optical coherence tomography investigation of apical microleakage after laser-assisted endodontic treatment. Lasers in Medical Science [Online] 25:629-639. Available at: http://dx.doi.org/10.1007/s10103-009-0680-5.
    The aim of our study was to evaluate the potential of en face optical coherence tomography (OCT) for the detection of apical microleakage after 980 nm and 1,064 nm laser-assisted endodontic treatment. Ninety, human, single-rooted teeth with one straight root canal and closed apices were used. All roots were prepared biomechanically to the working length at an apical size 30 and 0.06 taper. The teeth were divided into three equal groups of 30 samples each, according to the treatment to be applied to the root canal. Group I received 980 nm diode laser (3 W, 0.01 s on time, 0.01 s off time, 5 s per procedure, four procedures); group II received neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1.5 W, 15 Hz, 5 s per procedure, four procedures). In group III the root canals were approached conventionally only. In all groups the root canal filling was performed with AH Plus endodontic sealer and gutta-percha points. An en face OCT prototype was used for the investigation of apical microleakage. According to one-way analysis of variance (ANOVA) and en face OCT, the number of defects in the laser groups was significantly lower (P<0.005) than in the control group. No statistical differences were noted between the laser groups (P=0.049). En face OCT imaging proved that laser-assisted endodontic treatment improved the prognosis of root canal filling and led to a reduction in apical microleakage. © 2009 Springer-Verlag London Ltd.
  • Hughes, M. and Podoleanu, A. (2009). Simplified dynamic focus method for time domain OCT. Electronics Letters [Online] 45:623-624. Available at: http://www.dx.doi.org/10.1049/el.2009.0672.
    A new optical arrangement for performing dynamic focus in time domain optical coherence tomography (OCT) is demonstrated. Unlike previously reported schemes which require mechanical coupling of the object and reference arms, this method is confined to the object arm only and therefore does not impose design constraints on the OCT system layout. The scheme is tested on a high lateral resolution OCT system (NA=0.13) and it is shown that the effective depth of focus is extended from 200m to better than 2mm. The optimum correction is for media with a mean refractive index of 1.4. © The Institution of Engineering and Technology 2009.
  • Hughes, M., Woods, D. and Podoleanu, A. (2009). Control of visibility profile in spectral low-coherence interferometry. Electronics Letters [Online] 45:182-183. Available at: http://dx.doi.org/10.1049/el:20092512.
    It is demonstrated that, by obstructing half of one of the two beams from a low coherence interferometer before it is incident on the diffraction grating in a spectral interferometry setup, an asymmetric profile can be generated for the visibility of the channelled spectrum (V) with optical path difference (OPD). Together with a lateral shift of the beam, as inspired by Talbot bands studies, this can be used to optimise V(OPD). The model for the visibility of Talbot bands is improved by considering the spectrometer resolution and an improved Talbot band experiment is demonstrated. It is also shown that it is possible to obtain regions of no interference around zero OPD.
  • Trifanov, I. et al. (2008). Quasi-simultaneous optical coherence tomography and confocal imaging. Journal of Biomedical Optics [Online] 13. Available at: http://dx.doi.org/10.1117/1.2957051.
    A new approach of acquiring quasi-simultaneous optical coherence tomography (OCT) and confocal images is presented. The two images are generated using different principles, OCT and confocal microscopy. When the system is used to image the retina, the two images have depth resolutions, at present, of <20 mu m and similar to 1 mm, respectively. The acquisition and display of en face OCT and confocal images are quasi-simultaneous, without the need of a beamsplitter. By using a chopper to periodically obstruct the reference beam in the OCT interferometer, synchronized with the XY-transversal scanner, much higher acquisition speed is obtained than in a previous report where we flipped an opaque screen in the reference arm of the interferometer. Successful operation of the novel configuration was achieved by: (1) stable synchronization of the chopper's movement with the horizontal line scanner and (2) fast self-adjusting of the gain value of avalanche photodiodes, depending on the optical power. Images from coin, leaves, and retina in vivo have been collected to demonstrate the functionality of the system. (C) 2008 Society of Photo-Optical Instrumentation Engineers.
  • Sinescu, C. et al. (2008). Quality assessment of dental treatments using en-face optical coherence tomography. Journal of Biomedical Optics [Online] 13. Available at: http://dx.doi.org/10.1117/1.2992593.
    The present study evaluates the potential of en-face optical coherence tomography (OCT) as a possible noninvasive high resolution method for supplying necessary information on the material defects of dental prostheses and microleakage at prosthetic interfaces. Teeth are also imaged after several treatment methods to asses material defects and microleakage at the tooth-filling interface, and the presence or absence of apical microleakage, as well as to evaluate the quality of bracket bonding on dental hard tissue. C-scan and B-scan OCT images as well as confocal images are acquired from a large range of samples. Gaps between the dental interfaces and material defects are clearly exposed.

Conference or workshop item

  • Zhang, L. et al. (2017). Autonomous scanning for endomicroscopic mosaicing and 3D fusion. in: IEEE International Conference on Robotics and Automation (ICRA). pp. 3587-3593. Available at: https://doi.org/10.1109/ICRA.2017.7989412.
    Robot-assisted minimally invasive surgery can benefit from the automation of common, repetitive or well-defined but ergonomically difficult tasks. One such task is the scanning of a pick-up endomicroscopy probe over a complex, undulating tissue surface to enhance the effective field-of-view through video mosaicing. In this paper, the da Vinci® surgical robot, through the dVRK framework, is used for autonomous scanning and 2D mosaicing over a user-defined region of interest. To achieve the level of precision required for high quality mosaic generation, which relies on sufficient overlap between consecutive image frames, visual servoing is performed using a combination of a tracking marker attached to the probe and the endomicroscopy images themselves. The resulting sub-millimetre accuracy of the probe motion allows for the generation of large mosaics with minimal intervention from the surgeon. Images are streamed from the endomicroscope and overlaid live onto the surgeons view, while 2D mosaics are generated in real-time, and fused into a 3D stereo reconstruction of the surgical scene, thus providing intuitive visualisation and fusion of the multi-scale images. The system therefore offers significant potential to enhance surgical procedures, by providing the operator with cellular-scale information over a larger area than could typically be achieved by manual scanning.
  • Dwyer, G. et al. (2015). A miniaturised robotic probe for real-time intraoperative fusion of ultrasound and endomicroscopy. in: 2015 IEEE International Conference on Robotics and Automation (ICRA). IEEE Press, pp. 1196-1201. Available at: https://doi.org/10.1109/ICRA.2015.7139343.
    Transanal Endoscopic Microsurgery (TEM) is a minimally invasive oncological resection procedure that utilises a natural orifice approach rather than the traditional abdominal or open approach. However, TEM has a significant recurrence rate due to incomplete excisions, which can possibly be attributed to the absence of intraoperative image guidance. The use of real-time histological data could allow the surgeons to assess the surgical margins intraoperatively and adjust the procedure accordingly. This paper presents the integration of endomicroscopy and ultrasound imaging through a robotically actuated instrument. Endomicroscopy can provide high resolution images at a surface level while ultrasound provides depth resolved information at a macroscopic level. Endomicroscopy scanning is achieved with a novel scanning approach featuring a passive force adaptive mechanism. The instrument is manipulated across the surgical workspace through an articulated flexible shaft. This results in the ability to perform large area mosaics coupled with ultrasound scanning. In addition, the use of endoscopic tracking is demonstrated, allowing three-dimensional reconstruction of the ultrasound data displayed onto the endoscopic view. An ex vivo study on porcine colon tissue has been performed, demonstrating the clinical applicability of the instrument.
  • Vyas, K., Hughes, M. and Yang, G. (2015). Electromagnetic tracking of handheld high-resolution endomicroscopy probes to assist with real-time video mosaicking. in: SPIE Endoscopic Microscopy X; and Optical Techniques in Pulmonary Medicine II,. Spie-Int Soc Optical Engineering, p. 93040Y. Available at: https://doi.org/10.1117/12.2085440.
    Optical fiber bundle based endomicroscopy is a low-cost optical biopsy technique for in vivo cellular level imaging. A limitation of such an imaging system, however, is its small field-of-view (FOV), typically less than 1 mm2. With such a small FOV it is difficult to associate individual image frames with the larger scale anatomical structure. Video-sequence mosaicking algorithms have been proposed as a solution for increasing the image FOV while maintaining cellular-level resolution by stitching together the endomicroscopy images. Although extensive research has focused on image processing and mosaicking algorithms, there has been limited work on localization of the probe to assist with building high quality mosaics over large areas of tissue. In this paper, we propose the use of electromagnetic (EM) navigation to assist with large-area mosaicking of hand-held high-resolution endomicroscopy probes. A six degree-of-freedom EM sensor is used to track in real-time the position and orientation of the tip of the imaging probe during free-hand scanning. We present a proof-of-principle system for EM-video data co-calibration and registration and then describe a two-step image registration algorithm that assists mosaic reconstruction. Preliminary experimental investigations are carried out on phantoms and ex vivo porcine tissue for free-hand scanning. The results demonstrate that the proposed methodology significantly improves the quality and accuracy of reconstructed mosaics compared to reconstructions based only on conventional pair-wise image registration. In principle, this approach can be applied to other optical biopsy techniques such as confocal endomicroscopy and endocytoscopy. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
  • Zuo, S. et al. (2014). Development of a large area scanner for intraoperative breast endomicroscopy. in: 2014 IEEE International Conference on Robotics and Automation (ICRA). pp. 3524-3530. Available at: https://doi.org/10.1109/ICRA.2014.6907367.
    Recent work on probe-based confocal endomicroscopy has demonstrated its potential role for real-time assessment of tumour margins during breast conserving surgery. However, endomicroscope probes tend to have a very small field-of-view, making surveillance of large areas of tissue difficult, and limiting practical clinical deployment. In this paper, a new robotic device for controlled, large area scanning based on a fibre bundle endomicroscope probe is proposed. The prototype uses a 2-DOF mechanism (-90 to +90 degrees bending on one axis, 360 degrees of rotation on a second axis) as well as a passive linear structure to conform to undulating surfaces. Both axes are driven by brushless DC servo motors with computer control, thus facilitating large field-of-view mosaicing. Experimental results have shown good repeatability and low hysteresis of the device, which is able to scan different surface trajectories (e.g. a spiral pattern over a hemi-spherical surface) with consistent tissue contact. Ex vivo human breast tissue results are demonstrated, illustrating a viable scanning approach for breast endomicroscopy.
  • Hughes, M. et al. (2013). Dual mode fibre bundle confocal endomicroscopy: combining reflectance and fluorescence imaging. in: SPIE, Advanced Microscopy Techniques III.. Available at: https://doi.org/10.1117/12.2032551.
    Commercial endomicroscopes operate in fluorescence mode only and so require the application of contrast agents. As an alternative, we describe a fibre bundle confocal endomicroscope which acquires simultaneous and co-registered fluorescence and reflectance mode images. A combination of polarisation selection and refractive index matching is used to minimise back-reflections from the fibre bundle. We show preliminary results from the system using phantoms and tissue samples. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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