Imaging
The Centre has a long history of developing new techniques for medical imaging (particularly in magnetic resonance imaging), transforming them from a primarily diagnostic modality into an interventional and therapeutic platform. This is facilitated by the Centre's strong engineering background in practical imaging and image analysis platform development, as well as advances in minimal access and robotic assisted surgery. Hamlyn has a strong tradition in pursuing basic sciences and theoretical research, with a clear focus on clinical translation.
In response to the current paradigm shift and clinical demand in bringing cellular and molecular imaging modalities to an in vivo – in situ setting during surgical intervention, our recent research has also been focussed on novel biophotonics platforms that can be used for real-time tissue characterisation, functional assessment, and intraoperative guidance during minimally invasive surgery. This includes, for example, SMART confocal laser endomicroscopy, time-resolved fluorescence spectroscopy and flexible FLIM catheters.
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Journal articleBrunckhorst O, Ong QJ, Elson D, et al., 2019,
Novel real-time optical imaging modalities for the detection of neoplastic lesions in urology: a systematic review
, Surgical Endoscopy, Vol: 33, Pages: 1349-1367, ISSN: 0930-2794Background Current optical diagnostic techniques for malignancies are limited in their diagnostic accuracy and lack theability to further characterise disease, leading to the rapidly increasing development of novel imaging methods within urology. This systematic review critically appraises the literature for novel imagining modalities, in the detection and staging ofurological cancer and assesses their effectiveness via their utility and accuracy.Methods A systematic literature search utilising MEDLINE, EMBASE and Cochrane Library Database was conducted from1970 to September 2018 by two independent reviewers. Studies were included if they assessed real-time imaging modalities not already approved in guidelines, in vivo and in humans. Outcome measures included diagnostic accuracy and utilityparameters, including feasibility and cost.Results Of 5475 articles identified from screening, a final 46 were included. Imaging modalities for bladder cancer includedoptical coherence tomography (OCT), confocal laser endomicroscopy, autofluorescence and spectroscopic techniques. OCTwas the most widely investigated, with 12 studies demonstrating improvements in overall diagnostic accuracy (sensitivity74.5–100% and specificity 60–98.5%). Upper urinary tract malignancy diagnosis was assessed using photodynamic diagnosis(PDD), narrow band imaging, optical coherence tomography and confocal laser endomicroscopy. Only PDD demonstratedconsistent improvements in overall diagnostic accuracy in five trials (sensitivity 94–96% and specificity 96.6–100%). Limitedevidence for optical coherence tomography in percutaneous renal biopsy was identified, with anecdotal evidence for anymodality in penile cancer.Conclusions Evidence supporting the efficacy for identified novel imaging modalities remains limited at present. However,OCT for bladder cancer and PDD in upper tract malignancy demonstrate the best potential for improvement in overall diagnostic accuracy. OCT may addit
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Journal articleQi J, Elson D, Stoyanov D, 2019,
An eigen value calibration method and optimization for 3×3 Mueller polarimeters
, Optics Letters, Vol: 44, Pages: 2362-2365, ISSN: 0146-95923×3 Mueller polarimetry has shown potential for tissue characterization applications, however, calibration has not been fully addressed. We demonstrate a 3×3 Mueller polarimeter eigenvalue calibration method, inspired by those for full Mueller polarimeters. We also investigate the optimal combination of calibration measurements. Our method does not rely on modeling the polarization state generator, polarization state analyzer, or precise knowledge of calibration sample properties or orientations. It is therefore easy to implement, and the experimental results of a linear polarizer test sample, as well as a biological specimen, are presented.
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Journal articleLin J, Walsted ES, Backer V, et al., 2019,
Quantification and analysis of laryngeal closure from endoscopic videos
, IEEE Transactions on Biomedical Engineering, Vol: 66, Pages: 1127-1136, ISSN: 0018-9294Objective: At present, there are no objective techniques to quantify and describe laryngeal obstruction, and the reproducibility of subjective manual quantification methods is insufficient, resulting in diagnostic inaccuracy and a poor signal-to-noise ratio in medical research. In this work, a workflow is proposed to quantify laryngeal movements from laryngoscopic videos, to facilitate the diagnosis procedure. Methods: The proposed method analyses laryngoscopic videos, and delineates glottic opening, vocal folds, and supraglottic structures, using a convolutional neural networks (CNNs) based algorithm. The segmentation is divided into two steps: A bounding box which indicates the region of interest (RoI) is found, followed by segmentation using fully convolutional networks (FCNs). The segmentation results are statistically quantified along the temporal dimension and processed using singular spectrum analysis (SSA), to extract clear objective information that can be used by the clinicians in diagnosis. Results: The segmentation was validated on 400 images from 20 videos acquired using different endoscopic systems from different patients. The results indicated significant improvements over using FCN only in terms of both processing speed (16 FPS vs. 8 FPS) and segmentation result statistics. Five clinical cases on patients have also been provided to showcase the quantitative analysis results using the proposed method. Conclusion: The proposed method guarantees a robust and fast processing of laryngoscopic videos. Measurements of glottic angles and supraglottic index showed distinctive patterns in the provided clinical cases. Significance: The proposed automated and objective method extracts important temporal laryngeal movement information, which can be used to aid laryngeal closure diagnosis.
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Journal articleSheng W, Li W, Qi J, et al., 2019,
Quantitative analysis of 4 x 4 Mueller matrix transformation parameters for biomedical imaging
, Photonics, Vol: 6, ISSN: 2304-6732Mueller matrix polarimetry is a potentially powerful technique for obtaining microstructural information of biomedical specimens. Thus, it has found increasing application in both backscattering imaging of bulk tissue samples and transmission microscopic imaging of thin tissue slices. Recently, we proposed a technique to transform the 4 × 4 Mueller matrix elements into a group of parameters, which have explicit associations with specific microstructural features of samples. In this paper, we thoroughly analyze the relationships between the Mueller matrix transformation parameters and the characteristic microstructures of tissues by using experimental phantoms and Monte Carlo simulations based on different tissue mimicking models. We also adopt quantitative evaluation indicators to compare the Mueller matrix transformation parameters with the Mueller matrix polar decomposition parameters. The preliminary imaging results of bulk porcine colon tissues and thin human pathological tissue slices demonstrate the potential of Mueller matrix transformation parameters as biomedical diagnostic indicators. Also, this study provides quantitative criteria for parameter selection in biomedical Mueller matrix imaging.
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Conference paperKim JA, Wales DJ, Thompson AJ, et al., 2019,
Towards development of fibre-optic surface enhanced Raman spectroscopy probes using 2-photon polymerisation for rapid detection of bacteria
, Plasmonics in Biology and Medicine XVI, Publisher: SPIE, ISSN: 0277-786XIn this study, a variety of direct laser written surface-enhanced Raman spectroscopy (SERS) micro-structures, designed for bacteria detection, are presented. Various SERS micro-structures were designed to achieve both a high density of plasmonic hot spots and a strong probability of interaction between the hot spots and the target bacterial cells. Twophoton polymerization was used for initial fabrication of the polymeric skeletons of the SERS micro-structures, which were then coated with a 50 nm-thick gold layer via e-beam evaporation. The micro-structures were fabricated on glass coverslips and were assessed using a confocal Raman microscope. To this end, Rhodamine 6G was used as an analyte under 785 nm laser illumination. The optimal SERS micro-structures showed approximately 7×103 enhancement in Raman signal (analytical enhancement factor, AEF) at a wavenumber of 600 cm-1. Real-time detection of E. coli in solution was demonstrated using the fabricated SERS platform with low laser powers and a short acquisition time (785 nm, 5 mW, 50 ms).
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