Imperial College London

Prof Guang-Zhong Yang

Faculty of EngineeringDepartment of Computing

Director, The Hamlyn Centre
 
 
 
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Contact

 

+44 (0)20 7594 1499g.z.yang Website

 
 
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Assistant

 

Miss Raphaele Raupp +44 (0)20 7594 1499

 
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Location

 

B411-412Bessemer BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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971 results found

Deligianni F, Wong C, Lo B, Yang G-Zet al., 2018, A fusion framework to estimate plantar ground force distributions and ankle dynamics, Information Fusion, Vol: 41, Pages: 255-263, ISSN: 1566-2535

JOURNAL ARTICLE

Orihuela-Espina F, Leff DR, James DRC, Darzi AW, Yang G-Zet al., 2018, Imperial College near infrared spectroscopy neuroimaging analysis framework., Neurophotonics, Vol: 5, ISSN: 2329-423X

This paper describes the Imperial College near infrared spectroscopy neuroimaging analysis (ICNNA) software tool for functional near infrared spectroscopy neuroimaging data. ICNNA is a MATLAB-based object-oriented framework encompassing an application programming interface and a graphical user interface. ICNNA incorporates reconstruction based on the modified Beer-Lambert law and basic processing and data validation capabilities. Emphasis is placed on the full experiment rather than individual neuroimages as the central element of analysis. The software offers three types of analyses including classical statistical methods based on comparison of changes in relative concentrations of hemoglobin between the task and baseline periods, graph theory-based metrics of connectivity and, distinctively, an analysis approach based on manifold embedding. This paper presents the different capabilities of ICNNA in its current version.

JOURNAL ARTICLE

Anastasova S, Crewther B, Bembnowicz P, Curto V, Ip HM, Rosa B, Yang G-Zet al., 2017, A wearable multisensing patch for continuous sweat monitoring (vol 93, pg 139, 2017), BIOSENSORS & BIOELECTRONICS, Vol: 94, Pages: 730-730, ISSN: 0956-5663

JOURNAL ARTICLE

Anastasova S, Crewther B, Bembnowicz P, Curto V, Ip HMD, Rosa B, Yang G-Zet al., 2017, A wearable multisensing patch for continuous sweat monitoring, BIOSENSORS & BIOELECTRONICS, Vol: 93, Pages: 139-145, ISSN: 0956-5663

JOURNAL ARTICLE

Anastasova S, Kassanos P, Yang G-Z, 2017, Multi-parametric rigid and flexible, low-cost, disposable sensing platforms for biomedical applications., Biosens Bioelectron

The measurement of Na+, K+ and H+ is essential in medicine and plays an important role in the assessment of tissue ischemia. Microfabrication, inkjet- and screen-printing can be used for solid contact ion selective electrodes (ISE) realization; these, however, can be non-standardized, costly and time consuming processes. We present the realization of ISEs on post-processed electrodes fabricated via standardized printed circuit board (PCB) manufacturing techniques. In vitro results are presented from two rigid platforms (32 ISEs) for liquid sample dip-stick measurements and two flexible platforms (6 and 32 ISEs) for post-surgical intestinal tissue monitoring, each with a common reference electrode (RE). These are combined with optimized tetrapolar bioimpedance sensors for tissue ischemia detection. Both electroless and hard gold PCB finishes are examined. Apart from the electroless rigid platform, the rest demonstrated comparable and superior performance, with the pH sensors demonstrating the greatest deviation; the flexible hard gold platform achieved a sensitivity 4.6mV/pH and 49.2mV/pH greater than the electroless flexible and rigid platforms, respectively. The best overall performance was achieved with the hard gold flexible platform with sensitivities as large as 73.4mV/pH, 56.3mV/log [Na+], and 57.4mV/log [K+] vs. custom REs on the same substrate. Simultaneous measurement of target analytes is demonstrated with test solutions and saliva samples. The results demonstrate superior performance to other PCB-based pH sensors and Na+ and K+ PCB-based sensors with comparable performance to potentiometric sensors fabricated with other techniques, paving the way towards mass-produced, low-cost, disposable, multi-parametric chemical sensing diagnostic platforms.

JOURNAL ARTICLE

Andreu-Perez J, Garcia-Gancedo L, McKinnell J, Van der Drift A, Powell A, Hamy V, Keller T, Yang G-Zet al., 2017, Developing Fine-Grained Actigraphies for Rheumatoid Arthritis Patients from a Single Accelerometer Using Machine Learning, SENSORS, Vol: 17, ISSN: 1424-8220

JOURNAL ARTICLE

Avci E, Grammatikopoulou M, Yang G-Z, 2017, Laser-Printing and 3D Optical-Control of Untethered Microrobots, ADVANCED OPTICAL MATERIALS, Vol: 5, ISSN: 2195-1071

JOURNAL ARTICLE

Bao S-D, Chen M, Yang G-Z, 2017, A Method of Signal Scrambling to Secure Data Storage for Healthcare Applications, IEEE JOURNAL OF BIOMEDICAL AND HEALTH INFORMATICS, Vol: 21, Pages: 1487-1494, ISSN: 2168-2194

JOURNAL ARTICLE

Berthelot M, Yang G-Z, Lo B, 2017, Preliminary Study for Hemodynamics Monitoring using a Wearable Device Network, 14th Annual IEEE International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE, Pages: 115-118, ISSN: 2376-8886

CONFERENCE PAPER

Berthelot ME, Yang GZ, Lo B, 2017, A self-calibrated tissue viability sensor for free flap monitoring, IEEE Journal of Biomedical and Health Informatics, ISSN: 2168-2194

In fasciocutaneous free flap surgery, close postoperative monitoring is crucial for detecting flap failure, as around 10% of cases require additional surgery due to compromised anastomosis. Different biochemical and biophysical techniques have been developed for continuous flap monitoring, however, they all have shortcoming in terms of reliability, elevated cost, potential risks to the patient and inability to adapt to the patient's phenotype. A wearable wireless device based on near infrared spectroscopy (NIRS) has been developed for continuous blood flow and perfusion monitoring by quantifying tissue oxygen saturation (StO2). This miniaturized and low cost device is designed for postoperative monitoring of flap viability. With self-calibration, the device can adapt itself to the characteristics of the patients' skin such as tone and thickness. An extensive study was conducted with 32 volunteers. The experimental results show that the device can obtain reliable StO2 measurements across different phenotypes (age, sex, skin tone and thickness). To assess its ability to detect flap failure, the sensor was validated with an animal study. Free groin flaps were performed on 16 Sprague Dawley rats. Results demonstrate the accuracy of the sensor in assessing flap viability and identifying the origin of failure (venous or arterial thrombosis).

JOURNAL ARTICLE

Chi W, Rafii-Tari H, Payne CJ, Liu J, Riga C, Bicknell C, Yang GZet al., 2017, A learning based training and skill assessment platform with haptic guidance for endovascular catheterization, Pages: 2357-2363, ISSN: 1050-4729

© 2017 IEEE. Increasing demands in endovascular intervention have motivated technical skill training and competency-based measures of performance. However, there are no well-established online metrics for technical skill assessment; few studies have explored operator behavioral patterns from catheter motion and operator hand motions. This paper proposes a platform for active online training and objective assessment of endovascular skills, through learning optimum catheter motions from multiple demonstrations. An ungrounded hand-held haptic device for providing intuitive haptic guidance to novice users based on this learnt information is also proposed. Statistical models are implemented to extract the underlying catheter motion patterns, and utilize them for performance evaluation and haptic guidance. The results show significant improvements in endovascular navigation for inexperienced operators. Finer catheter motions were achieved with the provided haptic guidance. The results suggest that the proposed platform can be integrated into current clinical training setups, and motivate the improvement of endovascular training platforms with better realism.

CONFERENCE PAPER

Constantinescu M, Lee SL, Ernst S, Yang GZet al., 2017, Statistical atlases for electroanatomical mapping of cardiac arrhythmias, Pages: 301-310, ISSN: 0302-9743

© Springer International Publishing AG 2017. Electroanatomical mapping is a mandatory time-consuming planning step in cardiac catheter ablation. In practice, interventional cardiologists target specific endocardial areas for mapping based on personal experience, general electrophysiology principles, and preoperative anatomical scans. Effective fusion of all available information towards a useful mapping strategy has not been standardised and achieving the optimal map within time and space constraints is challenging. In this paper, a novel framework for computing optimal endocardial mapping locations in patients with congenital heart disease (CHD) is proposed. The method is based on a statistical electroanatomical model (SEAM) which is instantiated from preoperative anatomy in order to achieve an initial prediction of the electrical map. Simultaneously, the anatomical areas with the highest frequency of mapping among the similar cases in the dataset are detected and a classifier is trained to filter these points based on the electroanatomical data. The framework was tested in an iterative process of adding mapping points to the SEAM and computing the instantiation error, with retrospective clinical data of 66 CHD cases available.

CONFERENCE PAPER

Freer DR, Liu J, Yang G-Z, 2017, Optimization of EMG Movement Recognization for Use in an Upper Limb Wearable Robot, 14th Annual IEEE International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE, Pages: 202-205, ISSN: 2376-8886

CONFERENCE PAPER

Gambini J, Quinn T, Vila R, Matalonga S, Hermida J, Alonso O, Cossa J, Hughes M, Leff D, Yang GZ, Cabral Pet al., 2017, Upgraded portable Indocyanine Green (ICG) detection system - towards Image Guided Cancer Surgery, Annual Meeting of the Society-of-Nuclear-Medicine-and-Molecular-Imaging (SNMMI), Publisher: SOC NUCLEAR MEDICINE INC, ISSN: 0161-5505

CONFERENCE PAPER

Gil Rosa BM, Yang GZ, 2017, Imaging from the implantable side: Ultrasonic-powered EIT system for surgical site infection detection, Ultrasonics Symposium (IUS), 2017 IEEE International, Publisher: IEEE, ISSN: 1948-5727

Abstract:Ultrasounds (US) are a proven medical tool to assess a myriad of biological processes, including breast cancer screening, fetal development and blood flow. However, US also have the potential to deliver power and telemetry capability to deeply implanted devices, surpassing some challenges faced by coils or antennas operating inside the human body. In this study we present an implantable device powered by US that can perform in situ tissue impedance imaging. The objective is to provide a tool to evaluate soft tissue healing after surgery, by searching for areas of bacterial infection as the normal conductivity of tissue will be impaired, undetectable by standard imaging methods. The motivation is to reduce not only the morbidity rate associated with wound infections (1/3 of the postoperative deaths) but also to shorten patient's recovery time in hospital, with 5% risk of developing a new infection.

CONFERENCE PAPER

Grammatikopoulou M, Yang GZ, 2017, Gaze contingent control for optical micromanipulation, Pages: 5989-5995, ISSN: 1050-4729

© 2017 IEEE. Optical Tweezers (OT) have the advantage of non-contact interaction with target objects such as cells, overcoming the pitfall of obstructive adhesion forces which are present in contact micromanipulation. It is also feasible to manipulate a number of small microparts simultaneously or 3D structures by using multiple laser traps. These capabilities give rise to the potential to develop a human-robot interface to facilitate microassembly tasks. This paper presents a gaze contingent control framework and a method for 3D orientation estimation for optical micromanipulation. The proposed strategy aims to use OT as an interactive microassembly platform. The framework comprises I) a strategy to recognize the operator's intentions in order to interactively place and reconfigure the optical traps using the operator's eye fixation point, II) haptic constraints generated from the user's eye gaze to assist positioning of the assembled microparts and III) a method for 3D orientation estimation. The performance of the proposed framework is assessed through a set of experiments comparing it to the standard OT user interface. Three-dimensional manipulation and orientation estimation of a non-spherical microstructure are also performed.

CONFERENCE PAPER

Gras G, Leibrandt K, Wisanuvej P, Giataganas P, Seneci CA, Ye M, Shang J, Yang GZet al., 2017, Implicit gaze-assisted adaptive motion scaling for highly articulated instrument manipulation, Pages: 4233-4239, ISSN: 1050-4729

© 2017 IEEE. Traditional robotic surgical systems rely entirely on robotic arms to triangulate articulated instruments inside the human anatomy. This configuration can be ill-suited for working in tight spaces or during single access approaches, where little to no triangulation between the instrument shafts is possible. The control of these instruments is further obstructed by ergonomic issues: The presence of motion scaling imposes the use of clutching mechanics to avoid the workspace limitations of master devices, and forces the user to choose between slow, precise movements, or fast, less accurate ones. This paper presents a bi-manual system using novel self-triangulating 6-degrees-of-freedom (DoF) tools through a flexible elbow, which are mounted on robotic arms. The control scheme for the resulting 9-DoF system is detailed, with particular emphasis placed on retaining maximum dexterity close to joint limits. Furthermore, this paper introduces the concept of gaze-assisted adaptive motion scaling. By combining eye tracking with hand motion and instrument information, the system is capable of inferring the user's destination and modifying the motion scaling accordingly. This safe, novel approach allows the user to quickly reach distant locations while retaining full precision for delicate manoeuvres. The performance and usability of this adaptive motion scaling is evaluated in a user study, showing a clear improvement in task completion speed and in the reduction of the need for clutching.

CONFERENCE PAPER

Gu Y, Vyas K, Yang J, Yang GZet al., 2017, Unsupervised feature learning for endomicroscopy image retrieval, Pages: 64-71, ISSN: 0302-9743

© Springer International Publishing AG 2017. Learning the visual representation for medical images is a critical task in computer-aided diagnosis. In this paper, we propose Unsupervised Multimodal Graph Mining (UMGM) to learn the discriminative features for probe-based confocal laser endomicroscopy (pCLE) mosaics of breast tissue. We build a multiscale multimodal graph based on both pCLE mosaics and histology images. The positive pairs are mined via cycle consistency and the negative pairs are extracted based on geodetic distance. Given the positive and negative pairs, the latent feature space is discovered by reconstructing the similarity between pCLE and histology images. Experiments on a database with 700 pCLE mosaics demonstrate that the proposed method outperforms previous works on pCLE feature learning. Specially, the top-1 accuracy in an eight-class retrieval task is 0.659 which leads to 10% improvement compared with the state-of-the-art method.

CONFERENCE PAPER

Huang B, ye M, hu Y, vandini A, lee S, yang Get al., 2017, A Multi-Robot Cooperation Framework for Sewing Personalized Stent Grafts, IEEE Transactions on Industrial Informatics, ISSN: 1551-3203

This paper presents a multi-robot system for manufacturing personalized medical stent grafts. The proposed system adopts a modular design, which includes: a (personalized) mandrel module, a bimanual sewing module, and a vision module. The mandrel module incorporates the personalized geometry of patients, while the bimanual sewing module adopts a learning-by-demonstration approach to transfer human hand-sewing skills to the robots. The human demonstrations were firstly observed by the vision module and then encoded using a statistical model to generate the reference motion trajectories. During autonomous robot sewing, the vision module plays the role of coordinating multi-robot collaboration. Experiment results show that the robots can adapt to generalized stent designs. The proposed system can also be used for other manipulation tasks, especially for flexible production of customized products and where bimanual or multi-robot cooperation is required.

JOURNAL ARTICLE

Leff DR, Yongue G, Vlaev I, Orihuela-Espina F, James D, Taylor MJ, Athanasiou T, Dolan R, Yang G-Z, Darzi Aet al., 2017, "Contemplating the Next Maneuver" Functional Neuroimaging Reveals Intraoperative Decision-making Strategies, ANNALS OF SURGERY, Vol: 265, Pages: 320-330, ISSN: 0003-4932

JOURNAL ARTICLE

Leibrandt K, Bergeles C, Yang G-Z, 2017, Concentric Tube Robots Rapid, Stable Path-Planning and Guidance for Surgical Use, IEEE ROBOTICS & AUTOMATION MAGAZINE, Vol: 24, Pages: 42-53, ISSN: 1070-9932

JOURNAL ARTICLE

Leibrandt K, Wisanuvej P, Gras G, Shang J, Seneci CA, Giataganas P, Vitiello V, Darzi A, Yang G-Zet al., 2017, Effective Manipulation in Confined Spaces of Highly Articulated Robotic Instruments for Single Access Surgery, IEEE ROBOTICS AND AUTOMATION LETTERS, Vol: 2, Pages: 1704-1711, ISSN: 2377-3766

JOURNAL ARTICLE

Leibrandt K, Yang G-Z, 2017, Efficient Proximity Queries for Continuum Robots on Parallel Computing Hardware, IEEE ROBOTICS AND AUTOMATION LETTERS, Vol: 2, Pages: 1548-1555, ISSN: 2377-3766

JOURNAL ARTICLE

Leonhardt S, Yang GZ, Habetha J, 2017, Welcome message

CONFERENCE PAPER

Marcus HJ, Hughes-Hallett A, Payne CJ, Cundy TP, Nandi D, Yang G-Z, Darzi Aet al., 2017, Trends in the diffusion of robotic surgery: A retrospective observational study., Int J Med Robot, Vol: 13

BACKGROUND: Recent studies have suggested that the use of robotic surgery for prostatectomy has been increasing, but characterization of the diffusion of robotic surgery in other procedures has not been available. METHODS: Data were analysed for the years 2006-2014 using hospital episode statistics (HES), a database of all admissions to National Health Service (NHS) hospitals in England. OPCS codes were used to determine the annual number of prostatectomy, partial nephrectomy, and total abdominal hysterectomy procedures. Concurrent OPCS codes were then used to identify whether these procedures were robotic, conventional laparoscopic or open surgery. RESULTS: The proportion of robotic cases varied depending on the surgical procedure. Diffusion of robotic surgery was relatively rapid in prostatectomy, moderate in partial nephrectomy, and slow in total abdominal hysterectomy. CONCLUSIONS: Although high institutional cost might explain the earliest delays in diffusion, this barrier does not fully account for the different rates of diffusion among surgical procedures.

JOURNAL ARTICLE

Modi HN, Singh H, Orihuela-Espina F, Athanasiou T, Fiorentino F, Yang G-Z, Darzi A, Leff DRet al., 2017, Temporal Stress in the Operating Room: Brain Engagement Promotes "Coping" and Disengagement Prompts "Choking"., Ann Surg

OBJECTIVE: To investigate the impact of time pressure (TP) on prefrontal activation and technical performance in surgical residents during a laparoscopic suturing task. BACKGROUND: Neural mechanisms enabling surgeons to maintain performance and cope with operative stressors are unclear. The prefrontal cortex (PFC) is implicated due to its role in attention, concentration, and performance monitoring. METHODS: A total of 33 residents [Postgraduate Year (PGY)1-2 = 15, PGY3-4 = 8, and PGY5 = 10] performed a laparoscopic suturing task under "self-paced" (SP) and "TP" conditions (TP = maximum 2 minutes per knot). Subjective workload was quantified using the Surgical Task Load Index. PFC activation was inferred using optical neuroimaging. Technical skill was assessed using progression scores (au), error scores (mm), leak volumes (mL), and knot tensile strengths (N). RESULTS: TP led to greater perceived workload amongst all residents (mean Surgical Task Load Index score ± SD: PGY1-2: SP = 160.3 ± 24.8 vs TP = 202.1 ± 45.4, P < 0.001; PGY3-4: SP = 123.0 ± 52.0 vs TP = 172.5 ± 43.1, P < 0.01; PGY5: SP = 105.8 ± 55.3 vs TP = 159.1 ± 63.1, P < 0.05). Amongst PGY1-2 and PGY3-4, deterioration in task progression, error scores and knot tensile strength (P < 0.05), and diminished PFC activation was observed under TP. In PGY5, TP resulted in inferior task progression and error scores (P < 0.05), but preservation of knot tensile strength. Furthermore, PGY5 exhibited less attenuation of PFC activation under TP, and greater activation than either PGY1-2 or PGY3-4 under both experimental conditions (P < 0.05). CONCLUSIONS: Senior residents cope better with temporal demands and exhibit greater technical performance stability under pressure, possibly due to sustained PFC activation and greater task engagement. Future work should seek to develop training strategies that recruit prefrontal resources, enha

JOURNAL ARTICLE

Modi HN, Singh H, Yang G-Z, Darzi A, Leff DRet al., 2017, A decade of imaging surgeons' brain function (part I): Terminology, techniques, and clinical translation, SURGERY, Vol: 162, Pages: 1121-1130, ISSN: 0039-6060

JOURNAL ARTICLE

Modi HN, Singh H, Yang G-Z, Darzi A, Leff DRet al., 2017, A decade of imaging surgeons' brain function (part II): A systematic review of applications for technical and nontechnical skills assessment, SURGERY, Vol: 162, Pages: 1130-1139, ISSN: 0039-6060

JOURNAL ARTICLE

Palamidas AF, Kemp SV, Shen M, McNulty W, Zoumot Z, Hopkinson NS, Yang G-Z, Shah PLet al., 2017, Putative Mechanisms of Action of Endobronchial Coils, AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE, Vol: 196, Pages: 109-115, ISSN: 1073-449X

JOURNAL ARTICLE

Peters T, Yang GZ, Navab N, Mori K, Luo X, Reichl T, McLeod Jet al., 2017, Preface, ISBN: 9783319540566

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