Imperial College London

DrPhilipPratt

Faculty of MedicineDepartment of Surgery & Cancer

 
 
 
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Contact

 

+44 (0)20 3312 5525p.pratt Website

 
 
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Location

 

005Paterson WingSt Mary's Campus

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Summary

 

Publications

Publication Type
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74 results found

Feather C, Appelbaum N, Clarke J, Franklin B, Sinha R, Pratt P, Maconochie I, Darzi Aet al., Medication errors during simulated paediatric resuscitations: a prospective, observational human reliability analysis, BMJ Open, ISSN: 2044-6055

Introduction: Medication errors during paediatric resuscitation are thought to be common. However, there is little evidence about the individual process steps that contribute to such medication errors in this context.Objectives: To describe the incidence, nature and severity of medication errors in simulated paediatric resuscitations, and to employ human reliability analysis to understand the contribution of discrepancies in individual process steps to the occurrence of these errors.Methods: We conducted a prospective observational study of simulated resuscitations subjected to video micro-analysis, identification of medication errors, severity assessment and human reliability analysis in a large English teaching hospital. Fifteen resuscitation teams of two doctors and two nurses each conducted one of two simulated paediatric resuscitation scenarios. Results: At least one medication error was observed in every simulated case, and a large magnitude (>25% discrepant) or clinically significant error in 11 of 15 cases. Medication errors were observed in 29% of 180 simulated medication administrations, 40% of which considered to be moderate or severe. These errors were the result of 884 observed discrepancies at a number of steps in the drug ordering, preparation and administration stages of medication use, 8% of which made a major contribution to a resultant medication error. Most errors were introduced by discrepancies during drug preparation and administration. Conclusions: Medication errors were common with a considerable proportion likely to result in patient harm. There is an urgent need to optimise existing systems and to commission research into new approaches to increase the reliability of human interactions during administration of medication in the paediatric emergency setting.

Journal article

Dawda S, Camara M, Pratt P, Vale J, Darzi A, Mayer Eet al., 2019, Patient-specific simulation of pneumoperitoneum for laparoscopic surgical planning, Journal of Medical Systems, Vol: 43, ISSN: 0148-5598

Gas insufflation in laparoscopy deforms the abdomen and stretches the overlying skin. This limits the use of surgical image-guidance technologies and challenges the appropriate placement of trocars, which influences the operative ease and potential quality of laparoscopic surgery. This work describes the development of a platform that simulates pneumoperitoneum in a patient-specific manner, using preoperative CT scans as input data. This aims to provide a more realistic representation of the intraoperative scenario and guide trocar positioning to optimize the ergonomics of laparoscopic instrumentation. The simulation was developed by generating 3D reconstructions of insufflated and deflated porcine CT scans and simulating an artificial pneumoperitoneum on the deflated model. Simulation parameters were optimized by minimizing the discrepancy between the simulated pneumoperitoneum and the ground truth model extracted from insufflated porcine scans. Insufflation modeling in humans was investigated by correlating the simulation’s output to real post-insufflation measurements obtained from patients in theatre. The simulation returned an average error of 7.26 mm and 10.5 mm in the most and least accurate datasets respectively. In context of the initial discrepancy without simulation (23.8 mm and 19.6 mm), the methods proposed here provide a significantly improved picture of the intraoperative scenario. The framework was also demonstrated capable of simulating pneumoperitoneum in humans. This study proposes a method for realistically simulating pneumoperitoneum to achieve optimal ergonomics during laparoscopy. Although further studies to validate the simulation in humans are needed, there is the opportunity to provide a more realistic, interactive simulation platform for future image-guided minimally invasive surgery.

Journal article

Dilley J, Camara M, Omar I, Carter A, Pratt P, Vale J, Darzi A, Mayer EKet al., 2019, Evaluating the impact of image guidance in the surgical setting: A systematic review, Surgical Endoscopy, Vol: 33, Pages: 2785-2793, ISSN: 0930-2794

BACKGROUND: Image guidance has been clinically available for over a period of 20 years. Although research increasingly has a translational emphasis, overall the clinical uptake of image guidance systems in surgery remains low. The objective of this review was to establish the metrics used to report on the impact of surgical image guidance systems used in a clinical setting. METHODS: A systematic review of the literature was carried out on all relevant publications between January 2000 and April 2016. Ovid MEDLINE and Embase databases were searched using a title strategy. Reported outcome metrics were grouped into clinically relevant domains and subsequent sub-categories for analysis. RESULTS: In total, 232 publications were eligible for inclusion. Analysis showed that clinical outcomes and system interaction were consistently reported. However, metrics focusing on surgeon, patient and economic impact were reported less often. No increase in the quality of reporting was observed during the study time period, associated with study design, or when the clinical setting involved a surgical specialty that had been using image guidance for longer. CONCLUSIONS: Publications reporting on the clinical use of image guidance systems are evaluating traditional surgical outcomes and neglecting important human and economic factors, which are pertinent to the uptake, diffusion and sustainability of image-guided surgery. A framework is proposed to assist researchers in providing comprehensive evaluation metrics, which should also be considered in the design phase. Use of these would help demonstrate the impact in the clinical setting leading to increased clinical integration of image guidance systems.

Journal article

Camara M, Dawda S, Mayer E, Darzi A, Pratt Pet al., 2019, Subject-specific modelling of pneumoperitoneum: model implementation, validation and human feasibility assessment, International Journal of Computer Assisted Radiology and Surgery, Vol: 14, Pages: 841-850, ISSN: 1861-6429

PURPOSE: The aim of this study is to propose a model that simulates patient-specific anatomical changes resulting from pneumoperitoneum, using preoperative data as input. The framework can assist the surgeon through a real-time visualisation and interaction with the model. Such could further facilitate surgical planning preoperatively, by defining a surgical strategy, and intraoperatively to estimate port positions. METHODS: The biomechanical model that simulates pneumoperitoneum was implemented within the GPU-accelerated NVIDIA FleX position-based dynamics framework. Datasets of multiple porcine subjects before and after abdominal insufflation were used to generate, calibrate and validate the model. The feasibility of modelling pneumoperitoneum in human subjects was assessed by comparing distances between specific landmarks from a patient abdominal wall, to the same landmark measurements on the simulated model. RESULTS: The calibration of simulation parameters resulted in a successful estimation of an optimal set parameters. A correspondence between the simulation pressure parameter and the experimental insufflation pressure was determined. The simulation of pneumoperitoneum in a porcine subject resulted in a mean Hausdorff distance error of 5-6 mm. Feasibility of modelling pneumoperitoneum in humans was successfully demonstrated. CONCLUSION: Simulation of pneumoperitoneum provides an accurate subject-specific 3D model of the inflated abdomen, which is a more realistic representation of the intraoperative scenario when compared to preoperative imaging alone. The simulation results in a stable and interactive framework that performs in real time, and supports patient-specific data, which can assist in surgical planning.

Journal article

Camara M, Mayer E, Darzi A, Pratt Pet al., 2019, Intraoperative ultrasound for improved 3D tumour reconstruction in robot-assisted surgery: An evaluation of feedback modalities, International Journal of Medical Robotics and Computer Assisted Surgery, Vol: 15, Pages: 1-9, ISSN: 1478-5951

BACKGROUND: Intraoperative ultrasound scanning induces deformation on the tissue in the absence of a feedback modality, which results in a 3D tumour reconstruction that is not directly representative of real anatomy. METHODS: A biomechanical model with different feedback modalities (haptic, visual, or auditory) was implemented in a simulation environment. A user study with 20 clinicians was performed to assess which modality resulted in the 3D tumour volume reconstruction that most resembled the reference configuration from the respective computed tomography (CT) scans. RESULTS: Integrating a feedback modality significantly improved the scanning performance across all participants and data sets. The optimal feedback modality to adopt varied depending on the evaluation. Nonetheless, using guidance with feedback is always preferred compared with none. CONCLUSIONS: The results demonstrated the urgency to integrate a feedback modality framework into clinical practice, to ensure an improved scanning performance. Furthermore, this framework enabled an evaluation that cannot be performed in vivo.

Journal article

Dilley J, Hughes-Hallett A, Pratt P, Pucher P, Camara M, Darzi A, Mayer Eet al., 2019, Perfect registration leads to imperfect performance: a randomised trial of multimodal intraoperative image guidance, Annals of Surgery, Vol: 269, Pages: 236-242, ISSN: 0003-4932

Objective – To compare surgical safety and efficiency of two image guidance modalities, perfect augmented reality (AR) and side-by-side unregistered image guidance (IG), against a no guidance control (NG), when performing a simulated laparoscopic cholecystectomy (LC).Background – Image guidance using AR offers the potential to improve understanding of subsurface anatomy, with positive ramifications for surgical safety and efficiency. No intra-abdominal study has demonstrated any advantage for the technology. Perfect AR cannot be provided in the operative setting in a patient, however it can be generated in the simulated setting. Methods – Thirty six experienced surgeons performed a baseline LC using the LapMentor™ simulator before randomisation to one of three study arms: AR, IG or NG. Each performed three further LC. Safety and efficiency-related simulator metrics, and task workload (SURG-TLX) were collected. Results –The IG group had a shorter total instrument path length and fewer movements than NG and AR groups. Both IG and NG took a significantly shorter time than AR to complete dissection of Calot’s triangle. Use of IG and AR resulted in significantly fewer perforations and serious complications than the NG group. IG had significantly fewer perforations and serious complications than AR group. Compared to IG, AR guidance was found to be significantly more distracting. Conclusion – Side-by-side unregistered image guidance (IG) improved safety and surgical efficiency in a simulated setting when compared to AR or NG. IG provides a more tangible opportunity for integrating image guidance into existing surgical workflow as well as delivering the safety and efficiency benefits desired.

Journal article

Dilley J, Pratt P, Kyrgiou M, Flott K, Darzi A, Mayer Eet al., 2018, Current and future use of radiological images in the management of gynecological malignancies - a survey of practice in the UK, Anticancer Research, Vol: 38, Pages: 5867-5876, ISSN: 0250-7005

Background/Aim: Radiology provides increasingly accurate and complex information. Understanding the clinicians' interpretation of scans could improve surgical planning, decision-making; informed training and development of augmented imaging. This was a survey exploring the interpretation of imaging by clinicians and its use in operative preparation and prediction. Materials and Methods: The survey was open for two-months and circulated online to British Gynaecological Cancer society members. Results: Seventy-three (19%) members completed the survey. Respondents had a confidence level of 51% in their ability to interpret computed tomography (CT) and/or magnetic resonance imaging (MRI) images independently. Preoperative imaging was commonly used to plan operations, predict complications and complete resection. Images were reviewed for primary (96.3%)/interval (92.6%) ovarian debulking, but less so for vulvectomy (45%). Scan (79.6%) and multidisciplinary team meeting (MDT) (66.6%) reports were used more often than scan images (50%) for operative planning. Amount and pattern of disease on scan were the most important factors predicting operating time. Conclusion: Imaging influences the surgeon's planning, however respondents lack confidence. Training of clinicians in radiological interpretation needs to improve. Augmented image interfaces could facilitate this.

Journal article

Linte CA, Kersten-Oertel M, Yaniv Z, Xiao Y, Essert C, Jannin P, Lau J, Pratt P, Reinertsen I, Rivaz Het al., 2018, Guest Editorial: Papers from the 12th workshop on Augmented Environments for Computer-Assisted Interventions, HEALTHCARE TECHNOLOGY LETTERS, Vol: 5, Pages: 136-136, ISSN: 2053-3713

Journal article

Edgcumbe P, Singla R, Pratt P, Schneider C, Nguan C, Rohling Ret al., 2018, Follow the light: projector-based augmented reality intracorporeal system for laparoscopic surgery, JOURNAL OF MEDICAL IMAGING, Vol: 5, ISSN: 2329-4302

Journal article

Dilley J, Singh H, Pratt P, Darzi A, Mayer Eet al., Visual behaviour in robotic surgery – demonstrating the validity of the simulated environment, 8th Annual BIARGS Meeting

Conference paper

Pratt P, Ives M, Lawton G, Simmons J, Radev N, Spyropoulou L, Amiras Det al., 2018, Through the HoloLens looking glass: augmented reality for extremity reconstruction surgery using 3D vascular models with perforating vessels, European Radiology Experimental, Vol: 2, ISSN: 2509-9280

Precision and planning are key to reconstructive surgery. Augmented reality (AR) can bring the information within preoperative computed tomography angiography (CTA) imaging to life, allowing the surgeon to ‘see through’ the patient’s skin and appreciate the underlying anatomy without making a single incision. This work has demonstrated that AR can assist the accurate identification, dissection and execution of vascular pedunculated flaps during reconstructive surgery. Separate volumes of osseous, vascular, skin, soft tissue structures and relevant vascular perforators were delineated from preoperative CTA scans to generate three-dimensional images using two complementary segmentation software packages. These were converted to polygonal models and rendered by means of a custom application within the HoloLens™ stereo head-mounted display. Intraoperatively, the models were registered manually to their respective subjects by the operating surgeon using a combination of tracked hand gestures and voice commands; AR was used to aid navigation and accurate dissection. Identification of the subsurface location of vascular perforators through AR overlay was compared to the positions obtained by audible Doppler ultrasound. Through a preliminary HoloLens-assisted case series, the operating surgeon was able to demonstrate precise and efficient localisation of perforating vessels.

Journal article

Pratt P, Arora A, 2018, Transoral Robotic Surgery: Image Guidance and Augmented Reality, ORL-JOURNAL FOR OTO-RHINO-LARYNGOLOGY HEAD AND NECK SURGERY, Vol: 80, Pages: 204-212, ISSN: 0301-1569

Journal article

Fallavollita P, Kersten M, Linte CA, Pratt P, Yaniv Zet al., 2017, Special Issue on Augmented Environments for Computer-Assisted Interventions Foreword, HEALTHCARE TECHNOLOGY LETTERS, Vol: 4, Pages: 149-149, ISSN: 2053-3713

Journal article

Singla R, Edgcumbe P, Pratt P, Nguan C, Rohling Ret al., 2017, Intra-operative ultrasound-based augmented reality guidance for laparoscopic surgery, HEALTHCARE TECHNOLOGY LETTERS, Vol: 4, Pages: 204-209, ISSN: 2053-3713

Journal article

Camara M, Pratt P, Darzi A, Mayer Eet al., 2017, Simulation of Patient-Specific Deformable Ultrasound Imaging in Real Time, Lecture Notes in Computer Science, Vol: 10549, Pages: 11-18, ISSN: 0302-9743

Intraoperative ultrasound is an imaging modality frequently used to provide delineation of tissue boundaries. This paper proposes a simulation platform that enables rehearsal of patient-specific deformable ultrasound scanning in real-time, using preoperative CT as the data source. The simulation platform was implemented within the GPU-accelerated NVIDIA FleX position-based dynamics framework. The high-resolution particle model is used to deform both surface and volume meshes. The latter is used to compute the barycentric coordinates of each simulated ultrasound image pixel in the surrounding volume, which is then mapped back to the original undeformed CT volume. To validate the computation of simulated ultrasound images, a kidney phantom with an embedded tumour was CT-scanned in the rest position and at five different levels of probe-induced deformation. Measures of normalised cross-correlation and similarity between features were adopted to compare pairs of simulated and ground truth images. The accurate results demonstrate the potential of this approach for clinical translation.

Journal article

Zhang L, Ye M, Giannarou S, Pratt P, Yang GZet al., 2017, Motion-compensated autonomous scanning for tumour localisation using intraoperative ultrasound, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Vol: 10434, Pages: 619-627, ISSN: 0302-9743

Intraoperative ultrasound facilitates localisation of tumour boundaries during minimally invasive procedures. Autonomous ultrasound scanning systems have been recently proposed to improve scanning accuracy and reduce surgeons’ cognitive load. However, current methods mainly consider static scanning environments typically with the probe pressing against the tissue surface. In this work, a motion-compensated autonomous ultrasound scanning system using the da Vinci® Research Kit (dVRK) is proposed. An optimal scanning trajectory is generated considering both the tissue surface shape and the ultrasound transducer dimensions. An effective vision-based approach is proposed to learn the underlying tissue motion characteristics. The learned motion model is then incorporated into the visual servoing framework. The proposed system has been validated with both phantom and ex vivo experiments.

Journal article

Abeles A, Kwasnicki RM, Geoghegan L, Pratt P, Darzi Aet al., 2017, Wearable activity sensors: using physical activity to predict length of hospital stay?, International Congress of the Association-of-Surgeons-of-Great-Britain-and-Ireland, Publisher: Wiley, Pages: 53-53, ISSN: 1365-2168

Conference paper

Omar I, Dilley J, Pucher P, Pratt P, Ameen T, Vale J, Darzi A, Mayer Eet al., 2017, The robotix simulator: face and content validation using the fundamentals of robotic surgery (FRS) curriculum, Annual Meeting of the American-Urological-Association (AUA), Publisher: Elsevier, Pages: E700-E701, ISSN: 0022-5347

Conference paper

Tarunina M, Hernandez D, Kronsteiner-Dobramysl B, Pratt P, Watson T, Hua P, Gullo F, Van der Garde M, Zhang Y, Hook L, Choo Y, Watt Set al., 2016, A novel high throughput screening platform reveals an optimised cytokine formulation for human hematopoietic progenitor cell expansion, Stem Cells and Development, ISSN: 1557-8534

The main limitations of hematopoietic cord blood (CB) transplantation, viz. low cell dosage and delayed reconstitution, can be overcome by ex-vivo expansion. CB expansion under conventional culture causes the rapid cell differentiation and depletion of hematopoietic stem/progenitor cells (HSPC) responsible for engraftment. Here, we use combinatorial cell culture technology (CombiCult®) to identify media formulations that promote CD133+ CB HSPC proliferation while maintaining their phenotypic characteristics. We employed second generation CombiCult® screens that use electro-spraying technology to encapsulate CB cells in alginate beads. Our results suggest that, not only the combination, but also the order of addition of individual components has a profound influence on expansion of specific HSPC populations. Top protocols identified by the CombiCult® screen were used to culture human CD133+ CB HSPCs on nanofiber scaffolds and validate the expansion of the phenotypically defined CD34+CD38lo/-CD45RA-CD90+CD49f+ population of hematopoietic stem cells and their differentiation into defined progeny.

Journal article

Camara M, Mayer E, Darzi A, Pratt Pet al., 2016, Soft tissue deformation for surgical simulation: a position-based dynamics approach, International Journal of Computer Assisted Radiology and Surgery, Vol: 11, Pages: 919-928, ISSN: 1861-6410

Journal article

Di Marco AN, Jeyakumar J, Pratt PJ, Yang G-Z, Darzi AWet al., 2016, Evaluating a novel 3D stereoscopic visual display for transanal endoscopic surgery: a randomized controlled crossover study, Annals of Surgery, Vol: 263, Pages: 36-42, ISSN: 1528-1140

Journal article

Pratt P, Hughes-Hallett A, Zhang L, Patel N, Mayer E, Darzi A, Yang G-Zet al., 2015, Autonomous Ultrasound-Guided Tissue Dissection, 18th International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI), Publisher: SPRINGER INT PUBLISHING AG, Pages: 249-257, ISSN: 0302-9743

Intraoperative ultrasound imaging can act as a valuable guide during minimally invasive tumour resection. However, contemporaneous bimanual manipulation of the transducer and cutting instrument presents significant challenges for the surgeon. Both cannot occupy the same physical location, and so a carefully coordinated relative motion is required. Using robotic partial nephrectomy as an index procedure, and employing PVA cryogel tissue phantoms in a reduced dimensionality setting, this study sets out to achieve autonomous tissue dissection with a high velocity waterjet under ultrasound guidance. The open-source da Vinci Research Kit (DVRK) provides the foundation for a novel multimodal visual servoing approach, based on the simultaneous processing and analysis of endoscopic and ultrasound images. Following an accurate and robust Jacobian estimation procedure, dissections are performed with specified theoretical tumour margin distances. The resulting margins, with a mean difference of 0.77mm, indicate that the overall system performs accurately, and that future generalisation to 3D tumour and organ surface morphologies is warranted.

Conference paper

Gras G, Marcus HJ, Payne CJ, Pratt P, Yang GZet al., 2015, Visual Force Feedback for Hand-Held Microsurgical Instruments, Medical Image Computing and Computer-Assisted Intervention, ISSN: 0302-9743

Conference paper

Edgcumbe P, Pratt P, Yang G-Z, Nguan C, Rohling Ret al., 2015, Pico Lantern: Surface reconstruction and augmented reality in laparoscopic surgery using a pick-up laser projector, MEDICAL IMAGE ANALYSIS, Vol: 25, Pages: 95-102, ISSN: 1361-8415

Journal article

Pratt P, Jaeger A, Hughes-Hallett A, Mayer E, Vale J, Darzi A, Peters T, Yang G-Zet al., 2015, Robust ultrasound probe tracking: initial clinical experiences during robot-assisted partial nephrectomy, International Journal of Computer Assisted Radiology and Surgery, Vol: 10, Pages: 1905-1913, ISSN: 1861-6410

PurposeIn order to assist in the identification of renal vasculature and tumour boundaries in robot-assisted partial nephrectomy, robust ultrasound probe calibration and tracking methods are introduced. Contemporaneous image guidance during these crucial stages of the procedure should ultimately lead to improved safety and quality of outcome for the patient, through reduced positive margin rates, segmental clamping, shorter ischaemic times and nephron-sparing resection.MethodsSmall KeyDot markers with circular dot patterns are attached to a miniature pickup ultrasound probe. Generic probe calibration is superseded by a more robust scheme based on a sequence of physical transducer measurements. Motion prediction combined with a reduced region-of-interest in the endoscopic video feed facilitates real-time tracking and registration performance at full HD resolutions.ResultsQuantitative analysis confirms that circular dot patterns result in an improved translational and rotational working envelope, in comparison with the previous chessboard pattern implementation. Furthermore, increased robustness is observed with respect to prevailing illumination levels and out-of-focus images due to relatively small endoscopic depths of field.ConclusionCircular dot patterns should be employed in this context as they result in improved performance and robustness. This facilitates clinical usage and interpretation of the combined video and ultrasound overlay. The efficacy of the overall system is demonstrated in the first human clinical case.

Journal article

Marcus HJ, Pratt P, Hughes-Hallett A, Cundy TP, Marcus AP, Yang GZ, Darzi A, Nandi Det al., 2015, Comparative effectiveness and safety of image guidance systems in neurosurgery: a preclinical randomized study, Journal of Neurosurgery, Vol: 123, Pages: 307-313, ISSN: 1933-0693

OBJECT: Over the last decade, image guidance systems have been widely adopted in neurosurgery. Nonetheless, the evidence supporting the use of these systems in surgery remains limited. The aim of this study was to compare simultaneously the effectiveness and safety of various image guidance systems against that of standard surgery.METHODS: In this preclinical, randomized study, 50 novice surgeons were allocated to one of the following groups: 1) no image guidance, 2) triplanar display, 3) always-on solid overlay, 4) always-on wire mesh overlay, and 5) on-demand inverse realism overlay. Each participant was asked to identify a basilar tip aneurysm in a validated model head. The primary outcomes were time to task completion (in seconds) and tool path length (in mm). The secondary outcomes were recognition of an unexpected finding (i.e., a surgical clip) and subjective depth perception using a Likert scale.RESULTS: The time to task completion and tool path length were significantly lower when using any form of image guidance compared with no image guidance (p < 0.001 and p = 0.003, respectively). The tool path distance was also lower in groups using augmented reality compared with triplanar display (p = 0.010). Always-on solid overlay resulted in the greatest inattentional blindness (20% recognition of unexpected finding). Wire mesh and on-demand overlays mitigated, but did not negate, inattentional blindness and were comparable to triplanar display (40% recognition of unexpected finding in all groups). Wire mesh and inverse realism overlays also resulted in better subjective depth perception than always-on solid overlay (p = 0.031 and p = 0.008, respectively).CONCLUSIONS: New augmented reality platforms may improve performance in less-experienced surgeons. However, all image display modalities, including existing triplanar displays, carry a risk of inattentional blindness.

Journal article

King HK, Shang JS, Liu JL, Seneci CA, Wisanuvej PW, Giataganas PG, Patel NS, Clark JC, Vitiello VV, Bergeles CB, Pratt PP, Di Marco AD, Kerr KK, Darzi AD, Yang GZYet al., Micro-IGES Robot for Transanal Robotic Microsurgery., In The Hamlyn Symposium on Medical Robotics.

Conference paper

Hughes-Hallett A, Pratt P, Mayer E, Clark M, Vale J, Darzi Aet al., 2015, Using preoperative imaging for intraoperative guidance: a case of mistaken identity, International Journal of Medical Robotics and Computer Assisted Surgery, Vol: 12, Pages: 262-267, ISSN: 1478-596X

BACKGROUND: Surgical image guidance systems to date have tended to rely on reconstructions of preoperative datasets. This paper assesses the accuracy of these reconstructions to establish whether they are appropriate for use in image guidance platforms. METHODS: Nine raters (two experts in image interpretation and preparation, three in image interpretation, and four in neither interpretation nor preparation) were asked to perform a segmentation of ten renal tumours (four cystic and six solid tumours). These segmentations were compared with a gold standard consensus segmentation generated using a previously validated algorithm. RESULTS: Average sensitivity and positive predictive value (PPV) were 0.902 and 0.891, respectively. When assessing for variability between raters, significant differences were seen in the PPV, sensitivity and incursions and excursions from consensus tumour boundary. CONCLUSIONS: This paper has demonstrated that the interpretation required for the segmentation of preoperative imaging of renal tumours introduces significant inconsistency and inaccuracy. Copyright © 2015 John Wiley & Sons, Ltd.

Journal article

Marcus HJ, Pratt P, Hughes-Hallett A, Cundy TP, Marcus AP, Yang G-Z, Darzi A, Nandi Det al., 2015, Comparative effectiveness and safety of image guidance systems in surgery: a preclinical randomised study., Spring Meeting for Clinician Scientists in Training 2015, Publisher: Elsevier, Pages: S64-S64, ISSN: 0140-6736

BACKGROUND: Over the past decade image guidance systems have been widely adopted in specialties such as neurosurgery and otorhinolaryngology. Nonetheless, the evidence supporting the use of image guidance systems in surgery remains limited. New augmented reality systems offer the possibility of enhanced operating room workflow compared with existing triplanar image displays, but recent studies have highlighted several concerns, particularly the risk of inattentional blindness and impaired depth perception. The aim of this study was to compare simultaneously the effectiveness and safety of various image guidance systems against standard surgery. METHODS: In this preclinical randomised study design 50 novice surgeons were allocated to no image guidance, triplanar display, always-on solid overlay, always-on wire mesh overlay, or on-demand inverse realism overlay. Each participant was asked to identify a basilar tip aneurysm in a validated model head. The primary outcomes were time to task completion, and tool path length. The secondary outcomes were recognition of an unexpected finding (a surgical clip) and subjective depth perception (using a Likert scale). FINDINGS: Surgeons' time to task completion and tool path length were significantly lower in groups using any form of image guidance than in groups with no image guidance (p<0·001 and p=0·003, respectively). The tool path distance was also lower in groups using augmented reality than in those using triplanar display (p=0·010). Always-on solid overlay resulted in the greatest inattentional blindness (20% recognition of unexpected finding by all surgeons). Wire mesh and on-demand overlays mitigated but did not negate inattentional blindness, and were comparable with triplanar display (40% recognition of unexpected finding in all groups). Wire mesh and inverse realism overlays also resulted in better subjective depth perception than always-on solid overlay (p=0·031 and p=0·008, re

Conference paper

Hughes-Hallett A, Mayer EK, Pratt PJ, Vale JA, Darzi AWet al., 2015, Quantitative analysis of technological innovation in minimally invasive surgery, British Journal of Surgery, Vol: 102, Pages: e151-e157, ISSN: 1365-2168

BackgroundIn the past 30 years surgical practice has changed considerably owing to the advent of minimally invasive surgery (MIS). This paper investigates the changing surgical landscape chronologically and quantitatively, examining the technologies that have played, and are forecast to play, the largest part in this shift in surgical practice.MethodsElectronic patent and publication databases were searched over the interval 1980–2011 for (‘minimally invasive’ OR laparoscopic OR laparoscopy OR ‘minimal access’ OR ‘key hole’) AND (surgery OR surgical OR surgeon). The resulting patent codes were allocated into technology clusters. Technology clusters referred to repeatedly in the contemporary surgical literature were also included in the analysis. Growth curves of patents and publications for the resulting technology clusters were then plotted.ResultsThe initial search revealed 27 920 patents and 95 420 publications meeting the search criteria. The clusters meeting the criteria for in-depth analysis were: instruments, image guidance, surgical robotics, sutures, single-incision laparoscopic surgery (SILS) and natural-orifice transluminal endoscopic surgery (NOTES). Three patterns of growth were observed among these technology clusters: an S-shape (instruments and sutures), a gradual exponential rise (surgical robotics and image guidance), and a rapid contemporaneous exponential rise (NOTES and SILS).ConclusionTechnological innovation in MIS has been largely stagnant since its initial inception nearly 30 years ago, with few novel technologies emerging. The present study adds objective data to the previous claims that SILS, a surgical technique currently adopted by very few, represents an important part of the future of MIS.

Journal article

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