A Comparative Study of Three Systems for Liver Magnetic Resonance Elastography.

BACKGROUND: Different MR elastography (MRE) systems may produce different stiffness measurements, making direct comparison difficult in multi-center investigations. PURPOSE: To assess the repeatability and reproducibility of liver stiffness measured by three typical MRE systems. STUDY TYPE: Prospective. POPULATION/PHANTOMS: Thirty volunteers without liver disease history (20 males, aged 21-28)/5 gel phantoms. FIELD STRENGTH/SEQUENCE: 3.0 T United Imaging Healthcare (UIH), 1.5 T Siemens Healthcare, 3.0 T General Electric Healthcare (GE)/Echo planar imaging-based MRE sequence. ASSESSMENT: Wave images of volunteers and phantoms were acquired by three MRE systems. Tissue stiffness was evaluated by two observers, while phantom stiffness was assessed automatically by code. The reproducibility across three MRE systems was quantified based on the mean stiffness of each volunteer and phantom. STATISTICAL TESTS: Intraclass correlation coefficients (ICC), coefficients of variation (CV), and Bland-Altman analyses were used to assess the interobserver reproducibility, the interscan repeatability, and the intersystem reproducibility. Paired t-tests were performed to assess the interobserver and interscan variation. Friedman tests with Dunn's multiple comparison correction were performed to assess the intersystem variation. P values less than 0.05 indicated significant difference. RESULTS: The reproducibility of stiffness measured by the two observers demonstrated consistency with ICC > 0.92, CV < 4.32%, Mean bias < 2.23%, and P > 0.06. The repeatability of measurements obtained using the electromagnetic system for the liver revealed ICC > 0.96, CV < 3.86%, Mean bias < 0.19%, P > 0.90. When considering the range of reproducibility across the three systems for liver evaluations, results ranged with ICCs from 0.70 to 0.87, CVs from 6.46% to 10.99%, and Mean biases between 1.89% and 6.30%. Phantom studies showed similar results. The values of measured stiffness differed across all three systems significantly. DATA CONCLUSION: Liver stiffness values measured from different MRE systems can be different, but the measurements across the three MRE systems produced consistent results with excellent reproducibility. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Assessment of vibration modulated regional cerebral blood flow with MRI.

Human brain experiences vibration of certain magnitude and frequency during various physical activities such as vehicle transportation and machine operation, which may cause traumatic brain injury or other brain diseases. However, the mechanisms of brain pathogenesis due to vibration are not fully elucidated due to the lack of techniques to study brain functions while applying vibration to the brain at a specific magnitude and frequency. Here, this study reported a custom-built head-worn electromagnetic actuator that applied vibration to the brain in vivo at an accurate frequency inside a magnetic resonance imaging scanner while cerebral blood flow (CBF) was acquired. Using this technique, CBF values from 45 healthy volunteers were quantitatively measured immediately following vibration at 20, 30, 40 Hz, respectively. Results showed increasingly reduced CBF with increasing frequency at multiple regions of the brain, while the size of the regions expanded. Importantly, the vibration-induced CBF reduction regions largely fell inside the brain's default mode network (DMN), with about 58 or 46% overlap at 30 or 40 Hz, respectively. These findings demonstrate that vibration as a mechanical stimulus can change strain conditions, which may induce CBF reduction in the brain with regional differences in a frequency-dependent manner. Furthermore, the overlap between vibration-induced CBF reduction regions and DMN suggested a potential relationship between external mechanical stimuli and cognitive functions.

Microfluidic Approaches for Microactuators: From Fabrication, Actuation, to Functionalization.

Microactuators can autonomously convert external energy into specific mechanical motions. With the feature sizes varying from the micrometer to millimeter scale, microactuators offer many operation and control possibilities for miniaturized devices. In recent years, advanced microfluidic techniques have revolutionized the fabrication, actuation, and functionalization of microactuators. Microfluidics can not only facilitate fabrication with continuously changing materials but also deliver various signals to stimulate the microactuators as desired, and consequently improve microfluidic chips with multiple functions. Herein, this cross-field that systematically correlates microactuator properties and microfluidic functions is comprehensively reviewed. The fabrication strategies are classified into two types according to the flow state of the microfluids: stop-flow and continuous-flow prototyping. The working mechanism of microactuators in microfluidic chips is discussed in detail. Finally, the applications of microactuator-enriched functional chips, which include tunable imaging devices, micromanipulation tools, micromotors, and microsensors, are summarized. The existing challenges and future perspectives are also discussed. It is believed that with the rapid progress of this cutting-edge field, intelligent microsystems may realize high-throughput manipulation, characterization, and analysis of tiny objects and find broad applications in various fields, such as tissue engineering, micro/nanorobotics, and analytical devices.

Pleural effusion-based nomogram to predict outcomes in unselected patients with multiple myeloma: a large single center experience.

Pleural effusion (PE) is prevalent in unselected "real-life" populations of multiple myeloma (MM). However, its prognostic value on MM is currently elusive. This study aimed to explore the role of PE on MM prognosis and to develop a novel prognostic nomogram for a cohort of Chinese patients with MM. Patients diagnosed with MM form 2000 through 2017 were retrospectively enrolled. PE was evaluated by chest computed tomography (CT) scans. Independent predictors of overall survival (OS) were identified using a multivariable Cox regression model performed on variables selected by the least absolute shrinkage and selection operator (LASSO) algorithm. A nomogram was constructed based on these variables. The concordance index (C-index) and the calibration curve were used to evaluate the predictive performance of the nomogram. Among 861 patients analyzed, 368 patients developed PE. Multivariate cox regression and restricted mean survival time (RMST) analyses revealed that patients with PE experienced worse OS vs. patients without PE. A nomogram predictive of OS was constructed using PE, plasma cell proportion, international staging system (ISS) stage, Charlson comorbidity index (CCI), 1q21 gain, and autologous hematopoietic stem cell transplantation (HSCT). The nomogram showed satisfactory discrimination in the derivation cohort (C-index=0.729) and the validation cohort (C-index=0.684), outperforming the Durie-Salmon (DS) and ISS staging systems. Moreover, the nomogram accurately classified patients into two distinct high- and low-risk groups. PE is frequently encountered in the disease course for MM patients. We derivated and validated a novel nomogram for MM based on PE, outperforming the DS/ISS staging systems.

Frontiers of Medical Robotics: From Concept to Systems to Clinical Translation.

Medical robotics is poised to transform all aspects of medicine-from surgical intervention to targeted therapy, rehabilitation, and hospital automation. A key area is the development of robots for minimally invasive interventions. This review provides a detailed analysis of the evolution of interventional robots and discusses how the integration of imaging, sensing, and robotics can influence the patient care pathway toward precision intervention and patient-specific treatment. It outlines how closer coupling of perception, decision, and action can lead to enhanced dexterity, greater precision, and reduced invasiveness. It provides a critical analysis of some of the key interventional robot platforms developed over the years and their relative merit and intrinsic limitations. The review also presents a future outlook for robotic interventions and emerging trends in making them easier to use, lightweight, ergonomic, and intelligent, and thus smarter, safer, and more accessible for clinical use.

Role of Quantitative Computed Tomographic Scan Analysis in Lung Volume Reduction for Emphysema.

Recent advances in bronchoscopic lung volume reduction (BLVR) offer new therapeutic alternatives for patients with emphysema and hyperinflation. Endobronchial valves and coils are 2 potential BLVR techniques which have been shown to improve pulmonary function and the quality of life in patients with emphysema. Current patient selection for LVR procedures relies on 3 main inclusion criteria: low attenuation area (in %), also known as emphysema score, heterogeneity score, and fissure integrity score. Volumetric analysis in combination with densitometric analysis of the affected lung lobe or segment with quantitative CT to determine emphysema severity play an important role in treatment planning and post-operative assessment. Due to the variations in lung anatomy, manual corrections are often required to ensure successful and accurate lobe segmentation for pathological and post-treatment CT scan analysis. The advanced development and utilisation of quantitative CT do not simply represent regional changes in pulmonary function but aids in analysis for better patient selection with severe emphysema who are most likely to benefit from BLVR.

Quantitative Evaluation of Lobar Pulmonary Function of Emphysema Patients with Endobronchial Coils.

BACKGROUND: Recent advances in bronchoscopic lung volume reduction offer new therapies for patients with emphysema and hyperinflation. Pulmonary lobe segmentation with quantification of lobar volumes and emphysema severity plays a pivotal role in treatment planning and post-interventional assessment. Computed tomography (CT)-derived lobar volumes could reflect more accurate regional changes in pulmonary function. OBJECTIVES: The aim of our study is to validate the reliability of an in-house CT Lung Segmentation software (LungSeg; the Hamlyn Centre, Imperial College London, UK) for lung lobar volume and emphysema quantification for chronic obstructive pulmonary disease (COPD) patients. METHODS: A total of 108 CT scans from subjects who participated in an endobronchial coil treatment trial were included. Lobar volume and emphysema quantification were performed using the LungSeg and Syngo CT Pulmo 3D package (Siemens Healthcare GmbH, Germany). The inter-user reliability of the LungSeg program was investigated. Correlation coefficients and Bland-Altman analyses were used to quantify the inter-software variability. The agreement between CT volume analysis and plethysmography analysis was also examined. RESULTS: The high intraclass correlation coefficients (mean ICC = 0.98) of the lobar volumes and emphysema indices measured by LungSeg suggest its excellent reproducibility. The LungSeg and Syngo program have good correlation (rho ≥0.94) and agreement for both lobar volume (median difference = 94 mL and LOAnp = 214.6 mL) and emphysema index (median difference ≤1.5% and LOAnp ≤2.03%) calculations. CT analysis provides a higher estimation of total lung capacity (TLCCT) than body plethysmography (TLCpleth), while there is a fair agreement on residual volume (RVCT) by LungSeg as compared with body plethysmography (RVpleth). CONCLUSIONS: CT-derived lobar volume and emphysema quantification using the LungSeg program is efficient and reliable in allowing lobar volume assessment. LungSeg has low inter-user variability and agrees better with plethysmography for COPD assessment in our study.

Temporal Stress in the Operating Room: Brain Engagement Promotes "Coping" and Disengagement Prompts "Choking".

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 ±â€ŠSD: PGY1-2: SP = 160.3 ±â€Š24.8 vs TP = 202.1 ±â€Š45.4, P < 0.001; PGY3-4: SP = 123.0 ±â€Š52.0 vs TP = 172.5 ±â€Š43.1, P < 0.01; PGY5: SP = 105.8 ±â€Š55.3 vs TP = 159.1 ±â€Š63.1, 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, enhance task engagement, and improve performance under pressure.

A Monolithic Force-Sensitive 3D Microgripper Fabricated on the Tip of an Optical Fiber Using 2-Photon Polymerization.

Microscale robotic devices have myriad potential applications including drug delivery, biosensing, cell manipulation, and microsurgery. In this work, a tethered, 3D, compliant grasper with an integrated force sensor is presented, the entirety of which is fabricated on the tip of an optical fiber in a single-step process using 2-photon polymerization. This gripper can prove useful for the interrogation of biological microstructures such as alveoli, villi, or even individual cells. The position of the passively actuated grasper is controlled via micromanipulation of the optical fiber, and the microrobotic device measures approximately 100 µm in length and breadth. The force estimation is achieved using optical interferometry: high-dimensional spectral readings are used to train artificial neural networks to predict the axial force exerted on/by the gripper. The design, characterization, and testing of the grasper are described and its real-time force-sensing capability with an accuracy below 2.7% of the maximum calibrated force is demonstrated.

Micro-scale fiber-optic force sensor fabricated using direct laser writing and calibrated using machine learning.

Fiber-optic sensors have numerous existing and emerging applications spanning areas from industrial process monitoring to medical diagnosis. Two of the most common fiber sensors are based on the fabrication of Bragg gratings or Fabry-Perot etalons. While these techniques offer a large array of sensing targets, their utility can be limited by the difficulties involved in fabricating forward viewing probes (Bragg gratings) and in obtaining sufficient signal-to-noise ratios (Fabry-Perot systems). In this article we present a micro-scale fiber-optic force sensor produced using direct laser writing (DLW). The fabrication entails a single-step process that can be undertaken in a reliable and repeatable manner using a commercial DLW system. The sensor is made of a series of thin plates (i.e. Fabry-Perot etalons), which are supported by springs that compress under an applied force. At the proximal end of the fiber, the interferometric changes that are induced as the sensor is compressed are read out using reflectance spectroscopy, and the resulting spectral changes are calibrated with respect to applied force. This calibration is performed using either singular value decomposition (SVD) followed by linear regression or artificial neural networks. We describe the design and optimization of this device, with a particular focus on the data analysis required for calibration. Finally, we demonstrate proof-of-concept force sensing over the range 0-50 µN, with a measurement error of approximately 1.5 µN.

An Intraoperative Visualization System Using Hyperspectral Imaging to Aid in Brain Tumor Delineation.

Hyperspectral imaging (HSI) allows for the acquisition of large numbers of spectral bands throughout the electromagnetic spectrum (within and beyond the visual range) with respect to the surface of scenes captured by sensors. Using this information and a set of complex classification algorithms, it is possible to determine which material or substance is located in each pixel. The work presented in this paper aims to exploit the characteristics of HSI to develop a demonstrator capable of delineating tumor tissue from brain tissue during neurosurgical operations. Improved delineation of tumor boundaries is expected to improve the results of surgery. The developed demonstrator is composed of two hyperspectral cameras covering a spectral range of 400-1700 nm. Furthermore, a hardware accelerator connected to a control unit is used to speed up the hyperspectral brain cancer detection algorithm to achieve processing during the time of surgery. A labeled dataset comprised of more than 300,000 spectral signatures is used as the training dataset for the supervised stage of the classification algorithm. In this preliminary study, thematic maps obtained from a validation database of seven hyperspectral images of in vivo brain tissue captured and processed during neurosurgical operations demonstrate that the system is able to discriminate between normal and tumor tissue in the brain. The results can be provided during the surgical procedure (~1 min), making it a practical system for neurosurgeons to use in the near future to improve excision and potentially improve patient outcomes.

Isolation, Structural Elucidation of Three New Triterpenoids from the Stems and Leaves of Schisandra chinensis (Turcz) Baill.

Schisandra chinensis (Turcz) Baill. is sufficiently well known as a medicinal plant worldwide, which modern research shows has many pharmacological activities such as hepatoprotective, anti-inflammatory effect, potent anti-HIV-1 activity, anti-tumor effect, and activity on the central nervous system. With considerable chemical investigation, three new triterpenoids (1⁻3), together with four known triterpenoids were isolated from the S. chinensis (Turcz) Baill. Their structures were elucidated by 1D- and 2D-NMR spectroscopic analyses, single-crystal X-ray diffraction and high-resolution mass spectroscopy, which were identified as Schisanlactone I (1), Schinalactone D, (2), Schisanlactone J, (3) Kadsuphilactone B (4), Schisanlactone C (5), Schisphendilactone B (6), and Schinchinenlactone A (7). The cytotoxicity of those compounds (1⁻7) was tested against Hep-G2 cell lines, but no apparent antitumor activity was observed at 50 µg/mL using MTT method.

"Contemplating the Next Maneuver": Functional Neuroimaging Reveals Intraoperative Decision-making Strategies.

OBJECTIVE: To investigate differences in the quality, confidence, and consistency of intraoperative surgical decision making (DM) and using functional neuroimaging expose decision systems that operators use. SUMMARY BACKGROUND DATA: Novices are hypothesized to use conscious analysis (effortful DM) leading to activation across the dorsolateral prefrontal cortex, whereas experts are expected to use unconscious automation (habitual DM) in which decisions are recognition-primed and prefrontal cortex independent. METHODS: A total of 22 subjects (10 medical student novices, 7 residents, and 5 attendings) reviewed simulated laparoscopic cholecystectomy videos, determined the next safest operative maneuver upon video termination (10 s), and reported decision confidence. Video paradigms either declared ("primed") or withheld ("unprimed") the next operative maneuver. Simultaneously, changes in cortical oxygenated hemoglobin and deoxygenated hemoglobin inferring prefrontal activation were recorded using Optical Topography. Decision confidence, consistency (primed vs unprimed), and quality (script concordance) were assessed. RESULTS: Attendings and residents were significantly more certain (P < 0.001), and decision quality was superior (script concordance: attendings = 90%, residents = 78.3%, and novices = 53.3%). Decision consistency was significantly superior in experts (P < 0.001) and residents (P < 0.05) than novices (P = 0.183). During unprimed DM, novices showed significant activation of the dorsolateral prefrontal cortex, whereas this activation pattern was not observed among residents and attendings. During primed DM, significant activation was not observed in any group. CONCLUSIONS: Expert DM is characterized by improved quality, consistency, and confidence. The findings imply attendings use a habitual decision system, whereas novices use an effortful approach under uncertainty. In the presence of operative cues (primes), novices disengage the prefrontal cortex and seem to accept the observed operative decision as correct.

Clinical Correlation between Real-Time Endocytoscopy, Confocal Endomicroscopy, and Histopathology in the Central Airways.

BACKGROUND: Lung cancer is one of the commonest malignancies with a worldwide incidence of 1.6 million cases each year. Although the main aetiological factor has been identified (cigarette smoking), the progression of lung cancer from early changes such as dysplasia through to cancer is still not fully understood. Furthermore, current research techniques are reliant on obtaining tissue biopsies, a process that alters the natural history of the very process under investigation. Hence, there is a need for developing optical biopsy techniques. OBJECTIVES: To prospectively evaluate the feasibility of endocytoscopy and confocal endomicroscopy in the detection of malignant and pre-malignant changes in the airways. METHODS: Findings with endocytoscopy and endomicroscopy were compared with conventional biopsies obtained from the same areas in 25 patients undergoing bronchoscopy for evaluation of endobronchial abnormalities and in 5 healthy control subjects. RESULTS: Endocytoscopy was technically more difficult, and interpretable images were only obtained in 21 of the patients evaluated, and hence, complete information including histopathological information was available in 21 patients. Endocytoscopy appeared to correlate with the histopathological findings on tissue biopsy, and was able to distinguish normal epithelium from dysplasia and carcinoma. Confocal endomicroscopy was a more reliable technique with adequate visual information obtained in all patients examined but was unable to distinguish between dysplasia and carcinoma. CONCLUSION: This feasibility study suggests that endocytoscopy may have the potential to fulfil the role of optical biopsy in the evaluation of the pathogenesis of lung cancer.

The role of technology in minimally invasive surgery: state of the art, recent developments and future directions.

The diffusion of minimally invasive surgery has thrived in recent years, providing substantial benefits over traditional techniques for a number of surgical interventions. This rapid growth has been possible due to significant advancements in medical technology, which partly solved some of the technical and clinical challenges associated with minimally invasive techniques. The issues that still limit its widespread adoption for some applications include the limited field of view; reduced manoeuvrability of the tools; lack of haptic feedback; loss of depth perception; extended learning curve; prolonged operative times and higher financial costs. The present review discusses some of the main recent technological advancements that fuelled the uptake of minimally invasive surgery, focussing especially on the areas of imaging, instrumentation, cameras and robotics. The current limitations of state-of-the-art technology are identified and addressed, proposing future research directions necessary to overcome them.

Developing Fine-Grained Actigraphies for Rheumatoid Arthritis Patients from a Single Accelerometer Using Machine Learning.

In addition to routine clinical examination, unobtrusive and physical monitoring of Rheumatoid Arthritis (RA) patients provides an important source of information to enable understanding the impact of the disease on quality of life. Besides an increase in sedentary behaviour, pain in RA can negatively impact simple physical activities such as getting out of bed and standing up from a chair. The objective of this work is to develop a method that can generate fine-grained actigraphies to capture the impact of the disease on the daily activities of patients. A processing methodology is presented to automatically tag activity accelerometer data from a cohort of moderate-to-severe RA patients. A study of procesing methods based on machine learning and deep learning is provided. Thirty subjects, 10 RA patients and 20 healthy control subjects, were recruited in the study. A single tri-axial accelerometer was attached to the position of the fifth lumbar vertebra (L5) of each subject with a tag prediction granularity of 3 s. The proposed method is capable of handling unbalanced datasets from tagged data while accounting for long-duration activities such as sitting and lying, as well as short transitions such as sit-to-stand or lying-to-sit. The methodology also includes a novel mechanism for automatically applying a threshold to predictions by their confidence levels, in addition to a logical filter to correct for infeasible sequences of activities. Performance tests showed that the method was able to achieve around 95% accuracy and 81% F-score. The produced actigraphies can be helpful to generate objective RA disease-specific markers of patient mobility in-between clinical site visits.

Making the Leap: the Translation of Innovative Surgical Devices From the Laboratory to the Operating Room.

OBJECTIVE: To determine the rate and extent of translation of innovative surgical devices from the laboratory to first-in-human studies, and to evaluate the factors influencing such translation. SUMMARY BACKGROUND DATA: Innovative surgical devices have preceded many of the major advances in surgical practice. However, the process by which devices arising from academia find their way to translation remains poorly understood. METHODS: All biomedical engineering journals, and the 5 basic science journals with the highest impact factor, were searched between January 1993 and January 2000 using the Boolean search term "surgery OR surgeon OR surgical". Articles were included if they described the development of a new device and a surgical application was described. A recursive search of all citations to the article was performed using the Web of Science (Thompson-Reuters, New York, NY) to identify any associated first-in-human studies published by January 2015. Kaplan-Meier curves were constructed for the time to first-in-human studies. Factors influencing translation were evaluated using log-rank and Cox proportional hazards models. RESULTS: A total of 8297 articles were screened, and 205 publications describing unique devices were identified. The probability of a first-in-human at 10 years was 9.8%. Clinical involvement was a significant predictor of a first-in-human study (P = 0.02); devices developed with early clinical collaboration were over 6 times more likely to be translated than those without [RR 6.5 (95% confidence interval 0.9-48)]. CONCLUSIONS: These findings support initiatives to increase clinical translation through improved interactions between basic, translational, and clinical researchers.

Evaluating a Novel 3D Stereoscopic Visual Display for Transanal Endoscopic Surgery: A Randomized Controlled Crossover Study.

OBJECTIVE: To compare surgical performance with transanal endoscopic surgery (TES) using a novel 3-dimensional (3D) stereoscopic viewer against the current modalities of a 3D stereoendoscope, 3D, and 2-dimensional (2D) high-definition monitors. BACKGROUND: TES is accepted as the primary treatment for selected rectal tumors. Current TES systems offer a 2D monitor, or 3D image, viewed directly via a stereoendoscope, necessitating an uncomfortable operating position. To address this and provide a platform for future image augmentation, a 3D stereoscopic display was created. METHODS: Forty participants, of mixed experience level, completed a simulated TES task using 4 visual displays (novel stereoscopic viewer and currently utilized stereoendoscope, 3D, and 2D high-definition monitors) in a randomly allocated order. Primary outcome measures were: time taken, path length, and accuracy. Secondary outcomes were: task workload and participant questionnaire results. RESULTS: Median time taken and path length were significantly shorter for the novel viewer versus 2D and 3D, and not significantly different to the traditional stereoendoscope. Significant differences were found in accuracy, task workload, and questionnaire assessment in favor of the novel viewer, as compared to all 3 modalities. CONCLUSIONS: This novel 3D stereoscopic viewer allows surgical performance in TES equivalent to that achieved using the current stereoendoscope and superior to standard 2D and 3D displays, but with lower physical and mental demands for the surgeon. Participants expressed a preference for this system, ranking it more highly on a questionnaire. Clinical translation of this work has begun with the novel viewer being used in 5 TES patients.

Comparative effectiveness and safety of image guidance systems in surgery: a preclinical randomised study.

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, respectively). INTERPRETATION: This study suggests that new augmented reality platforms incorporating always-on wire mesh and on-demand inverse realism might improve surgical performance, at least in novice surgeons. All image display modalities, including existing triplanar display, carry a risk of inattentional blindness. FUNDING: Wellcome Trust.

Reducing contact forces in the arch and supra-aortic vessels using the Magellan robot.

OBJECTIVE: Conventional catheter manipulation in the arch and supra-aortic trunks carries a risk of cerebral embolization. This study proposes a platform for detailed quantitative analysis of contact forces (CF) exerted on the vasculature, in order to investigate the potential advantages of robotic navigation. METHODS: An anthropomorphic phantom representing a type I bovine arch was mounted and coupled onto a force/torque sensor. Three-axis force readings provided an average root-mean-square modulus, indicating the total forces exerted on the phantom. Each of the left subclavian, left common carotid, and right common carotid arteries was cannulated within a simulated endovascular suite with conventional (n = 42) vs robotic techniques (n = 30) by two operator groups: experts and novices. The procedure path was divided into three phases, and performance metrics corresponding to mean and maximum forces, force impact over time, standard deviation of forces, and number of significant catheter contacts with the arterial wall were extracted. RESULTS: Overall, median CF were reduced from 1.20 N (interquartile range [IQR], 0.98-1.56 N) to 0.31 N (IQR, 0.26-0.40 N; P < .001) for the right common carotid artery; 1.59 N (IQR, 1.11-1.85 N) to 0.33 N (IQR, 0.29-0.43 N; P < .001) for the left common carotid artery; and 0.84 N (IQR, 0.47-1.08 N) to 0.10 N (IQR, 0.07-0.17 N; P < .001) for the left subclavian artery. Robotic navigation resulted in significant reductions for the mean and maximum forces for each procedural phase. Significant improvements were also seen in other metrics, particularly at the target vessel ostium and for the more anatomically challenging procedural phases. Force reductions using robotic technology were evident for both novice and expert groups. CONCLUSIONS: Robotic navigation can potentially reduce CF and catheter-tissue contact points in an in vitro model, by enhancing catheter stability and control during endovascular manipulation.