Visceral-to-subcutaneous fat ratio exhibits strongest association with early post-operative outcomes in patients undergoing surgery for advanced rectal cancer.

AIM: Despite their promise as prognostic factors in colorectal cancer, anthropometric data are frequently contradictory or difficult to interpret, with single body-composition parameters often investigated in isolation or heterogeneous clinical cohorts used in analyses. We sought to assess a spectrum of body-composition parameters in a highly selected cohort with locally advanced rectal cancer in a bid to determine those with strongest prognostic potential in this specific setting. MATERIALS/METHODS: Between 2014 and 2020, 78 individuals received neoadjuvant chemotherapy, or chemoradiotherapy, followed by radical surgery in the treatment of locally advanced rectal adenocarcinoma at Oxford University Hospitals Trust. Demographic, treatment-related, perioperative, and short-term outcomes data were assessed. Body-composition parameters included BMI, and those derived from pre-operative computed-tomography imaging: skeletal mass index (SMI), visceral fat area (VFA), subcutaneous fat area (SFA), perinephric fat area (PFA) visceral-to-subcutaneous fat ratio (V/S), sarcopenia, and sarcopenic obesity (SO). RESULTS: Pre-operative body-composition parameters exhibited particularly strong correlation with post-operative outcomes, with VFA (p = 0.002), V/S (p = 0.019), SO (p = 0.012), and PFA (p = 0.0016) all associated with an increased length of hospital stay. Univariate and multivariate analyses demonstrated V/S to be the sole independent body-composition risk factor to be associated with an increased risk of developing Clavien-Dindo complications ≥ 2 (p = 0.033) as well as an increased length of stay (p = 0.005). CONCLUSION: Among patients with locally advanced rectal cancer, high visceral-to-subcutaneous fat ratio is the body-composition parameter most strongly associated with poor early post-operative outcomes. This should be considered in patient selection and prehabilitation protocols. WHAT DOES THIS PAPER ADD TO THE LITERATURE? : Our study demonstrates that among body composition parameters, high visceral-to-subcutaneous fat ratio is strongly associated with increased risk of post-operative complications and increased length of stay in patients undergoing surgery for advanced rectal cancer.

Imperial College near infrared spectroscopy neuroimaging analysis framework.

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.

The impact of expert visual guidance on trainee visual search strategy, visual attention and motor skills.

Minimally invasive and robotic surgery changes the capacity for surgical mentors to guide their trainees with the control customary to open surgery. This neuroergonomic study aims to assess a "Collaborative Gaze Channel" (CGC); which detects trainer gaze-behavior and displays the point of regard to the trainee. A randomized crossover study was conducted in which twenty subjects performed a simulated robotic surgical task necessitating collaboration either with verbal (control condition) or visual guidance with CGC (study condition). Trainee occipito-parietal (O-P) cortical function was assessed with optical topography (OT) and gaze-behavior was evaluated using video-oculography. Performance during gaze-assistance was significantly superior [biopsy number: (mean ± SD): control = 5.6 ± 1.8 vs. CGC = 6.6 ± 2.0; p < 0.05] and was associated with significantly lower O-P cortical activity [ΔHbO2 mMol × cm [median (IQR)] control = 2.5 (12.0) vs. CGC 0.63 (11.2), p < 0.001]. A random effect model (REM) confirmed the association between guidance mode and O-P excitation. Network cost and global efficiency were not significantly influenced by guidance mode. A gaze channel enhances performance, modulates visual search, and alleviates the burden in brain centers subserving visual attention and does not induce changes in the trainee's O-P functional network observable with the current OT technique. The results imply that through visual guidance, attentional resources may be liberated, potentially improving the capability of trainees to attend to other safety critical events during the procedure.

Enhanced frontoparietal network architectures following "gaze-contingent" versus "free-hand" motor learning.

Longitudinal changes in cortical function are known to accompany motor skills learning, and can be detected as an evolution in the activation map. These changes include attenuation in activation in the prefrontal cortex and increased activation in primary and secondary motor regions, the cerebellum and posterior parietal cortex. Despite this, comparatively little is known regarding the impact of the mode or type of training on the speed of activation map plasticity and on longitudinal variation in network architectures. To address this, we randomised twenty-one subjects to learn a complex motor tracking task delivered across six practice sessions in either "free-hand" or "gaze-contingent motor control" mode, during which frontoparietal cortical function was evaluated using functional near infrared spectroscopy. Results demonstrate that upon practice termination, gaze-assisted learners had achieved superior technical performance compared to free-hand learners. Furthermore, evolution in frontoparietal activation foci indicative of expertise was achieved at an earlier stage in practice amongst gaze-assisted learners. Both groups exhibited economical small world topology; however, networks in learners randomised to gaze-assistance were less costly and showed higher values of local efficiency suggesting improved frontoparietal communication in this group. We conclude that the benefits of gaze-assisted motor learning are evidenced by improved technical accuracy, more rapid task internalisation and greater neuronal efficiency. This form of assisted motor learning may have occupational relevance for high precision control such as in surgery or following re-learning as part of stroke rehabilitation.

Multispectral image alignment using a three channel endoscope in vivo during minimally invasive surgery.

Sequential multispectral imaging is an acquisition technique that involves collecting images of a target at different wavelengths, to compile a spectrum for each pixel. In surgical applications it suffers from low illumination levels and motion artefacts. A three-channel rigid endoscope system has been developed that allows simultaneous recording of stereoscopic and multispectral images. Salient features on the tissue surface may be tracked during the acquisition in the stereo cameras and, using multiple camera triangulation techniques, this information used to align the multispectral images automatically even though the tissue or camera is moving. This paper describes a detailed validation of the set-up in a controlled experiment before presenting the first in vivo use of the device in a porcine minimally invasive surgical procedure. Multispectral images of the large bowel were acquired and used to extract the relative concentration of haemoglobin in the tissue despite motion due to breathing during the acquisition. Using the stereoscopic information it was also possible to overlay the multispectral information on the reconstructed 3D surface. This experiment demonstrates the ability of this system for measuring blood perfusion changes in the tissue during surgery and its potential use as a platform for other sequential imaging modalities.

The feasibility, safety and outcomes of laparoscopic re-operation for achalasia.

INTRODUCTION: Heller myotomy for achalasia is associated with a recurrence rate of around 10%, thus reoperative surgery is often necessitated. This paper aims to review the available literature on laparoscopic reoperation for achalasia in order to assess its feasibility and effectiveness. MATERIAL & METHODS: A Medline, Embase, Ovid, Cochrane database and Google(TM) Scholar search was performed with the following Mesh terms: "laparoscopic", "redo", "reoperative", "Heller's", "esophagomyotomy" and "achalasia". Outcomes of interest included patient demographics and details of primary procedure, operative details, intra- and post operative complications and symptom scores. RESULTS: Seven studies reported outcomes from 54 cases. Conversion occurred in 7% (4/54) of cases. Thirteen percent (7/54) of patients sustained intra-operative gastric or oesophageal perforation; however these were all noted and repaired intra-operatively leading to no subsequent morbidity. No deaths were reported. Pre- and post operative symptom scores were heterogeneous, however did appear to improve after the procedure. DISCUSSION: This review demonstrates that laparoscopic reoperation for achalasia is feasible and safe with complication rates comparable to the primary laparoscopic operation. It is recommended that laparoscopic reoperative Heller's myotomy should only be performed by surgeons with special interest in oesophagogastric surgery and adequate experience in laparoscopic surgery for achalasia.

Collaborative gaze channelling for improved cooperation during robotic assisted surgery.

The use of multiple robots for performing complex tasks is becoming a common practice for many robot applications. When different operators are involved, effective cooperation with anticipated manoeuvres is important for seamless, synergistic control of all the end-effectors. In this paper, the concept of Collaborative Gaze Channelling (CGC) is presented for improved control of surgical robots for a shared task. Through eye tracking, the fixations of each operator are monitored and presented in a shared surgical workspace. CGC permits remote or physically separated collaborators to share their intention by visualising the eye gaze of their counterparts, and thus recovers, to a certain extent, the information of mutual intent that we rely upon in a vis-à-vis working setting. In this study, the efficiency of surgical manipulation with and without CGC for controlling a pair of bimanual surgical robots is evaluated by analysing the level of coordination of two independent operators. Fitts' law is used to compare the quality of movement with or without CGC. A total of 40 subjects have been recruited for this study and the results show that the proposed CGC framework exhibits significant improvement (p < 0.05) on all the motion indices used for quality assessment. This study demonstrates that visual guidance is an implicit yet effective way of communication during collaborative tasks for robotic surgery. Detailed experimental validation results demonstrate the potential clinical value of the proposed CGC framework.

Gaze-Contingent Motor Channelling, haptic constraints and associated cognitive demand for robotic MIS.

The success of MIS is coupled with an increasing demand on surgeons' manual dexterity and visuomotor coordination due to the complexity of instrument manipulations. The use of master-slave surgical robots has avoided many of the drawbacks of MIS, but at the same time, has increased the physical separation between the surgeon and the patient. Tissue deformation combined with restricted workspace and visibility of an already cluttered environment can raise critical issues related to surgical precision and safety. Reconnecting the essential visuomotor sensory feedback is important for the safe practice of robot-assisted MIS procedures. This paper introduces a novel gaze-contingent framework for real-time haptic feedback and virtual fixtures by transforming visual sensory information into physical constraints that can interact with the motor sensory channel. We demonstrate how motor tracking of deforming tissue can be made more effective and accurate through the concept of Gaze-Contingent Motor Channelling. The method is also extended to 3D by introducing the concept of Gaze-Contingent Haptic Constraints where eye gaze is used to dynamically prescribe and update safety boundaries during robot-assisted MIS without prior knowledge of the soft-tissue morphology. Initial validation results on both simulated and robot assisted phantom procedures demonstrate the potential clinical value of the technique. In order to assess the associated cognitive demand of the proposed concepts, functional Near-Infrared Spectroscopy is used and preliminary results are discussed.

Disinfection of the Access Orifice in NOTES: Evaluation of the Evidence Base.

Introduction. Appropriate prevention of infection is a key area of research in natural orifice translumenal endoscopic surgery (NOTES), as identified by the Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR). Methods. A review of the literature was conducted evaluating the evidence base for access orifice preparation/treatment in NOTES procedures in the context of infectious complications. Recommendations based on the Oxford Centre for Evidence-Based Medicine guidelines were made. Results. The most robust evidence includes several experimental randomised controlled trials assessing infectious complications in the transgastric approach to NOTES. Transvaginal procedures are long established for accessing the peritoneal cavity following disinfection with antiseptic. Only experimental case series for transcolonic and transvesical approaches are described. Conclusion. Grade C recommendation requiring no preoperative preparation can be made for the transgastric approach. Antiseptic irrigation is recommended for transvaginal (grade C) NOTES access, as is current practice. Further human trials need to be conducted to corroborate the current evidence base for transgastric closure. It is important that future trials are conducted in a methodologically robust fashion, with emphasis on clinical outcomes and standardisation of enterotomy closure and postoperative therapy.

Transgastric or trans-sigmoidal? The impact of the choice of access on task performance in target natural orifice translumenal endoscopic surgery procedures.

INTRODUCTION: The effect of the choice of access upon endoscope control during a navigational task is explored within a simulator model. MATERIALS AND METHODS: The study was conducted within the endoscopic-laparoscopic interdisciplinary training entity (ELITE) model (Minimally Invasive Therapy and Intervention Research Group [MITI], Technische Universität, Germany)--a validated natural orifice translumenal endoscopic surgery (NOTES) simulator. Seventeen subjects, 15 with no endoscopic experience, navigated the endoscope from predefined trans-sigmoidal and transgastric access points to the appendix and the gallbladder. A previously defined and validated quantitative analysis of endoscope control, in addition to time taken to complete the task, was used to evaluate overall performance. The quantitative analysis extrapolated the movements of the subject's wrist in control of the endoscope and rated the movements using a scoring system of 0-3 based upon the smoothness of the movements recorded. RESULTS: Although no significant difference in terms of performance time was demonstrated between the two approaches to the appendix (36.6 ± 14.7 seconds TG and 29.8 ± 16 seconds TS) (P = .214), when the endoscope control score was compared, a significant difference was confirmed (3 TG and 7 TS) (P < .001). With regard to the approach to the gallbladder, a significant difference in terms of both the performance time (19.8 seconds TG and 35.6 seconds TS) (P < .001) and the quality of endoscope control (7 TG and 5 TS) (P = .001) was demonstrated. CONCLUSION: The choice of access route impacts directly on the ease with which the endoscopist navigates to the target. Within this study, the trans-sigmoidal appears the most appropriate to access the appendix and the transgastric for the gallbladder.

The ergonomics of natural orifice translumenal endoscopic surgery (NOTES) navigation in terms of performance, stress, and cognitive behavior.

BACKGROUND: The evolution toward minimally invasive surgery and subsequently to natural orifice translumenal endoscopic surgery (NOTES) poses challenges to the surgeon in terms of increased task complexity requiring greater visuospatial and navigational ability. Neuroergonomics is the study of the brain and behavior at work, and establishing the baseline cortical response for NOTES procedures will help to ascertain whether technological innovation such as navigational aids can alleviate the task-induced cognitive burden. The aims of the current study are to characterize the impact of navigation within a NOTES environment on the subject in terms of (1) performance, (2) stress, (3) prefrontal cortical activity, and (4) how this is influenced by expertise. METHODS: In all, 29 subjects were assessed for performance, stress response, and prefrontal cortical activity during a NOTES navigational task within a validated NOTES simulator. RESULTS: Experts performed significantly better than novices (P < .05). Expertise was not a predictor for overall changes in prefrontal cortical activity. The differences between experts and novices were modulated by the location of prefrontal cortical activity, with experts demonstrating more pronounced lateral prefrontal cortical activation compared with novices. Stress was not an independent predictor of changes in prefrontal cortical hemodynamics. CONCLUSION: This study is the first to characterize the performance, stress, and neurocognitive behavior associated with natural orifice translumenal endoscopic surgery navigation. The results indicate the relevance of visuospatial centers in successful task execution, and they serve as a baseline within the neuroergonomic paradigm for investigating performance-enhancing technology.

Cognitive burden estimation for visuomotor learning with fNIRS.

Novel robotic technologies utilised in surgery need assessment for their effects on the user as well as on technical performance. In this paper, the evolution in 'cognitive burden' across visuomotor learning is quantified using a combination of functional near infrared spectroscopy (fNIRS) and graph theory. The results demonstrate escalating costs within the activated cortical network during the intermediate phase of learning which is manifest as an increase in cognitive burden. This innovative application of graph theory and fNIRS enables the economic evaluation of brain behaviour underpinning task execution and how this may be impacted by novel technology and learning. Consequently, this may shed light on how robotic technologies improve human-machine interaction and augment minimally invasive surgical skills acquisition. This work has significant implications for the development and assessment of emergent robotic technologies at cortical level and in elucidating learning-related plasticity in terms of inter-regional cortical connectivity.

Perceptually Docked Control Environment for Multiple Microbots: Application to the Gastric Wall Biopsy.

This paper presents a human-robot interface with perceptual docking to allow for the control of multiple microbots. The aim is to demonstrate that real-time eye tracking can be used for empowering robots with human vision by using knowledge acquired in situ. Several micro-robots can be directly controlled through a combination of manual and eye control. The novel control environment is demonstrated on a virtual biopsy of gastric lesion through an endoluminal approach. Twenty-one subjects were recruited to test the control environment. Statistical analysis was conducted on the completion time of the task using the keyboard control and the proposed eye tracking framework. System integration with the concept of perceptual docking framework demonstrated statistically significant improvement of task execution.

Inhibition of in vitro angiogenesis by 2-methoxy- and 2-ethyl-estrogen sulfamates.

Sulfamoylation of 2-methoxyestrone (2-MeOE1) was shown previously to enhance its potency as an anti-proliferative agent against breast cancer cells. We have examined the ability of a series of 2-methoxyestradiol (2-MeOE2) and 2-ethylestradiol (2-EtE2) sulfamates to inhibit angiogenesis in vitro. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate were potent inhibitors of human umbilical vein endothelial cell (HUVEC) proliferation with IC(50) values of 0.05 microM and 0.01 microM, respectively. A novel co-culture system, in which endothelial cells were cultured in a matrix of human dermal fibroblasts, was also used to assess the anti-angiogenic potential of these drugs. In this system endothelial cells proliferate and migrate through the culture matrix to form tubule structures. Whereas 2-MeOE2 (1.0 microM) caused a small reduction in tubule formation, both 2-MeOE2 bis-sulfamate (0.1 microM) and 2-EtE2 sulfamate (0.1 microM) almost completely abolished tubule formation. 2-MeOE2 bis-sulfamate and 2-EtE2 sulfamate both induced BCL-2 phosphorylation, p53 protein expression and apoptosis in HUVECs. Microarray analysis of a limited number of genes known to be involved in the angiogenic process did not show any gross changes in cells treated with the 2-substituted estrogens. The sulfamoylated derivatives of 2-MeOE2 and 2-EtE2 are potent inhibitors of in vitro angiogenesis and both compounds should have therapeutic potential.