The use of the eye-fixation-related potential to investigate visual perception in professional domains with high attentional demand: a literature review

INTRODUCTION

Visual attention is a cognitive skill related to visual perception and neural activity, and also moderated by expertise, in time-constrained professional domains (e.g., aviation, driving, sport, surgery). However, the contribution of both perceptual and neural processes on performance has been studied separately in the literature.

DEVELOPMENT

We defend an integration of visual and neural signals to offer a more complete picture of the visual attention displayed by professionals of different skill levels when performing free-viewing tasks. Specifically, we propose to zoom the analysis in data related to the quiet eye and P300 component jointly, as a novel signal processing approach to evaluate professionals' visual attention.

CONCLUSION

This review highlights the advantages of using portable eye trackers and electroencephalogram systems altogether, as a promising technique for a better understanding of early cognitive components related to attentional processes. Altogether, the eye-fixation-related potentials method may provide a better understanding of the cognitive mechanisms employed by the participants in natural settings, revealing what visual information is of interest for participants and distinguishing the neural bases of visual attention between targets and non-targets whenever they perceive a stimulus during free viewing experiments.

A Serious Game for Cognitive Stimulation of Older People With Mild Cognitive Impairment: Design and Pilot Usability Study

Background

Cognitive stimulation of older people helps prevent, and even treat, age-related diseases, such as mild cognitive impairment. Playing games reduces the probability of experiencing this pathology, which is related to the loss of the ability to carry out some instrumental activities of daily living.

Objective

This work describes the design and development of a serious game for the cognitive stimulation of older people, with exercises related to the daily life task of shopping. A pilot study for its preliminary usability validation is also presented.

Methods

The designed serious game includes 4 exercises consisting of shopping in a hypermarket, ordering products, making payments, and organizing the purchase, thus dealing with the most frequent cognitive problems of older people associated with episodic declarative memory, naming, calculation, and organization, respectively.

Results

A total of 19 older people participated in the pilot study for the usability validation of the serious game. They indicated that they like the aesthetic and interesting topic of the game. They reported that it provides a high level of entertainment and could be useful in daily life for mental stimulation. The participants found the serious game to be intuitive, but the ease of use and readability of the instructions could be improved.

Conclusions

This study suggests that the innovative serious game developed could be accepted by older people for their cognitive stimulation to prevent or treat mild cognitive impairment, although a long-term intervention study should be performed as future work. Its ecological validity design, with everyday tasks, adaptable levels of difficulty, and motivational mechanisms, is a differentiating factor compared to similar serious games.

Home-based exercise interventions delivered by technology in older adults: A scoping review of technological tools usage

BACKGROUND

Despite technology-based systems being considered promising tools to stimulate and increase physical function at home, most older adults are unfamiliar with technology, which may pose some difficulties. Technology-related parameters, such as adherence, acceptance, and acceptability, are crucial to achieving higher efficacy levels of home-based exercise interventions delivered by technology. In this scoping review, we aimed to revise the use of home-based technological tools to improve physical function in the older population, focusing on the user's experience and perspective. Methods This scoping review was conducted following PRISMA guidelines. The search was conducted in April 2022 and updated in April 2023. A total of 45 studies were included in the review. Results Most studies (95.5%) met the technology usage levels defined by the research team or reported satisfactory technology usage levels. Positive health-related outcomes were reported in 80% of studies. Although the existence of guidelines to correctly define and use measures associated with technology use, including adherence, acceptance and acceptability, some terms are still being used interchangeably. Some concerns related to the lack of an international consensus regarding technology usage measures and the exclusion of older adults who did not own or have previous experience with technology in a large percentage of the included studies may have limited the results obtained. Conclusions Altogether, home-based exercise interventions delivered through technology were associated with positive health-related outcomes in older adults, and technology usage levels are considered satisfactory. Older adults are willing and able to use technology autonomously if adequate support is provided.

Biopolymers for Tissue Engineering: Crosslinking, Printing Techniques, and Applications

Currently, tissue engineering has been dedicated to the development of 3D structures through bioprinting techniques that aim to obtain personalized, dynamic, and complex hydrogel 3D structures. Among the different materials used for the fabrication of such structures, proteins and polysaccharides are the main biological compounds (biopolymers) selected for the bioink formulation. These biomaterials obtained from natural sources are commonly compatible with tissues and cells (biocompatibility), friendly with biological digestion processes (biodegradability), and provide specific macromolecular structural and mechanical properties (biomimicry). However, the rheological behaviors of these natural-based bioinks constitute the main challenge of the cell-laden printing process (bioprinting). For this reason, bioprinting usually requires chemical modifications and/or inter-macromolecular crosslinking. In this sense, a comprehensive analysis describing these biopolymers (natural proteins and polysaccharides)-based bioinks, their modifications, and their stimuli-responsive nature is performed. This manuscript is organized into three sections: (1) tissue engineering application, (2) crosslinking, and (3) bioprinting techniques, analyzing the current challenges and strengths of biopolymers in bioprinting. In conclusion, all hydrogels try to resemble extracellular matrix properties for bioprinted structures while maintaining good printability and stability during the printing process.

Clinical Validation Benchmark Dataset and Expert Performance Baseline for Colorectal Polyp Localization Methods

Colorectal cancer is one of the leading death causes worldwide, but, fortunately, early detection highly increases survival rates, with the adenoma detection rate being one surrogate marker for colonoscopy quality. Artificial intelligence and deep learning methods have been applied with great success to improve polyp detection and localization and, therefore, the adenoma detection rate. In this regard, a comparison with clinical experts is required to prove the added value of the systems. Nevertheless, there is no standardized comparison in a laboratory setting before their clinical validation. The ClinExpPICCOLO comprises 65 unedited endoscopic images that represent the clinical setting. They include white light imaging and narrow band imaging, with one third of the images containing a lesion but, differently to another public datasets, the lesion does not appear well-centered in the image. Together with the dataset, an expert clinical performance baseline has been established with the performance of 146 gastroenterologists, who were required to locate the lesions in the selected images. Results shows statistically significant differences between experience groups. Expert gastroenterologists' accuracy was 77.74, while sensitivity and specificity were 86.47 and 74.33, respectively. These values can be established as minimum values for a DL method before performing a clinical trial in the hospital setting.

Computational simulation-based comparative analysis of standard 3D printing and conical nozzles for pneumatic and piston-driven bioprinting

Bioprinting is an application of additive manufacturing that can deliver promising results in regenerative medicine. Hydrogels, as the most used materials in bioprinting, are experimentally analyzed to assure printability and suitability for cell culture. Besides hydrogel features, the inner geometry of the microextrusion head might have an equal impact not only on printability but also on cellular viability. In this regard, standard 3D printing nozzles have been widely studied to reduce inner pressure and get faster printings using highly viscous melted polymers. Computational fluid dynamics is a useful tool capable of simulating and predicting the hydrogel behavior when the extruder inner geometry is modified. Hence, the objective of this work is to comparatively study the performance of a standard 3D printing and conical nozzles in a microextrusion bioprinting process through computational simulation. Three bioprinting parameters, namely pressure, velocity, and shear stress, were calculated using the level-set method, considering a 22G conical tip and a 0.4 mm nozzle. Additionally, two microextrusion models, pneumatic and piston-driven, were simulated using dispensing pressure (15 kPa) and volumetric flow (10 mm³/s) as input, respectively. The results showed that the standard nozzle is suitable for bioprinting procedures. Specifically, the inner geometry of the nozzle increases the flow rate, while reducing the dispensing pressure and maintaining similar shear stress compared to the conical tip commonly used in bioprinting.

CONTENT VALIDATION OF THREE MODULES FOR ONLINE TRAINING OF MINIMALLY INVASIVE SURGERY

Introduction

Training tools should follow a thorough validation process that assure their value before their wider use. In this regard, three online modules for laparoscopic cholecystectomy, lumbar punction and knee arthroscopy have been created for an integrative Learning Management System (LMS) that connects external assets, therefore allowing training of technical and nontechnical skills. This work focuses on the content validation of the modules to determine the appropriateness of the material for learning purposes.

Methods

The contents for the three modules have been developed following a 3D pedagogical model designed for e-learning in minimally invasive surgery. Experts were requested to rate 10 items about the contents and the activities included within the modules. Rating was done on a 5-point Likert scale (5-Strongly agree, 1-Strongly disagree).

Results

Six experts took part in the study. Contents were well rated as unique (4.17), sufficient to cover the learning objectives (4.50), up to date (4.33), realistic and relevant (4.83), professional (4.67), with adequate assessment (4), useful forum (4.33), good quality multimedia contents (4) but not so innovative (3.83). Lastly, external assets provided added value to the courses (4.5).

Conclusions

In general, experts were satisfied with the structure and the quality of the education material and found them to be well prepared according to the best practice of each profession. Therefore, the modules will be incorporated in the LMS for training, which will be further validated to prove its utility as a training tool.

SUBJECTIVE USABILITY VALIDATION OF A LEARNING MANAGEMENT SYSTEM FOR ONLINE TRAINING OF MINIMALLY INVASIVE SURGERY: COMPARISON BETWEEN EXPERTS AND STUDENTS

Introduction

Remote learning has been increasingly required after the COVID-19 pandemic. In this regard, an integrative Learning Management System (LMS) that connects external assets for technical and nontechnical skills training in minimally invasive surgery has been implemented. Before its wider use as a training tool, a comparison of usability perception between experts and students has been performed.

Methods

The system usability scale (SUS) was used. Users rated the 10-item questionnaire on a 5-point Likert-scale (5-Strongly agree, 1-Strongly disagree), with odd questions referring to positive aspects and even questions to negative ones. Two profiles were considered: experts in surgical training and students and residents. They were requested to use the LMS and complete any of the implemented courses. Comparison between groups was done with a Mann-Whitney U-test.

Results

Seven experts and 110 students participated in the study. Overall, SUS score by experts reached a mean value of 67.14 points [Q1 = 68.05, Q3= 76.81; interquartile range (IQR) = 9.67], while the mean SUS score given by students was 73.09 [Q1 = 65.00, Q3= 84.38; IQR = 19.38]. When comparing both groups, significant differences were not found (p-value=0.639).

Conclusions

Since SUS scores are usually considered to be valid when the average is greater than 68, experts were slightly below, while students surpassed this threshold. Nevertheless, since there were no significant differences, it might be assumed that usability of the LMS is acceptable and it will not hinder the training process, although further studies to prove its pedagogical value are required.

DEVELOPMENT OF A NATURAL POLYMER-BASED HYDROGEL FOR BIOENGINEERED VASCULAR GRAFTS

Introduction

Cardiovascular diseases are a main cause of death globally, and their treatment implies various vascular repairs through different techniques like angioplasty, stent placement in the blocked artery, or bypass surgery. Artificial grafts would significantly reduce the number of non-treated patients, but middle and long-term failures compromise their clinical use.

Methods

Herein, we developed a hydrogel composed of gellan gum, gelatin, and sodium alginate for bioengineered vascular graft production. The vascular grafts were characterized by their swelling, porosity, biodegradability, and cytotoxic profile.

Results

The bioengineered materials were easily assembled due to the thermoresponsive nature of the hydrogel and had a vessel-like structure resembling the native vasculature. These vessels had a very controlled swelling degree, and notably, the hydrogel structure was stable and maintained its morphology. The vascular grafts had a porosity of 82.6 ± 4.3% and exhibited a controlled biodegradation rate with a maximum of 24.2 ± 3.0%. As expected, the natural materials used showed no cytotoxicity toward HUVECs cells since they are natural polymers described as biocompatible.

Conclusions

This developed natural hydrogel showed promising potential to be used to develop bioengineered vascular grafts.

PRELIMINARY RESULTS ON FUNCTIONALIZATION OF POLYPROPYLENE SURGICAL MESHES

Introduction

Due to inflammatory response in patients, many efforts have been devoted to developing advanced (biological or bioactive) surgical meshes. Some of them look for new synthetic materials and others work to improve their biocompatibility through different methods (coating, soaking, plasma). However, it is critical to avoid pore obstruction or lose mechanical properties while its amphiphilic behaviour is increased.

Methods

A deposition method was used to functionalize surgical meshes with a polypropylene derivative block copolymer that improved its amphiphilic behaviour. Therefore, this copolymer was dispersed on several solvents with different polarities and chemical natures. Then, meshes were immersed and a chemical adsorption-based coating was performed. Additionally, a qualitative study was carried out by optical and fluorescence microscopy on two size samples: small (1 cm2 squares) and large (standard T bone shapes).

Results

First, pore obstruction was perfectly avoided in small samples but was partially present in large samples. Second, the deposition was thicker with polar solvent in both sizes. And finally, fluorescence analysis showed a homogeneous and smooth coating with the most polar solvent.

Conclusions

After exposure to UV light, small samples show a better coating while large one's present irregular adherences on their surface. Moreover, the aprotic polar solvent provides a thickness layer and a smooth mesh surface.

TOWARDS AN UNIFIED FRAMEWORK FOR VALIDATING DEEP LEARNING METHODS FOR COLORECTAL POLYPS: FIRST STEPS

INTRODUCTION

Deep learning techniques have significantly contributed to the field of medical imaging analysis. In case of colorectal cancer, they have shown a great utility for increasing the adenoma detection rate at colonoscopy, but a common validation methodology is still missing. In this study, we present preliminary efforts towards the definition of a validation framework.

MATERIAL AND METHODS

Different models based on different backbones and encoder-decoder architectures have been trained with a publicly available dataset that contains white light and NBI colonoscopy videos, with 76 different lesions from colonoscopy procedures in 48 human patients. A computer aided detection (CADe) demonstrator has been implemented to show the performance of the models.

RESULTS

This CADe demonstrator shows the areas detected as polyp by overlapping the predicted mask on the endoscopic image. It allows selecting the video to be used, among those from the test set. Although it only present basic features such as play, pause and moving to the next video, it easily loads the model and allows for visualization of results. The demonstrator is accompanied by a set of metrics to be used depending on the aimed task: polyp detection, localization and segmentation.

CONCLUSIONS

The use of this CADe demonstrator, together with a publicly available dataset and predefined metrics will allow for an easier and more fair comparison of methods. Further work is still required to validate the proposed framework.

Unravelling the effect of data augmentation transformations in polyp segmentation

PURPOSE

Data augmentation is a common technique to overcome the lack of large annotated databases, a usual situation when applying deep learning to medical imaging problems. Nevertheless, there is no consensus on which transformations to apply for a particular field. This work aims at identifying the effect of different transformations on polyp segmentation using deep learning.

METHODS

A set of transformations and ranges have been selected, considering image-based (width and height shift, rotation, shear, zooming, horizontal and vertical flip and elastic deformation), pixel-based (changes in brightness and contrast) and application-based (specular lights and blurry frames) transformations. A model has been trained under the same conditions without data augmentation transformations (baseline) and for each of the transformation and ranges, using CVC-EndoSceneStill and Kvasir-SEG, independently. Statistical analysis is performed to compare the baseline performance against results of each range of each transformation on the same test set for each dataset.

RESULTS

This basic method identifies the most adequate transformations for each dataset. For CVC-EndoSceneStill, changes in brightness and contrast significantly improve the model performance. On the contrary, Kvasir-SEG benefits to a greater extent from the image-based transformations, especially rotation and shear. Augmentation with synthetic specular lights also improves the performance.

CONCLUSION

Despite being infrequently used, pixel-based transformations show a great potential to improve polyp segmentation in CVC-EndoSceneStill. On the other hand, image-based transformations are more suitable for Kvasir-SEG. Problem-based transformations behave similarly in both datasets. Polyp area, brightness and contrast of the dataset have an influence on these differences.

Temperature and Humidity PID Controller for a Bioprinter Atmospheric Enclosure System

Bioprinting is a complex process, highly dependent on bioink properties (materials and cells) and environmental conditions (mainly temperature, humidity and CO₂ concentration) during the bioprinting process. To guarantee proper cellular viability and an accurate geometry, it is mandatory to control all these factors. Despite internal factors, such as printing pressures, temperatures or speeds, being well-controlled in actual bioprinters, there is a lack in the controlling of external parameters, such as room temperature or humidity. In this sense, the objective of this work is to control the temperature and humidity of a new, atmospheric enclosure system for bioprinting. The control has been carried out with a decoupled proportional integral derivative (PID) controller that was designed, simulated and experimentally tested in order to ensure the proper operation of all its components. Finally, the PID controller can stabilize the atmospheric enclosure system temperature in 311 s and the humidity in 65 s, with an average error of 1.89% and 1.30%, respectively. In this sense, the proposed atmospheric enclosure system can reach and maintain the proper temperature and humidity values during post-printing and provide a pre-incubation environment that promotes stability, integrity and cell viability of the 3D bioprinted structures.

Hydrogels for Bioprinting: A Systematic Review of Hydrogels Synthesis, Bioprinting Parameters, and Bioprinted Structures Behavior

Nowadays, bioprinting is rapidly evolving and hydrogels are a key component for its success. In this sense, synthesis of hydrogels, as well as bioprinting process, and cross-linking of bioinks represent different challenges for the scientific community. A set of unified criteria and a common framework are missing, so multidisciplinary research teams might not efficiently share the advances and limitations of bioprinting. Although multiple combinations of materials and proportions have been used for several applications, it is still unclear the relationship between good printability of hydrogels and better medical/clinical behavior of bioprinted structures. For this reason, a PRISMA methodology was conducted in this review. Thus, 1,774 papers were retrieved from PUBMED, WOS, and SCOPUS databases. After selection, 118 papers were analyzed to extract information about materials, hydrogel synthesis, bioprinting process, and tests performed on bioprinted structures. The aim of this systematic review is to analyze materials used and their influence on the bioprinting parameters that ultimately generate tridimensional structures. Furthermore, a comparison of mechanical and cellular behavior of those bioprinted structures is presented. Finally, some conclusions and recommendations are exposed to improve reproducibility and facilitate a fair comparison of results.

Deep learning to find colorectal polyps in colonoscopy: A systematic literature review

Colorectal cancer has a great incidence rate worldwide, but its early detection significantly increases the survival rate. Colonoscopy is the gold standard procedure for diagnosis and removal of colorectal lesions with potential to evolve into cancer and computer-aided detection systems can help gastroenterologists to increase the adenoma detection rate, one of the main indicators for colonoscopy quality and predictor for colorectal cancer prevention. The recent success of deep learning approaches in computer vision has also reached this field and has boosted the number of proposed methods for polyp detection, localization and segmentation. Through a systematic search, 35 works have been retrieved. The current systematic review provides an analysis of these methods, stating advantages and disadvantages for the different categories used; comments seven publicly available datasets of colonoscopy images; analyses the metrics used for reporting and identifies future challenges and recommendations. Convolutional neural networks are the most used architecture together with an important presence of data augmentation strategies, mainly based on image transformations and the use of patches. End-to-end methods are preferred over hybrid methods, with a rising tendency. As for detection and localization tasks, the most used metric for reporting is the recall, while Intersection over Union is highly used in segmentation. One of the major concerns is the difficulty for a fair comparison and reproducibility of methods. Even despite the organization of challenges, there is still a need for a common validation framework based on a large, annotated and publicly available database, which also includes the most convenient metrics to report results. Finally, it is also important to highlight that efforts should be focused in the future on proving the clinical value of the deep learning based methods, by increasing the adenoma detection rate.

Validation of the three web quality dimensions of a minimally invasive surgery e-learning platform

INTRODUCTION

E-learning web environments, including the new TELMA platform, are increasingly being used to provide cognitive training in minimally invasive surgery (MIS) to surgeons. A complete validation of this MIS e-learning platform has been performed to determine whether it complies with the three web quality dimensions: usability, content and functionality.

METHODS

21 Surgeons participated in the validation trials. They performed a set of tasks in the TELMA platform, where an e-MIS validity approach was followed. Subjective (questionnaires and checklists) and objective (web analytics) metrics were analysed to achieve the complete validation of usability, content and functionality.

RESULTS

The TELMA platform allowed access to didactic content with easy and intuitive navigation. Surgeons performed all tasks with a close-to-ideal number of clicks and amount of time. They considered the design of the website to be consistent (95.24%), organised (90.48%) and attractive (85.71%). Moreover, they gave the content a high score (4.06 out of 5) and considered it adequate for teaching purposes. The surgeons scored the professional language and content (4.35), logo (4.24) and recommendations (4.20) the highest. Regarding functionality, the TELMA platform received an acceptance of 95.24% for navigation and 90.48% for interactivity.

CONCLUSIONS

According to the study, it seems that TELMA had an attractive design, innovative content and interactive navigation, which are three key features of an e-learning platform. TELMA successfully met the three criteria necessary for consideration as a website of quality by achieving more than 70% of agreements regarding all usability, content and functionality items validated; this constitutes a preliminary requirement for an effective e-learning platform. However, the content completeness, authoring tool and registration process required improvement. Finally, the e-MIS validity methodology used to measure the three dimensions of web quality in this work can be applied to other clinical areas or training fields.

[Application of fluid mechanics and simulation: urinary tract and ureteral catheters.]

The mechanics of urine during its transport from the renal pelvis to the bladder is of great interest for urologists. The knowledge of the different physical variables and their interrelationship, both in physiologic movements and pathologies, will help a better diagnosis and treatment. The objective of this chapter is to show the physics principles and their most relevant basic relations in urine transport, and to bring them over the clinical world. For that, we explain the movement of urine during peristalsis, ureteral obstruction and in a ureter with a stent. This explanation is based in two tools used in bioengineering: the theoretical analysis through the Theory of concontinuous media and Ffluid mechanics and computational simulation that offers a practical solution for each scenario. Moreover, we review other contributions of bioengineering to the field of Urology, such as physical simulation or additive and subtractive manufacturing techniques. Finally, we list the current limitations for these tools and the technological development lines with more future projection.

CONCLUSIONS

In this chapter we aim to help urologists to understand some important concepts of bioengineering, promoting multidisciplinary cooperation to offer complementary tools that help in diagnosis and treatment of diseases.

Virtual reality thread simulation for laparoscopic suturing training

The level of realism in virtual reality trainers might not be proportional to its didactic value. As an example, three exercises to train suturing skills are proposed in this article. They use a discrete thread model with a simple but good enough behaviour, and constitute a training means for three laparoscopic skills: (1) Accurate grasping, which trains grasping a precise point in the thread. (2) Coordinated Pulling, which trains tightening the thread co-ordinately and in different space orientations; and (3) Knotting, which allow the surgeon to practice this manoeuvre. These three exercises, found interesting among experts in surgical training, are now being validated in MIS workshops at the Minimally Invasive Surgery Centre of Cáceres (Spain).