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Biomedical subjects

Fernando Bello

Publications and source records attributed to Fernando Bello.

15 recordsLinked to original sources
PubMed2006

The use of a GripForce system to map force distribution patterns of laparoscopic instruments.

While it is acknowledged that the forces required to manipulate laparoscopic instruments can be significant and are important in terms of potential discomfort after prolonged use, no systematic study has been conducted. In this paper we present a GripForce system that allows for the mapping of force distribution patterns of laparoscopic instruments. Initial results showed significant differences in force distribution between various instrument handles, thus demonstrating the viability of the system and proposed methodology. Analysis of force distribution patterns of laparoscopic instruments can help towards improving instrument design, better understanding the relationship between force applied and performance, as well as provide useful feedback to trainees and surgeons.

Computer Simulation↗
PubMed2005

Synchronized video and motion analysis for the assessment of procedures in the operating theater.

HYPOTHESIS: Objective assessment of surgical skill has recently been shown to be possible through the use of dexterity-based and video analysis systems. The aim of this study was to synchronize these 2 modalities to produce a comprehensive surgical assessment tool. DESIGN: The Imperial College Surgical Assessment Device is a dexterity-based motion analysis device that has been developed in the Department of Surgical Oncology and Technology by the Surgical Computing and Imaging Research Group. Further advances to this system have been made to enable synchronized acquisition of hand kinematics and video from real procedures, and their concurrent analysis. To test the feasibility of the system, 10 laparoscopic cholecystectomies performed by 5 different surgeons on consenting patients were recorded. Analysis focused on the entire procedure and also on specific parts of the operation such as the clipping and cutting of the cystic duct and artery. RESULTS: Dexterity analysis was performed using the objective measures of time, path length, number of movements, velocities, and trajectories. Comparative analysis of a surgeon's dexterity was carried out on the whole procedure and by using the synchronized zoom facility in the software. Kinematic signals revealed rapid changes in velocity caused by alternating between different instruments or occurring after complications such as bleeding. CONCLUSION: This new motion analysis system has been shown to be an effective tool for the comprehensive assessment of operative procedures.

Cholecystectomy, Laparoscopic↗
PubMed2005

Laparoscopic task recognition using Hidden Markov Models.

Surgical skills assessment has been paid increased attention over the last few years. Stochastic models such as Hidden Markov Models have recently been adapted to surgery to discriminate levels of expertise. Based on our previous work combining synchronized video and motion analysis we present preliminary results of a HMM laparoscopic task recognizer which aims to model hand manipulations and to identify and recognize simple surgical tasks.

Clinical Competence↗
PubMed2005

Soft tissue deformation using a nonlinear hierarchical finite element model with real-time online refinement.

Simulating soft tissue deformation in real-time is a requirement for realistically rendering the VR interaction between human organs and surgical tools. Finite Element Model (FEM) describes complex mechanical and physiological behaviour but it is computationally too demanding especially when a nonlinear model is to be implemented. For this reason, we introduce a multiresolution approach to FEM that only employs the region of the object under deformation to find the solution of the differential equations of motion. In order to increase the quality of the deformation, refinement of the original mesh is performed with the insertion of new surface nodes in real-time in the region of interaction. To guarantee the stability of the nonlinear model, the presence of flat tetrahedra (slivers) has to be avoided; therefore a sliver elimination technique has been implemented resulting in a more stable simulation.

Clinical Competence↗
PubMed2005

Facial plastic surgery planning using a 3D surface deformation tool.

The range of facial malformations that plastic surgeons are asked to alter is wide. Even a subtle deformity may strongly affect both the way a person perceives herself as well as her quality of life. Moreover, the changes achieved during craniofacial surgery often result in dramatic differences on the face of the patient. Consequently, both surgeons and patients would benefit from the visual approximation of the outcome of the operation provided by adequate three dimensional planning tools. In this paper we propose a three-dimensional texture-mapped surface deformation tool as part of a planning system for rhinoplasty.

Elasticity↗
PubMed2004

An active constraint environment for minimally invasive heart surgery: early experience of a cutting operation.

Master/slave telemanipulator systems can be applied in minimally invasive heart surgery. However, due to the beating heart and difficulties of finding inner points inside the heart, a surgical task operation such as cutting can be very difficult. In order to avoid surgical error, the "active constraint" concept can be applied. This paper shows an example of an "active constraint" environment used for minimally invasive heart surgery. Experiments have been carried out for a 2-DOF master and the preliminary results validate the present approach.

Minimally Invasive Surgical Procedures↗
PubMed2004

Real-time synchronization of kinematic and video data for the comprehensive assessment of surgical skills.

Surgical dexterity in operating theatres has traditionally been assessed subjectively. Electromagnetic (EM) motion tracking systems such as the Imperial College Surgical Assessment Device (ICSAD) have been shown to produce valid and accurate objective measures of surgical skill. To allow for video integration we have modified the data acquisition and built it within the ROVIMAS analysis software. We then used ActiveX 9.0 DirectShow video capturing and the system clock as a time stamp for the synchronized concurrent acquisition of kinematic data and video frames. Interactive video/motion data browsing was implemented to allow the user to concentrate on frames exhibiting certain kinematic properties that could result in operative errors. We exploited video-data synchronization to calculate the camera visual hull by identifying all 3D vertices using the ICSAD electromagnetic sensors. We also concentrated on high velocity peaks as a means of identifying potential erroneous movements to be confirmed by studying the corresponding video frames. The outcome of the study clearly shows that the kinematic data are precisely synchronized with the video frames and that the velocity peaks correspond to large and sudden excursions of the instrument tip. We validated the camera visual hull by both video and geometrical kinematic analysis and we observed that graphs containing fewer sudden velocity peaks are less likely to have erroneous movements. This work presented further developments to the well-established ICSAD dexterity analysis system. Synchronized real-time motion and video acquisition provides a comprehensive assessment solution by combining quantitative motion analysis tools and qualitative targeted video scoring.

Biomechanical Phenomena↗
PubMed2004

Soft tissue deformation using a Hierarchical Finite Element Model.

Simulating soft tissue deformation in real-time has become increasingly important in order to provide a realistic virtual environment for training surgical skills. Several methods have been proposed with the aim of rendering in real-time the mechanical and physiological behaviour of human organs, one of the most popular being Finite Element Method (FEM). In this paper we present a new approach to the solution of the FEM problem introducing the concept of parent and child mesh within the development of a hierarchical FEM. The online selection of the child mesh is presented with the purpose to adapt the mesh hierarchy in real-time. This permits further refinement of the child mesh increasing the detail of the deformation without slowing down the simulation and giving the possibility of integrating force feedback. The results presented demonstrate the application of our proposed framework using a desktop virtual reality (VR) system that incorporates stereo vision with integrated haptics co-location via a desktop Phantom force feedback device.

Connective Tissue↗
PubMed2004

Validation of soft tissue properties in surgical simulation with haptic feedback.

Numerous experiments are being conducted to extract soft tissue values for their integration into VR surgical simulations with haptic feedback. Haptic feedback has been shown to be relevant in laparoscopic surgery, however to date no experiments have been conducted to test user sensitivity to changes in soft tissue values in surgical simulations, and how users perception of 'reality' differs from experimentally determined soft tissue values. In this study we conduct a series of experiments investigating haptic sensitivity, haptic differentiation and comparing experimental and empirical values.

Connective Tissue↗
PubMed2002

Vascular trauma in Latin America: a regional survey.

As has been demonstrated, significant differences exist in demographics and the likelihood of accidents among Latin American countries; however, when figures were standardized, they showed a clear similarity in all the reviewed features of vascular trauma. A total of 66.4% of cases were managed solely on a clinical basis, with 78.9% of surgical procedures being performed within 6 hours of injury. Vascular repair was attempted in 84% of arterial injuries and 43% of venous injuries. Results are extremely good, with an 89% rate of success, especially considering that 63% of injuries were gunshot wounds and that the largest series, from Brazil, had a 21.3% rate of abdominopelvic injuries. The mortality rate amounted to 12.7%, but associated injuries, and particularly multiple trauma, account for 50.0% of the deaths.

Arteries↗
PubMedDate not supplied

FDG-PET findings in the Wernicke-Korsakoff syndrome.

This study reports FDG-PET findings in Wernicke-Korsakoff patients. Twelve patients suffering amnesia arising from the Korsakoff syndrome were compared with 10 control subjects without alcohol-related disability. Subjects received [18F]-fluorodeoxyglucose (FDG-PET) imaging as well as neuropsychological assessment and high-resolution MR imaging with volumetric analysis. Volumetric MRI analysis had revealed thalamic and mamillary body atrophy in the patient group as well as frontal lobe atrophy with relative sparing of medial temporal lobe structures. Differences in regional metabolism were identified using complementary region of interest (ROI) and statistical parametric mapping (SPM) approaches employing either absolute methods or a reference region approach to increase statistical power. In general, we found relative hypermetabolism in white matter and hypometabolism in subcortical grey matter in Korsakoff patients. When FDG uptake ratios were examined with occipital lobe metabolism as covariate reference region, Korsakoff patients showed widespread bilateral white matter hypermetabolism on both SPM and ROI analysis. When white matter metabolism was the reference covariate; Korsakoff patients showed relative hypometabolism in the diencephalic grey matter, consistent with their known underlying neuropathology, and medial temporal and retrosplenial hypometabolism, interpreted as secondary metabolic effects within the diencephalic-limbic memory circuits. There was also evidence of a variable degree of more general frontotemporal neocortical hypometabolism on some, but not all, analyses.

Adult↗
PubMedDate not supplied

Conceptual framework for laparoscopic VR simulators.

Availability of YR laparoscopic simulation for surgical training has increased significantly. Nevertheless, few studies have explored such simulators' requirements and the degree of fidelity necessary to provide effective educational tools. The authors aim to identify which didactic resources available in YR simulation technologies are most important for laparoscopic training.

Computer Graphics↗
PubMedDate not supplied

Online remeshing for soft tissue simulation in surgical training.

To graphically model and animate the realistic behavior of deformable tissue in surgical simulations, the authors' system adapts tetrahedra resolution by dynamically retessellating the mesh in and around the regions of interest. This technique overcomes limitations of previous methods that made it difficult to modify the mesh's topology online.

Computer Graphics↗