In-vivo measurement of the human soft tissues constitutive laws. Applications to Computer Aided Surgery

In the 80's, biomechanicians were asked to work on Computer Aided Surgery applications since orthopaedic surgeons were looking for numerical tools able to predict risks of fractures. More recently, biomechanicians started to address soft tissues arguing that most of the human body is made of such tissues that can move as well as deform during surgical gestures [1]. An intra-operative use of a continuous Finite Element (FE) Model of a given tissue mainly faces two problems: (1) the numerical simulations have to be "interactive", i.e. sufficiently fast to provide results during surgery (which can be a strong issue in the context of hyperelastic models for example) and (2) during the intervention, the surgeon needs a device that can be used to provide to the model an estimation of the patient-specific constitutive behaviour of the soft tissues. This work proposes an answer to the second point, with the design of a new aspiration device aiming at characterizing the in vivo constitutive laws of human soft tissues. The device was defined in order to permit sterilization as well an easy intra-operative use

Automatic finite elements mesh generation from planar contours of the brain: an image driven 'blobby' approach

In this paper, we address the problem of automatic mesh generation for finite elements modeling of anatomical organs for which a volumetric data set is available. In the first step a set of characteristic outlines of the organ is defined manually or automatically within the volume. The outlines define the "key frames" that will guide the procedure of surface reconstruction. Then, based on this information, and along with organ surface curvature information extracted from the volume data, a 3D scalar field is generated. This field allows a 3D reconstruction of the organ: as an iso-surface model, using a marching cubes algorithm; or as a 3D mesh, using a grid "immersion" technique, the field value being used as the outside/inside test. The final reconstruction respects the various topological changes that occur within the organ, such as holes and branching elements

Framework and Bio-Mechanical Model for a Per-Operative Image-Guided Neuronavigator Including 'Brain-Shift' Compensation

In this paper we present a methodology to adress the problem of brain tissue deformation referred to as "brainshift". This deformation occurs throughout a neurosurgery intervention and strongly alters the accuracy of the neuronavigation systems used to date in clinical routine which rely solely on preoperative patient imaging to locate the surgical target, such as a tumour or a functional area. After a general description of the framework of our intraoperative image-guided system, we propose a biomechanical model of the brain which can take into account interactively such deformations as well as surgical procedures that modify the brain structure, like tumour or tissue resection

Computer-aided planning for zygomatic bone reconstruction in maxillofacial traumatology

An optimal planning procedure has been proposed to define the target position of the zygomatic bone following a fracture of the mid-face skeleton. The protocol has been successfully tested on healthy subjects, and ensures the global symmetry of the face could be obtained after the reconstruction surgery. Now that the planning procedure is available, the next step of this project will be to develop an intra-operative guiding system to help the surgeon to follow the planning. This procedure will mainly rely on the intra-operative registration of the zygomatic bone fragment, and the design of specific surgical ancillaries for cranio-maxillofacial surgery

Viabilidad de producción de energía eléctrica en la vivienda a partir de sistemas de paneles solares en fraccionamientos estudiados de Culiacán - Área Metropolitana de Guadalajara

El presente proyecto pretende evaluar la viabilidad económica del uso de paneles solares en la vivienda mexicana no perteneciente a estratos socioeconómicos altos, y comprender la relación entre los habitantes y el consumo de electricidad, así como su punto de vista respecto a la autoproducción con otras fuentes de energías renovables, en particular los paneles solares. Para ello, se realizó un estudio comparativo en tres áreas de distinto nivel socioeconómico en el Área Metropolitana de Guadalajara y en Culiacán, Sinaloa, a través del uso de métodos cualitativos y cuantitativos: análisis de datos secundarios, observación directa, entrevistas semiestructuradas, encuestas a nivel de los hogares y generación de escenarios económicos. Los resultados señalan que aun cuando en el corto plazo hay condiciones poco favorables para una transición hacia las energías renovables en estratos sociales con menores recursos—particularmente por los subsidios económicos—, a mediano y largo plazo parece haber mejores condiciones para su uso debido a la caída progresiva en los costos de los paneles solares, los avances tecnológicos y las modificaciones en las políticas energéticas a nivel nacional. En espera de aportar un mayor bienestar a las familias mexicanas y lograr un consumo eficiente de energía, se proponen algunos lineamientos normativos y estrategias de difusión que podrían ampliar el uso de esta tecnología y transitar hacia una sociedad energéticamente más sustentable, y orientar al país en el marco del cumplimiento de los compromisos adquiridos en los tratados internacionales.ITESO, A.C.Consejo Nacional de Ciencia y Tecnologí

Biomechanics applied to computer-aided diagnosis: examples of orbital and maxillofacial surgeries

This paper introduces the methodology proposed by our group to model the biological soft tissues deformations and to couple these models with Computer-Assisted Surgical (CAS) applications. After designing CAS protocols that mainly focused on bony structures, the Computer Aided Medical Imaging group of Laboratory TIMC (CNRS, France) now tries to take into account the behaviour of soft tissues in the CAS context. For this, a methodology, originally published under the name of the Mesh-Matching method, has been proposed to elaborate patient specific models. Starting from an elaborate manually-built "generic" Finite Element (FE) model of a given anatomical structure, models adapted to the geometries of each new patient ("patient specific" FE models) are automatically generated through a non-linear elastic registration algorithm. This paper presents the general methodology of the Mesh-Matching method and illustrates this process with two clinical applications, namely the orbital and the maxillofacial computer-assisted surgeries