555 research outputs found
A fast and robust patient specific Finite Element mesh registration technique: application to 60 clinical cases
Finite Element mesh generation remains an important issue for patient
specific biomechanical modeling. While some techniques make automatic mesh
generation possible, in most cases, manual mesh generation is preferred for
better control over the sub-domain representation, element type, layout and
refinement that it provides. Yet, this option is time consuming and not suited
for intraoperative situations where model generation and computation time is
critical. To overcome this problem we propose a fast and automatic mesh
generation technique based on the elastic registration of a generic mesh to the
specific target organ in conjunction with element regularity and quality
correction. This Mesh-Match-and-Repair (MMRep) approach combines control over
the mesh structure along with fast and robust meshing capabilities, even in
situations where only partial organ geometry is available. The technique was
successfully tested on a database of 5 pre-operatively acquired complete femora
CT scans, 5 femoral heads partially digitized at intraoperative stage, and 50
CT volumes of patients' heads. The MMRep algorithm succeeded in all 60 cases,
yielding for each patient a hex-dominant, Atlas based, Finite Element mesh with
submillimetric surface representation accuracy, directly exploitable within a
commercial FE software
Framework for a low-cost intra-operative image-guided neuronavigator including brain shift compensation
In this paper we present a methodology to address the problem of brain tissue
deformation referred to as 'brain-shift'. 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
pre-operative patient imaging to locate the surgical target, such as a tumour
or a functional area. After a general description of the framework of our
intra-operative image-guided system, we describe a procedure to generate
patient specific finite element meshes of the brain and propose a biomechanical
model which can take into account tissue deformations and surgical procedures
that modify the brain structure, like tumour or tissue resection
A 3D biomechanical vocal tract model to study speech production control: How to take into account the gravity?
This paper presents a modeling study of the way speech motor control can deal
with gravity to achieve steady-state tongue positions. It is based on
simulations carried out with the 3D biomechanical tongue model developed at
ICP, which is now controlled with the Lambda model (Equilibrium-Point
Hypothesis). The influence of short-delay orosensory feedback on posture
stability is assessed by testing different muscle force/muscle length
relationships (Invariant Characteristics). Muscle activation patterns necessary
to maintain the tongue in a schwa position are proposed, and the relations of
head position, tongue shape and muscle activations are analyzed
Modeling the production of VCV sequences via the inversion of a biomechanical model of the tongue
A control model of the production of VCV sequences is presented, which
consists in three main parts: a static forward model of the relations between
motor commands and acoustic properties; the specification of targets in the
perceptual space; a planning procedure based on optimization principles.
Examples of simulations generated with this model illustrate how it can be used
to assess theories and models of coarticulation in speech
A Muscle Model Based on Feldman's Lambda Model: 3D Finite Element Implementation
This paper presents the introduction of Feldman's muscle model in a three
dimensional continuum finite element model of the human face. This model is
compared to the classical Hill-type muscle modelComment: CMBBE'2013, Salt Lake City : United States (2013
3D statistical facial reconstruction
The aim of craniofacial reconstruction is to produce a likeness of a face
from the skull. Few works in computerized assisted facial reconstruction have
been done in the past, due to poor machine performances and data availability,
and major works are manually reconstructions. In this paper, we present an
approach to build 3D statistical models of the skull and the face with soft
tissues from the skull of one individual. Results on real data are presented
and seem promising
Orbital and Maxillofacial Computer Aided Surgery: Patient-Specific Finite Element Models To Predict Surgical Outcomes
This paper addresses an important issue raised for the clinical relevance of
Computer-Assisted Surgical applications, namely the methodology used to
automatically build patient-specific Finite Element (FE) models of anatomical
structures. From this perspective, a method is proposed, based on a technique
called the Mesh-Matching method, followed by a process that corrects mesh
irregularities. The Mesh-Matching algorithm generates patient-specific volume
meshes from an existing generic model. The mesh regularization process is based
on the Jacobian matrix transform related to the FE reference element and the
current element. This method for generating patient-specific FE models is first
applied to Computer-Assisted maxillofacial surgery, and more precisely to the
FE elastic modelling of patient facial soft tissues. For each patient, the
planned bone osteotomies (mandible, maxilla, chin) are used as boundary
conditions to deform the FE face model, in order to predict the aesthetic
outcome of the surgery. Seven FE patient-specific models were successfully
generated by our method. For one patient, the prediction of the FE model is
qualitatively compared with the patient's post-operative appearance, measured
from a Computer Tomography scan. Then, our methodology is applied to
Computer-Assisted orbital surgery. It is, therefore, evaluated for the
generation of eleven patient-specific FE poroelastic models of the orbital soft
tissues. These models are used to predict the consequences of the surgical
decompression of the orbit. More precisely, an average law is extrapolated from
the simulations carried out for each patient model. This law links the size of
the osteotomy (i.e. the surgical gesture) and the backward displacement of the
eyeball (the consequence of the surgical gesture)
Modeling the consequences of tongue surgery on tongue mobility
This paper presents the current achievements of a long term project aiming at
predicting and assessing the impact of tongue and mouth floor surgery on tongue
mobility. The ultimate objective of this project is the design of a software
with which surgeons should be able (1) to design a 3D biomechanical model of
the tongue and of the mouth floor that matches the anatomical characteristics
of each patient specific oral cavity, (2) to simulate the anatomical changes
induced by the surgery and the possible reconstruction, and (3) to
quantitatively predict and assess the consequences of these anatomical changes
on tongue mobility and speech production after surgery
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