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Planification préopératoire pour ostéotomies autour du genou : d’un modèle numérique tridimensionnel à l’industrialisation de guides patient-spécifique / Preoperative planning for osteotomies around the knee : from a 3D numerical model to patient-specific guides industrialisationDonnez, Mathias 24 October 2018 (has links)
L’Ostéotomie Tibiale de Valgisation (OTV) par ouverture médiale est un traitement conservatif efficace dans le traitement de la gonarthrose médiale chez le patient jeune et actif présentant un défaut d’alignement du membre inférieur. Ce défaut entraine un déséquilibre dans la répartition des charges transitant dans le genou et est un facteur de risque la gonarthrose. L’objectif est de corriger l’alignement en corrigeant une déformation osseuse du tibia proximal. Une coupe osseuse médiolatérale incomplète partant du bord médial de la métaphyse tibiale et orientée vers l’articulation tibio-fibulaire permet de créer une ouverture sur le bord médial par rotation autour de la charnière latérale, épaisseur d’os non-coupée sur le bord latéral. L’importance de l’ouverture dépend de la déformation osseuse et du stade d’arthrose. La réussite de l’OTV par ouverture médiale est conditionnée par une correction précise, un montage d’ostéosynthèse stable et une charnière latérale préservée pendant l’ouverture. L’objectif de cette thèse était de proposer une méthodologie de planification préopératoire à associer à une instrumentation patient-spécifique réalisée en impression 3D. Cette instrumentation devait permettre d’appliquer la correction souhaitée dans les plans frontal et sagittal mais aussi de préserver la charnière latérale pendant la chirurgie. Nos résultats ont montré, grâce aux études in-vitro et in-vivo réalisées au cours de la thèse, que le guide de coupe patient-spécifique développé permet de reproduire avec précision la planification préopératoire en apportant de la sécurité au geste opératoire tant au niveau de la précision que de la préservation de la charnière latérale. / Medial Opening Wedge High Tibial Osteotomy (MOWHTO) is an efficient conservative surgical treatment for young and active patients with moderate medial gonarthrosis and varus lower limb malalignment. Varus malalignment unbalances load distribution in the knee, which is a gonarthrosis risk factor. MOWHTO aims to correct the lower limb alignment by correcting the proximal tibia bony deformity. Incomplete mediolateral cut is performed in the proximal tibia from the medial side of the tibial metaphysis towards the tibiofibular joint, and then opened by rotation around the lateral hinge which is the remaining uncut bone thickness on the lateral side. Amount of the opening depends on the importance of the proximal tibial deformity and on the medial gonarthrosis stage. MOWHTO success remains on precise correction, stable osteosynthesis system and lateral hinge preservation during the opening. Objective of this thesis was to propose a preoperative planning methodology to be associated with 3D printed patientspecific instrumentation. This instrumentation was intended to apply the correction chosen by the surgeon in the frontal and sagittal planes, but also to preserve the lateral hinge during the surgery. Our in-vitro and in-vivo results have shown that the developed patient-specific cutting guide make it possible to accurately reproduce the preoperative planning with security to the surgical gesture by bringing accuracy and lateral hinge preservation.
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Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian gridsGiovannelli, Luca 10 December 2018 (has links)
Se cree que la medicina in silico supondrá uno de los cambios más disruptivos en
el futuro próximo. A lo largo de la última década se ha invertido un gran esfuerzo
en el desarrollo de modelos computacionales predictivos para mejorar el poder de
diagnóstico de los médicos y la efectividad de las terapias. Un punto clave de esta
revolución, será la personalización, que conlleva en la mayoría de los casos, la creación
de modelos computacionales específicos de paciente, también llamados gemelos digitales.
Esta práctica está actualmente extendida en la investigación y existen en el
mercado varias herramientas de software que permiten obtener modelos a partir de
imágenes. A pesar de eso, para poderse usar en la práctica clínica, estos métodos
se necesita reducir drásticamente el tiempo y el trabajo humano necesarios para la
creación de los modelos numéricos.
Esta tésis se centra en la propuesta de la versión basada en imágenes del Cartesian
grid Finite Element Method (cgFEM), una técnica para obtener de forma automática
modelos a partir de imágenes y llevar a cabo análisis estructurales lineales de huesos,
implantes o materiales heterogéneos.
En la técnica propuesta, tras relacionar la escala de los datos de la imágen con
valores de propiedades mecánicas, se usa toda la información contenida en los píxeles
para evaluar las matrices de rigidez de los elementos que homogenizan el comportamiento
elástico de los grupos de píxeles contenidos en cada elemento. Se h-adapta
una malla cartesiana inicialmente uniforme a las características de la imágen usando
un procedimiento eficiente que tiene en cuenta las propiedades elásticas locales asociadas
a los valores de los píxeles. Con eso, se evita un suavizado excesivo de las
propiedades elásticas debido a la integración de los elementos en áreas altamente heterogéneas,
pero, no obstante, se obtienen modelos finales con un número razonable
de grados de libertad.
El resultado de este proceso es una malla no conforme en la que se impone la continudad
C0 de la solución mediante restricciones multi-punto en los hanging nodes.
Contrariamente a los procedimientos estandar para la creación de modelos de Elementos
Finitos a partir de imágenes, que normalmente requieren la definición completa y
watertight de la geometrá y tratan el resultado como un CAD estandar, con cgFEM
no es necesario definir ninguna entidad geométrica dado que el procedimiento propuesto
conduce a una definición implícita de los contornos. Sin embargo, es inmediato
incluirlas en el modelo en el caso de que sea necesario, como por ejemplo superficies
suaves para imponer condiciones de contorno de forma más precisa o volúmenes
CAD de dispositivos para la simulación de implantes. Como consecuencia de eso, la
cantidad de trabajo humano para la creación de modelos se reduce drásticamente.
En esta tesis, se analiza en detalles el comportamiento del nuevo método en problemas
2D y 3D a partir de CT-scan y radiográfias sintéticas y reales, centrandose en
tres clases de problemas. Estos incluyen la simulación de huesos, la caracterización de
materiales a partir de TACs, para lo cual se ha desarrollado la cgFEM virtual characterisation
technique, y el análisis estructural de futuros implantes, aprovechando la
capacidad del cgFEM de combinar fácilmente imágenes y modelos de CAD. / Es creu que la medicina in silico suposarà un dels canvis més disruptius en el futur
pròxim. Al llarg de l'última dècada, s'ha invertit un gran esforç en el desenvolupament
de models computacionals predictius per millorar el poder de diagnòstic dels
metges i l'efectivitat de les teràpies. Un punt clau d'aquesta revolució, serà la personalització,
que comporta en la majoria dels casos la creació de models computacionals
específics de pacient. Aquesta pràctica està actualment estesa en la investigació i hi
ha al mercat diversos software que permeten obtenir models a partir d'imatges. Tot i
això, per a poder-se utilitzar en la pràctica clínica aquests métodes es necessita reduir
dràsticament el temps i el treball humà necessaris per a la seva creació. Aquesta tesi
es centra en la proposta d'una versió basada en imatges del Cartesian grid Finite Element
Method (cgFEM), una técnica per obtenir de forma automàticament models a
partir d'imatges i dur a terme anàlisis estructurals lineals d'ossos, implants o materials
heterogenis. Després de relacionar l'escala del imatge a propietats macàniques corresponents,
s'usa tota la informació continguda en els píxels per a integrar les matrius
de rigidesa dels elements que homogeneïtzen el comportament elàstic dels grups de
píxels continguts en cada element. Es emphh-adapta una malla inicialment uniforme
a les característiques de la imatge usant un procediment eficient que té en compte
les propietats elàstiques locals associades als valors dels píxels. Amb això, s'evita un
suavitzat excessiu de les propietats elàstiques a causa de la integració dels elements en
àrees altament heterogénies, però, tot i això, s'obtenen models finals amb un nombre
raonable de graus de llibertat. El resultat d'aquest procés és una malla no conforme
en la qual s'imposa la continuïtat C0 de la solució mitjançant restriccions multi-punt
en els hanging nodes. Contràriament als procediments estàndard per a la creació de
models d'Elements finits a partir d'imatges, que normalment requereixen la definició
completa i watertight de la geometria i tracten el resultat com un CAD estàndard,
amb cgFEM no cal definir cap entitat geométrica. No obstant això, és immediat
incloure-les en el model en el cas que sigui necessari, com ara superfícies suaus per
imposar condicions de contorn de forma més precisa o volums CAD de dispositius per
a la simulació d'implants. Com a conseqüéncia d'això, la quantitat de treball humà
per a la creació de models es redueix dràsticament. En aquesta tesi, s'analitza en
detalls el comportament del nou métode en problemes 2D i 3D a partir de CT-scan
i radiografies sintétiques i reals, centrant-se en tres classes de problemes. Aquestes
inclouen la simulació d'ossos, la caracterització de materials a partir de TACs, per a
la qual s'ha desenvolupat la cgFEM virtual characterisation technique, i l'anàlisi estructural
de futurs implants, aprofitant la capacitat del cgFEM de combinar fàcilment
imatges i models de CAD. / In silico medicine is believed to be one of the most disruptive changes in the near future.
A great effort has been carried out during the last decade to develop predicting
computational models to increase the diagnostic capabilities of medical doctors and
the effectiveness of therapies. One of the key points of this revolution, will be personalisation,
which means in most of the cases creating patient specific computational
models, also called digital twins. This practice is currently wide-spread in research
and there are quite a few software products in the market to obtain models from
images. Nevertheless, in order to be usable in the clinical practice, these methods
have to drastically reduce the time and human intervention required for the creation
of the numerical models.
This thesis focuses on the proposal of image-based Cartesian grid Finite Element
Method (cgFEM), a technique to automatically obtain numerical models from images
and carry out linear structural analyses of bone, implants or heterogeneous materials.
In the method proposed in this thesis, after relating the image scale to corresponding
elastic properties, all the pixel information will be used for the integration of the
element stiffness matrices, which homogenise the elastic behaviour of the groups of
pixels contained in each element. An initial uniform Cartesian mesh is h-adapted
to the image characteristics by using an efficient refinement procedure which takes
into account the local elastic properties associated to the pixel values. Doing so we
avoid an excessive elastic property smoothing due to element integration in highly
heterogeneous areas, but, nonetheless obtain final models with a reasonable number
of degrees of freedom.
The result of the process is non-conforming mesh in which C0 continuity is enforced
via multipoint constraints at the hanging nodes. In contrast to the standard
procedures for the creation of Finite Element models from images, which usually require
a complete and watertight definition of the geometry and treat the result as a
standard CAD, with cgFEM it is not necessary to define any geometrical entity, as
the procedure proposed leads to an implicit definition of the boundaries. Nonetheless,
they are straightforward to include in the model if necessary, such as smooth surfaces
to impose the boundary conditions more precisely or CAD device volumes for the
simulation of implants. As a consequence, the amount of human work required for
the creation of the numerical models is drastically reduced.
In this thesis, we analyse in detail the new method behaviour in 2D and 3D problems
from CT-scans and X-ray images and synthetic images, focusing on three classes
of problems. These include the simulation of bones, the material characterisation of
solid foams from CT scans, for which we developed the cgFEM virtual characterisation
technique, and the structural analysis of future implants, taking advantage of
the capability of cgFEM to easily mix images and CAD models. / Giovannelli, L. (2018). Direct creation of patient-specific Finite Element models from medical images and preoperative prosthetic implant simulation using h-adaptive Cartesian grids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113644 / TESIS
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Modèles 3D de mélanome métastatique pour l’évaluation in vitro de l’efficacité de molécules de thérapies ciblées / 3D models of metastatic melanoma for in vitro evaluation of targeted therapy efficiencyMorales, Delphine 18 June 2019 (has links)
La sensibilité des cellules de mélanomes aux molécules de thérapies ciblées dépend du microenvironnement tumoral (interactions cellule-cellule et cellule-matrice extracellulaire). Les systèmes tridimensionnels (3D) de culture in vitro reflètent mieux l’architecture structurelle native des tissus et sont attrayants pour l’étude des interactions cellulaires. Nous avons développé et comparé plusieurs modèles de mélanome métastatique : les cellules de mélanomes (SK-MEL-28 et SK-MEL-3, mutées BRAF V600E et SK-MEL-2, BRAF sauvages) cultivées en monocouche (2D) et co-cultivées en 3D sur des équivalents de derme avec des fibroblastes, afin de mieux comprendre les facteurs modulant la sensibilité cellulaire à un inhibiteur de BRAF (BRAFi, Vémurafenib) et au Vémurafenib associé à un inhibiteur de MEK (MEKi, Cobimetinib). La sensibilité cellulaire aux traitements a été évaluée sous différents aspects : prolifération cellulaire (numération cellulaire, incorporation d'EdU, test MTS), analyse des voies de signalisation MAPK et PKB / Akt (Western-blot), apoptose (TUNEL), libération de cytokines et de facteurs de croissance (ELISA) et histologie (modèles 3D). Un effet cytostatique de BRAFi a été observé sur les cellules SK-MEL-28 et SK-MEL-3 cultivées dans les modèles 2D et 3D. La lignée cellulaire SK-MEL-2 était résistante au BRAFi lorsqu'elle a été cultivée en monocouche, mais sensible lorsqu'elle a été co-cultivée avec des fibroblastes incorporés dans une matrice de collagène de type I. Les milieux conditionnés par les fibroblastes 3D (équivalents de derme) ont sensibilisé les cellules SK-MEL-2 (2D) au BRAFi. L'analyse des surnageants de culture cellulaire a révélé que les équivalents de derme libéraient certains facteurs solubles (IL-6, IL-8, HGF, TGF-β) : ces sécrétions ont été modifiées au cours du traitement par Vémurafenib. La combinaison du traitement avec MEKi a renforcé l'action du Vémurafenib sur les cellules de mélanomes métastatiques tout en diminuant la capacité de prolifération des fibroblastes. Des populations de cellules contenant des cellules de mélanomes ou des fibroblastes associés au cancer (CAFs) ont été isolées à partir d'une biopsie de métastase cutanée provenant d'une patiente atteinte d'un mélanome métastatique. Ces cellules ont permis de réaliser des modèles de mélanome métastatique patient-spécifique afin d’étudier in vitro la sensibilité des cellules de la patiente aux traitements dans un microenvironnement tumoral (sécrétion paracrine de cellules stromales et matrice de collagène). Ces modèles prédictifs 3D patient-spécifique pourront être utilisés pour déterminer des stratégies de thérapies personnalisées, ainsi que pour comprendre les phénomènes de résistance des cellules de mélanomes aux traitements. / Melanoma cell sensitivity to targeted therapy molecules is dependent on the tumor microenvironment (cell-cell and cell-extracellular matrix interactions). Three dimensional (3D) in vitro cell culture systems better reflect the native structural architecture of tissues and are attractive to investigate cellular interactions. We have developed and compared several metastatic melanoma models: melanoma cells (SK-MEL-28 and SK-MEL-3, BRAF V600E mutant and SK-MEL-2 BRAF wt) cultured as a monolayer (2D) and co-cultured on 3D dermal equivalents with fibroblasts to better unravel factors modulating cell sensitivity to a BRAF inhibitor (BRAFi, Vemurafenib) and a BRAFi combined with a MEK inhibitor (MEKi, Cobimetinib). Cell sensitivity to treatments was evaluated under various aspects: cell proliferation (cell counting, EdU incorporation, MTS assay), MAPK and PKB/Akt signaling pathway analysis (Western-blotting), apoptosis (TUNEL), cytokine and growth factor release (ELISA) and histology (3D models). A cytostatic effect of BRAFi was observed on SK-MEL-28 and SK-MEL-3 cells in both models. SK-MEL-2 cell line was clearly resistant to BRAFi when cultured as a monolayer but not when co-cultured with 3D fibroblasts embedded in a type I collagen matrix. Conditioned media provided by 3D fibroblasts (dermal equivalents) underlined 2D SK-MEL-2 sensitivity to BRAFi. Cell culture supernatant analysis revealed that dermal equivalents released some soluble factors (IL-6, IL-8, HGF, TGF-β): these secretions were modified during vemurafenib treatment. The combination of treatment with MEKi enhances the action of Vemurafenib on metastatic melanoma cells while decreasing the proliferation capacity of fibroblasts. Cell populations containing melanoma cells or fibroblasts associated with cancer (CAFs) were isolated from a cutaneous metastasis biopsy of a patient with metastatic melanoma. These cells allowed the realization of patient-specific models of metastatic melanoma in order to study in vitro the sensitivity of the patient’s melanoma cells to treatments in a tumor microenvironment (paracrine secretion of stromal cells and collagen matrix). These 3D predictive patient-specific models could be used to determine personalized therapy strategies, as well as to understand the resistance phenomena of melanoma cells to treatments
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Toward Realistic Stiffness-Matched NiTi Skeletal Fixation PlatesJahadakbar, Ahmadreza January 2020 (has links)
No description available.
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The Additively Manufactured Porous NiTi and Ti-6Al-4V in Mandibular Reconstruction: Introducing the Stiffness-Matched and the Variable Stiffness Options for the Reconstruction Plates.Jahadakbar, Ahmadreza January 2016 (has links)
No description available.
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From group to patient-specific analysis of brain function in arterial spin labelling and BOLD functional MRIMaumet, Camille 29 May 2013 (has links) (PDF)
This thesis deals with the analysis of brain function in Magnetic Resonance Imaging (MRI) using two sequences: BOLD functional MRI (fMRI) and Arterial Spin Labelling (ASL). In this context, group statistical analyses are of great importance in order to understand the general mechanisms underlying a pathology, but there is also an increasing interest towards patient-specific analyses that draw conclusions at the patient level. Both group and patient-specific analyses are studied in this thesis. We first introduce a group analysis in BOLD fMRI for the study of specific language impairment, a pathology that was very little investigated in neuroimaging. We outline atypical patterns of functional activity and lateralisation in language regions. Then, we move forward to patient-specific analysis. We propose the use of robust estimators to compute cerebral blood flow maps in ASL. Then, we analyse the validity of the assumptions underlying standard statistical analyses in the context of ASL. Finally, we propose a new locally multivariate statistical method based on an a contrario approach and apply it to the detection of atypical patterns of perfusion in ASL and to activation detection in BOLD functional MRI.
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Molares permanentes de pacientes jovens com cárie profunda versus tratados endodonticamente e restaurados com resina composta bulk fill – Análise da força de mordida e por elementos finitos específico / Pulp caries affected versus endodontic treated and composite resin restored young permanent molars -bite force and specific finite element analysisRodrigues, Monise de Paula 09 February 2018 (has links)
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais / O tratamento endodôntico associado à restauração direta com resina composta
tem sido utilizado para restaurar molares severamente destruídos em pacientes
jovens. O objetivo deste estudo foi avaliar o efeito de diferentes níveis de perda
de estrutura dentária antes e após a realização de tratamento endodôntico e
restauração com resina composta bulk fill na distribuição de tensões e magnitude
da força de mordida. Foram selecionados três pacientes jovens (9, 10 and 12
anos de idade) com primeiros molares com cárie extensa e envolvimento pulpar
com diferentes níveis de perdas de estrutura dentária: PI, manutenção das duas
cristas marginais e de todas as cúspides; PII, manutenção de pelo menos uma
crista marginal e perda mínima de uma cúspide; e PIII, perda de ambas as cristas
marginais, mantendo apenas as cúspides vestibulares. Os molares foram
tratados endodonticamente utilizando técnica de instrumentação rotatória e
obturados com guta-percha e cimento AHPlus (Dentsply) e em seguida foram
restaurados com Filtek Bulk Fill Posterior (3M ESPE). A força de mordida em
Newtons (N) foi mensurada antes e após a intervenção endodôntica e
restauradora na posição habitual de oclusal usando aparelho de força de
mordida por meio de uma célula de carga (Kratos). Tomografias
computadorizadas cone beam foram realizadas antes e após o procedimento
endodôntico/restaurador, e arquivos DICOM (.dcm) foram exportados para o
software Mimics, 3-Matic (Materialize) e Patran (MSC Software) para criação dos
modelos específicos dos pacientes nos dois momentos experimentais. A
aplicação de carga foi simulada por contato oclusal dos dentes antagonistas nas
cargas mensuradas clinicamente em cada momento. Nos modelos que
representam as condições iniciais foram aplicados tanto os valores de força de
mordida (N) mensurados no momento inicial quanto após o procedimento
reabilitador: PI. 30,1/136,6; PII. 34,3/133,4 e PIII. 47,9/124,1 e para os modelos
que representam a condição final foram utilizados os valores obtidos após a
intervenção endodôntica e restauradora: PI. 136,6; PII. 133,4 e PIII. 124,1. As
restaurações foram avaliadas após 2 anos. Após intervenção endodôntica e
restauradora a força de mordida aumentou em 260% (de 36,7±11,6 para
12
131,9±17,8). Antes da intervenção endodôntica e restauradora, as tensões se
concentraram na estrutura coronal e, após a reabilitação foram transferidas de
forma homogênea para a dentina radicular, independente do nível de perda de
estrutura dentária. Quando a carga final foi aplicada nos modelos de condições
iniciais, evidenciou-se elevada concentração de tensão em áreas enfraquecidas
e na região de furca. As restaurações apresentaram desempenho adequado
após 2 anos. A presença de cárie extensa com envolvimento pulpar afetou
negativamente a carga de mordida e aumentou a concentração de tensão na
estrutura frágil o que pode favorecer à ocorrência de fratura dental. O tratamento
endodôntico associado à restauração direta em resina composta bulk fill
demonstrou ser um método eficiente para restabelecer o desempenho
mastigatório e a eficiência biomecânica dos molares jovens com
comprometimento severo da estrutura coronária. / Endodontic treatment (ETT) followed by direct composite resin restoration has
been used for rehabilitating the severely damage molar teeth in young patients.
The aim of this study was to evaluate the effect of the molar teeth with different
levels of the dental structure loss before and after the ETT and direct restoration
with bulk fill resin composite on the stress distribution and the bite force
magnitude. Three young patients (with 9, 10 and 12 years old), with the first
mandibular molar teeth with deep occlusal caries with pulp involvement were
selected attending with different levels of the dental structure loss: PI, both
marginal ridge and all cusps; PII, maintenance of one marginal ridge and loss of
one cusp; and PIII, loss of both marginal ridge, maintaining only buccal cusps.
ETT was restored using Filtek Bulk Fill Posterior (3M ESPE). The bite forces in
Newtons were measured initially and postoperatively for all teeth in habitual bite
force using a miniload cell. Cone-beam tomography imaging was performed, and
the Digital Imaging and Communication in Medice (.dcm) files were exported to
Mimics, 3-Matic (Materialise) and Patran (MSC Software) software to create a
patient-specific FEA models. Bite load was carry out using contact load applied
by antagonist teeth in two moments: without ETT and restoration: PI. 30.1/136.6;
PII. 34.3/133.4 and PIII. 47.9/124.1; and after restorative procedure: PI. 136.6;
PII. 133.4 and PIII. 124.1 N. Performing ETT and bulk fill resin composite
restoration the bite load increased 260% (36.7±11.6) to 131.9±17.8). The
restorations were evaluated after 2 years. Before rehabilitation the stresses
concentrated on weakened coronal dental structure and after rehabilitation they
were homogeneously transferred to root dentin, irrespective of the level of the
tooth structure loss. When the postoperatively bite load was applied on nontreated
tooth models, high stress concentration on weakened areas was verified.
The restorations performed perfectly after 2 years. The extensive caries with pulp
involvement affected negatively the bite load and increased the stress
concentration on weakened areas and at furcation favoring the tooth fracture. The
ETT and bulk fill resin composite restoration showed to be an efficient method for
rehabilitate the biomechanical performance of molar teeth of young patients
severely compromised structurally. / Dissertação (Mestrado)
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Modélisation de l’ablation radiofréquence pour la planification de la résection de tumeurs abdominales / Computational modeling of radiofrequency ablation for the planning and guidance of abdominal tumor treatmentAudigier, Chloé 14 October 2015 (has links)
L'ablation par radiofréquence (ARF) de tumeurs abdominales est rendue difficile par l’influence des vaisseaux sanguins et les variations de la conductivité thermique, compliquant la planification spécifique à un patient donné. En fournissant des outils prédictifs, les modèles biophysiques pourraient aider les cliniciens à planifier et guider efficacement la procédure. Nous introduisons un modèle mathématique détaillé des mécanismes impliqués dans l’ARF des tumeurs du foie comme la diffusion de la chaleur et la nécrose cellulaire. Il simule l’étendue de l’ablation à partir d’images médicales, d’après lesquelles des modèles personnalisés du foie, des vaisseaux visibles et des tumeurs sont segmentés. Dans cette thèse, une nouvelle approche pour résoudre ces équations basée sur la méthode de Lattice Boltzmann est introduite. Le modèle est d’abord évalué sur des données de patients qui ont subi une ARF de tumeurs du foie. Ensuite, un protocole expérimental combinant des images multi-modales, anatomiques et fonctionnelles pré- et post-opératoires, ainsi que le suivi de la température et de la puissance délivrée pendant l'intervention est présenté. Il permet une validation totale du modèle qui considère des données les plus complètes possibles. Enfin, nous estimons automatiquement des paramètres personnalisés pour mieux prédire l'étendu de l’ablation. Cette stratégie a été validée sur 7 ablations dans 3 cas cliniques. A partir de l'étude préclinique, la personnalisation est améliorée en comparant les simulations avec les mesures faites durant la procédure. Ces contributions ont abouti à des résultats prometteurs, et ouvrent de nouvelles perspectives pour planifier et guider l’ARF. / The outcome of radiofrequency ablation (RFA) of abdominal tumors is challenged by the presence of blood vessels and time-varying thermal conductivity, which make patient-specific planning extremely difficult. By providing predictive tools, biophysical models may help clinicians to plan and guide the procedure for an effective treatment. We introduce a detailed computational model of the biophysical mechanisms involved in RFA of hepatic tumors such as heat diffusion and cellular necrosis. It simulates the extent of ablated tissue based on medical images, from which patient-specific models of the liver, visible vessels and tumors are segmented. In this thesis, a new approach for solving these partial differential equations based on the Lattice Boltzmann Method is introduced. The model is first evaluated against clinical data of patients who underwent RFA of liver tumors. Then, a comprehensive pre-clinical experiment that combines multi-modal, pre- and post-operative anatomical and functional images, as well as the interventional monitoring of the temperature and delivered power is presented. This enables an end-to-end validation framework that considers the most comprehensive data set for model validation. Then, we automatically estimate patient-specific parameters to better predict the ablated tissue. This personalization strategy has been validated on 7 ablations from 3 clinical cases. From the pre-clinical study, we can go further in the personalization by comparing the simulated temperature and delivered power with the actual measurements during the procedure. These contributions have led to promising results, and open new perspectives in RFA guidance and planning.
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Personalization of Bone Remodelling Simulation Models for Clinical ApplicationsGutiérrez Gil, Jorge 15 January 2024 (has links)
[ES] El acceso a una atención sanitaria de alta calidad es un marcador importante del desarrollo de las sociedades humanas. Los aportes tecnológicos a la medicina han mostrado un potencial relevante para descubrir procedimientos efectivos a nivel preventivo, diagnóstico y terapéutico. En particular, los métodos computacionales permiten el procesamiento eficaz de datos médicos y, por tanto, pueden modelar sistemas biológicos complejos. Esto ha influido en el desarrollo de la Medicina Personalizada (MP) durante las últimas décadas, donde la obtención de conocimiento específico de cada caso permite realizar intervenciones a medida, todo ello a un coste de recursos accesible. La simulación de remodelación ósea es un campo prometedor en el contexto de la MP. Predecir un proceso de adaptación ósea en un caso concreto puede dar lugar a numerosas aplicaciones en el campo de las enfermedades óseas, tanto a nivel clínico como experimental. Mediante la combinación del Método de Elementos Finitos (FEM) y los algoritmos de remodelación ósea, es posible obtener modelos numéricos de un hueso específico a partir de datos médicos (por ejemplo, una tomografía computarizada). Todo ello puede dar lugar a una revolución en la medicina personalizada. / [CA] L'accés a una atenció sanitària d'alta qualitat és un marcador important del desenvolupament de les societats humanes. Les aportacions tecnològiques a la medicina han mostrat un potencial rellevant per a descobrir procediments efectius a nivell preventiu, diagnòstic i terapèutic. En particular, els mètodes computacionals permeten el processament eficaç de dades mèdiques i, per tant, poden modelar sistemes biològics complexos. Això ha influït en el desenvolupament de la Medicina Personalitzada (MP) durant les últimes dècades, on l'obtenció de coneixement específic de cada cas permet realitzar intervencions a mesura, tot això a un cost de recursos accessible. La simulació de remodelació òssia és un camp prometedor en el context de la MP. Predir un procés d'adaptació òssia en un cas concret pot donar lloc a nombroses aplicacions en el camp de les malalties òssies, tant a nivell clínic com experimental. Mitjançant la combinació del Mètode d'Elements Finits (*FEM) i els algorismes de remodelació òssia, és possible obtindre models numèrics d'un os específic a partir de dades mèdiques (per exemple, una tomografia computada). Tot això pot donar lloc a una revolució en la medicina personalitzada. / [EN] Access to high-quality healthcare is an important marker of the development of human societies. Technological contributions to medicine have shown relevant potential to discover effective procedures at a preventive, diagnostic and therapeutic level. In particular, computational methods enable efficient processing of medical data and can therefore model complex biological systems. This has influenced the development of Personalized Medicine (PM) over recent decades, where obtaining specific knowledge of each case allows for tailored interventions, all at an affordable resource cost. Simulation of bone remodeling is a promising field in the context of PM. Predicting a bone adaptation process in a specific case can lead to numerous applications in the field of bone diseases, both clinically and experimentally. By combining the Finite Element Method (FEM) and bone remodeling algorithms, it is possible to obtain numerical models of a specific bone from medical data (for example, a CT scan). All of this can lead to a revolution in personalized medicine. / Thanks to the Valencian funding programme FDGENT/2018, for providing economic resources to develop this long-term work. / Gutiérrez Gil, J. (2023). Personalization of Bone Remodelling Simulation Models for Clinical Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202059
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