Este trabalho teve como objetivo estudar um caso específico de epilepsia refratária causada por uma má formação no tecido cerebral, denominada displasia cortical focal (DCF). Por ser uma má formação no cérebro, suas consequências aparecem desde a infância, em que ela, a DCF, é a principal causadora das epilepsias de caso refratário. O mapeamento da região com DCF geralmente é feito por meio de imagens de ressonância magnética em conjunto com outras técnicas, como, por exemplo, o PET (positron emission tomography), o EEG (eletroencefalograma) intracraniano, entre outras. Contudo, por serem técnicas muito caras, de difícil realização ou muito invasivas, e por sabermos que as regiões displásicas possuem uma rigidez diferente da do restante do cérebro, foi proposto nesta dissertação o estudo desses casos utilizando uma técnica barata, simples, não invasiva e sensível à rigidez tecidual, a elastografia por ultrassom, na qual, para causar a deformação do tecido cerebral, foram usadas próprias artérias internas do cérebro. Para tal estudo, criamos um algoritmo de processamento de dados com uma interface gráfica GUI (graphical user interface) capaz de mudar os parâmetros de processamento e ver seus resultados em tempo real. Em seguida, esse algoritmo foi estudado em um ambiente controlado em material mimetizador de tecido biológico (phantom), no qual construímos um bloco de 10 x 10 x 12cm3, preenchido com material que mimetiza as propriedades mecânicas e acústicas do tecido mole e inserimos nele uma bexiga canudo preenchida com um uido simulador de sangue e uma inclusão mais rígida do que a base do material, posicionada acima do canudo. Foi utilizado, também, um acionador mecânico pulsátil para simular a pulsação mecânica equivalente à pulsação sanguínea da artéria cerebral. Foram feitas imagens elastográcas e de velocidade utilizando somente a deformação causada pelo deslocamento da bexiga, no interior do phantom, e, através de uma transformada de Fourier, foi calculado o período de pulsação da bexiga. Vimos que as imagens elastográcas e de velocidade foram capazes de localizar a inclusão, e o processamento temporal pode nos mostrar com precisão a frequência de pulsação da bexiga canudo. Finalizada essa etapa laboratorial, zemos o mesmo procedimento, porém in vivo, para dois casos: um com DCF tipo III-B, no qual não enxergávamos nada no modo B; e outro com tipo II-B, no qual foi observado uma diferença de impedância mecânica pelo modo B. As imagens foram coletadas durante o procedimento cirúrgico pelo próprio cirurgião usando um transdutor microconvexo acoplado a uma plataforma de ultrassom, modelo Sonix RP, e processadas num segundo momento. Vimos, no primeiro caso, pelas imagens elastográcas, as regiões mais rígidas, supostamente displásicas, que não estavam aparecendo no modo B e, no segundo caso, uma região maior do que a apresentada no modo B. Nossos resultados das medidas de frequência da pulsação arterial, para ambas as situações, 61; 5BPM e 91BPM, caram bastante próximos do valor medido com o eletrocardiograma durante a coleta do sinal, 65BPM e 94BPM, respectivamente. Por meio dos resultados da análise histológica, pudemos conrmar que o que estávamos enxergando com nosso programa era realmente uma região displásica. Dessa forma, concluímos que nosso algoritmo funcionou bem para esses casos clínicos. / The mainly goal of this work was to study a specic case of refractory epilepsy generated by a malformation in the brain tissue, called focal cortical dysplasia (FCD). Due the fact it is a brain malformation its eects show up since the childhood where it is the principal epilepsy generator. The mapping of this region is usually made by magnetic resonance images with another technique, such as, for instance, the PET (position emition tomography), the EEG (electrocardiogram), and others. However, for the fact that these techniques are expensive, dicult to perform or invasive, and knowing that the dysplastic regions are stier than the regular brain tissue, it was proposed in this dissertation the use of ultrasound elastography as a cheaper, simpler and noninvasive image modality capable to detect dierences in the tissue stiness of the FCD region. To generate the strain in the brain tissue it was used the pulsation of the local arteries. To achieve our goal, we created a data processing algorithm in MATLAB with a graphic user interface (GUI) capable to change the processing parameters to see its results in real time. This algorithm was tested in phantom using a block of tissue mimicking material (10 x 10 x 12 cm3). A balloon of latex led with a blood mimicking uid was immersed in the middle of the phantom and a cylindrical inclusion of 1 cm of diameter was immersed above the balloon. The bulb of the balloon was keep outside of the phantom to be mechanically pressured by a dedicated magnetic actuator, simulating the mechanical pulsation of the brain arteries. The velocity and elastography images were studied using just the strain caused by the displacement of the wall of the balloon tube inside the phantom. The period of pulsation was precisely calculated from these images. After that, we did the same procedure in two in vivo cases: one with FCD type III-B; and the other with FCD type II-B. All our intraoperative images were acquired for the surgeons using a micro convex transducer linked to an Ultrasound platform (Sonix RP) and, then, processed o-line. In the B mode scanning we didnât see any formation inside the brain for the rst case, and for the second, we did. In the elastographic images we saw a clearly stiffer region in the rst case that was invisible in the B mode; and for the second case, we saw a bigger stiffer region than we saw in the B mode imaging too. And for both results, the arteria pulsation frequency, 61.5 BPM and 91 BPM, were veryclose to the measured value collected in the electrocardiogram during the surgery, 65 BPM and 94 BPM, respectively. Analyzing the histological results we could conrm that what we were showing in our elastographic images were FCD, indeed. Thereby we concluded that our algorithm had worked in these clinical data.

This paper highlights two methods of examining the bovine pancreas by means of ultrasound, with a view to identifying advantages and disadvantages of the two techniques as well as testing and comparing their practicability. The goal is to evaluate the applicability of this intraoperative procedure to large animals - it is quite commonly used on humans - as well as present the resulting findings with regard to the ultrasonographic anatomy of the bovine pancreas. The sample consisted of 15 female beef cattle, none of which displayed evidence of any pancreatopathy based on their medical history, clinical examinations, and laboratory diagnostic testing. Transcutaneous and intraoperative sonographic examinations were performed on all 15 animals.

Este trabalho teve como objetivo estudar um caso específico de epilepsia refratária causada por uma má formação no tecido cerebral, denominada displasia cortical focal (DCF). Por ser uma má formação no cérebro, suas consequências aparecem desde a infância, em que ela, a DCF, é a principal causadora das epilepsias de caso refratário. O mapeamento da região com DCF geralmente é feito por meio de imagens de ressonância magnética em conjunto com outras técnicas, como, por exemplo, o PET (positron emission tomography), o EEG (eletroencefalograma) intracraniano, entre outras. Contudo, por serem técnicas muito caras, de difícil realização ou muito invasivas, e por sabermos que as regiões displásicas possuem uma rigidez diferente da do restante do cérebro, foi proposto nesta dissertação o estudo desses casos utilizando uma técnica barata, simples, não invasiva e sensível à rigidez tecidual, a elastografia por ultrassom, na qual, para causar a deformação do tecido cerebral, foram usadas próprias artérias internas do cérebro. Para tal estudo, criamos um algoritmo de processamento de dados com uma interface gráfica GUI (graphical user interface) capaz de mudar os parâmetros de processamento e ver seus resultados em tempo real. Em seguida, esse algoritmo foi estudado em um ambiente controlado em material mimetizador de tecido biológico (phantom), no qual construímos um bloco de 10 x 10 x 12cm3, preenchido com material que mimetiza as propriedades mecânicas e acústicas do tecido mole e inserimos nele uma bexiga canudo preenchida com um uido simulador de sangue e uma inclusão mais rígida do que a base do material, posicionada acima do canudo. Foi utilizado, também, um acionador mecânico pulsátil para simular a pulsação mecânica equivalente à pulsação sanguínea da artéria cerebral. Foram feitas imagens elastográcas e de velocidade utilizando somente a deformação causada pelo deslocamento da bexiga, no interior do phantom, e, através de uma transformada de Fourier, foi calculado o período de pulsação da bexiga. Vimos que as imagens elastográcas e de velocidade foram capazes de localizar a inclusão, e o processamento temporal pode nos mostrar com precisão a frequência de pulsação da bexiga canudo. Finalizada essa etapa laboratorial, zemos o mesmo procedimento, porém in vivo, para dois casos: um com DCF tipo III-B, no qual não enxergávamos nada no modo B; e outro com tipo II-B, no qual foi observado uma diferença de impedância mecânica pelo modo B. As imagens foram coletadas durante o procedimento cirúrgico pelo próprio cirurgião usando um transdutor microconvexo acoplado a uma plataforma de ultrassom, modelo Sonix RP, e processadas num segundo momento. Vimos, no primeiro caso, pelas imagens elastográcas, as regiões mais rígidas, supostamente displásicas, que não estavam aparecendo no modo B e, no segundo caso, uma região maior do que a apresentada no modo B. Nossos resultados das medidas de frequência da pulsação arterial, para ambas as situações, 61; 5BPM e 91BPM, caram bastante próximos do valor medido com o eletrocardiograma durante a coleta do sinal, 65BPM e 94BPM, respectivamente. Por meio dos resultados da análise histológica, pudemos conrmar que o que estávamos enxergando com nosso programa era realmente uma região displásica. Dessa forma, concluímos que nosso algoritmo funcionou bem para esses casos clínicos. / The mainly goal of this work was to study a specic case of refractory epilepsy generated by a malformation in the brain tissue, called focal cortical dysplasia (FCD). Due the fact it is a brain malformation its eects show up since the childhood where it is the principal epilepsy generator. The mapping of this region is usually made by magnetic resonance images with another technique, such as, for instance, the PET (position emition tomography), the EEG (electrocardiogram), and others. However, for the fact that these techniques are expensive, dicult to perform or invasive, and knowing that the dysplastic regions are stier than the regular brain tissue, it was proposed in this dissertation the use of ultrasound elastography as a cheaper, simpler and noninvasive image modality capable to detect dierences in the tissue stiness of the FCD region. To generate the strain in the brain tissue it was used the pulsation of the local arteries. To achieve our goal, we created a data processing algorithm in MATLAB with a graphic user interface (GUI) capable to change the processing parameters to see its results in real time. This algorithm was tested in phantom using a block of tissue mimicking material (10 x 10 x 12 cm3). A balloon of latex led with a blood mimicking uid was immersed in the middle of the phantom and a cylindrical inclusion of 1 cm of diameter was immersed above the balloon. The bulb of the balloon was keep outside of the phantom to be mechanically pressured by a dedicated magnetic actuator, simulating the mechanical pulsation of the brain arteries. The velocity and elastography images were studied using just the strain caused by the displacement of the wall of the balloon tube inside the phantom. The period of pulsation was precisely calculated from these images. After that, we did the same procedure in two in vivo cases: one with FCD type III-B; and the other with FCD type II-B. All our intraoperative images were acquired for the surgeons using a micro convex transducer linked to an Ultrasound platform (Sonix RP) and, then, processed o-line. In the B mode scanning we didnât see any formation inside the brain for the rst case, and for the second, we did. In the elastographic images we saw a clearly stiffer region in the rst case that was invisible in the B mode; and for the second case, we saw a bigger stiffer region than we saw in the B mode imaging too. And for both results, the arteria pulsation frequency, 61.5 BPM and 91 BPM, were veryclose to the measured value collected in the electrocardiogram during the surgery, 65 BPM and 94 BPM, respectively. Analyzing the histological results we could conrm that what we were showing in our elastographic images were FCD, indeed. Thereby we concluded that our algorithm had worked in these clinical data.

This paper highlights two methods of examining the bovine pancreas by means of ultrasound, with a view to identifying advantages and disadvantages of the two techniques as well as testing and comparing their practicability. The goal is to evaluate the applicability of this intraoperative procedure to large animals - it is quite commonly used on humans - as well as present the resulting findings with regard to the ultrasonographic anatomy of the bovine pancreas. The sample consisted of 15 female beef cattle, none of which displayed evidence of any pancreatopathy based on their medical history, clinical examinations, and laboratory diagnostic testing. Transcutaneous and intraoperative sonographic examinations were performed on all 15 animals.

Objectif: Lors de l’ablation de tumeurs cérébrales, la navigation chirurgicale est basée sur les examens IRM pré-opératoires. Or, la déformation per-opératoire du cerveau, appelée brain-shift, affecte cette navigation. Dans cette thèse, une méthode de compensation du brain-shift intégrable dans un processus clinique est présentée.Méthode: Avant la chirurgie, un modèle biomécanique patient-spécifique est construit à partir des images pré-opératoires. Il intègre la géométrie des tissus mous mais également des vaisseaux. Pendant l’opération, des acquisitions échographiques localisées sont réalisées directement en contact avec le cerveau. Les modalités mode B et Doppler sont enregistrées simultanément, permettant respectivement l’extraction des vaisseaux et de l’empreinte de la sonde. Une simulation biomécanique est ensuite jouée pour compenser le brain-shift. Différentes contraintes sont appliquées au modèle de cerveau afin de modéliser les contacts avec la dure-mère, recaler les vaisseaux pré- et per-opératoires et contraindre la surface corticale avec l’empreinte de la sonde. Lors de la résection de tumeurs profondes, la trajectoire chirurgicale est également contrainte au sein de la cavité réséquée afin de retrouver les déformations latérales induites par l’écartement des tissus. Les images IRM pré-opératoires ont finalement mises à jour suivant le champ de déformation du modèle biomécanique.Résultats: La méthode a été évaluée quantitativement à partir de données synthétiques et cliniques de cinq patients. De plus, l’alignement des images a également été apprécié qualitativement, au regard des attentes des neurochirurgiens. Des résultats très satisfaisants, de l’ordre de 2 mm d’erreur, sont obtenus à l’ouverture de la dure-mère et dans le cas de résection de tumeurs en surface. Lors de la résection de tumeurs profondes, si la trajectoire chirurgicale permet de retrouver une grande partie des déformations induites par l’écartement des tissus, plusieurs limitations dues au fait que cette rétraction ne soit pas effectivement simulée sont montrées.Conclusion: Cette thèse propose une nouvelle méthode de compensation du brain-shit efficace et intégrable au bloc opératoire. Elle aborde de plus le sujet peu traité de la résection, en particulier de tumeurs profondes. Elle présente ainsi une étape supplémentaire vers un système optimal en neurochirurgie assistée par ordinateur. / Purpose: During brain tumor surgery, planning and guidance are based on preoperative MR exams. The intraoperative deformation of the brain, called brain-shift, however affect the accuracy of the procedure. In this thesis, a brain-shift compensation method integrable in a surgical workflow is presented.Method: Prior to surgery, a patient-specific biomechanical model is built frompreoperative images. The geometry of the tissues and blood vessels is integrated. Intraoperatively, navigated ultrasound images are performed directly in contact with the brain. B-mode and Doppler modalities are recorded simultaneously, enabling the extraction of the blood vessels and probe footprint, respectively. A biomechanical simulation is then executed in order to compensate for brain-shift. Several constraints are imposed to the biomechanical model in order to simulate the contacts with the dura mater, register the pre- and intraoperative vascular trees and constrain the cortical surface with the probe footprint. During deep tumors resection, the surgical trajectory is also constrained to remain inside the cavity induced by the resected tissues in order to capture the lateral deformations issued from tissues retraction. Preoperative MR images are finally updated following the deformation field of the biomechanical model.Results: The method was evaluated quantitatively using synthetic and clinical data. In addition, the alignment of the images was qualitatively assessed with respect to surgeons expectations. Satisfactory results, with errors in the magnitude of 2 mm, are obtained after the opening of the dura mater and for the resection of tumors close to the cortical surface. During the resection of deep tumors, while the surgical trajectory enable to capture most of the deformations induced by tissues retraction, several limitations reflects the fact that this retraction is not actually simulated.Conclusion: A new efficient brain-shift compensation method that is integrable in an operating room is proposed in this thesis. The few studied topic of the resection, and more specifically of deep tumors, is also addressed. This manuscript thus present an additional step towards an optimal system in computer assisted neurosurgery.