Alinhamento de imagens de esclerose múltipla

Nos doentes com esclerose múltipla (EM), a imagiologia por Ressonância Magnética (RM), apesar de não ser uma técnica imagiológica específica para esta doença, permite melhorar a capacidade de diagnóstico e acompanhar a evolução das lesões associadas. Assim, os médicos especialistas são frequentemente confrontados com diversas imagens por RM, quer obtidas em instantes distintos quer adquiridas segundo condições diferentes, para avaliar e comparar cargas de lesões. Contudo, nas avaliações e comparações manuais, além de demoradas e tediosas, residem sempre numerosas fontes de erro, o que origina resultados não confiáveis e repetíveis. Desta forma, para melhorar a análise das imagens, é frequente proceder ao seu alinhamento prévio. O principal objectivo deste trabalho consiste em avaliar o desempenho de dois algoritmos no alinhamento automático das estruturas representadas em imagens cerebrais de doentes com EM, obtidas através de RM, para o acompanhamento do progresso das lesões associadas

Evaluation of the results of orthodontic treatment by non-rigid image registration and deformation-based morphometry

The goal of this research was to find out, whether the non-rigid registration of dental casts can be used in the evaluation of orthodontic treatment and to develop a program, which would at least partially automatize the evaluation process of images. The aim was also to experiment the evaluation of three-dimensional models of the casts. This research was delimited to cover only the evaluation of malocclusions within the dental arch. The relationships between the dental arches were not considered. This thesis was done in the University of Vaasa at the Department of Electrical Engineering and Energy Technology as a part of the HammasSkanneri research project, whose aim is to automatize the digitization and archiving of dental casts. This research used two-dimensional images of dental casts which were taken of orthodontically treated patients before and after orthodontic treatment. Non-rigid registration was performed by using a registration tool of Fiji software. The evaluation of the accuracy of the registration was performed by measuring distances between manually inserted landmarks, and by comparing the linear and angular parameters of the registered images and the original target images. The displacements of the teeth were approximated with the help of deformation-based morphometry. The accuracy of registration is within reasonable error limits, if the image is taken straight from above of the cast and the registration is performed with the help of landmarks inserted by a human. Estimation of the changes showed that the movement of teeth can be coarsely measured by using deformation-based morphometry based on change estimates that resemble the Jacobian estimates. A set of programs, which partially automatize the evaluation of the accuracy and the changes, were developed. Three-dimensional imaging of the casts was unsuccessful, and thus the development of 3D evaluation system was left as a future research topic.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Acceptance Test of a Commercially Available Software for Automatic Image Registration of Computed Tomography (CT), Magnetic Resonance Imaging (MRI) And 99mTc-methoxyisobutylisonitrile (MIBI) Single-Photon Emission Computed Tomography (SPECT) Brain Images

This note describes a method to characterize the performances of image fusion software (Syntegra) with respect to accuracy and robustness. Computed tomography (CT), magnetic resonance imaging (MRI), and single-photon emission computed tomography (SPECT) studies were acquired from two phantoms and 10 patients. Image registration was performed independently by two couples composed of one radiotherapist and one physicist by means of superposition of anatomic landmarks. Each couple performed jointly and saved the registration. The two solutions were averaged to obtain the gold standard registration. A new set of estimators was defined to identify translation and rotation errors in the coordinate axes, independently from point position in image field of view (FOV). Algorithms evaluated were local correlation (LC) for CT-MRI, normalized mutual information (MI) for CT-MRI, and CT-SPECT registrations. To evaluate accuracy, estimator values were compared to limiting values for the algorithms employed, both in phantoms and in patients. To evaluate robustness, different alignments between images taken from a sample patient were produced and registration errors determined. LC algorithm resulted accurate in CT-MRI registrations in phantoms, but exceeded limiting values in 3 of 10 patients. MI algorithm resulted accurate in CT-MRI and CT-SPECT registrations in phantoms; limiting values were exceeded in one case in CT-MRI and never reached in CT-SPECT registrations. Thus, the evaluation of robustness was restricted to the algorithm of MI both for CT-MRI and CT-SPECT registrations. The algorithm of MI proved to be robust: limiting values were not exceeded with translation perturbations up to 2.5 cm, rotation perturbations up to 10° and roto-translational perturbation up to 3 cm and 5°

Avoiding the heart : about optimising whole breast irradiation

Preclinical and clinical studies reveal that left-sided breast cancer radiotherapy is associated with an increased rate of major coronary events. Consequently, when irradiating women with left-sided breast cancer, specific measures should be taken to decrease the heart dose as much as possible and to avoid radiation-induced coronary artery disease. This thesis focuses on several strategies to optimise the radiation treatment for patients with left-sided breast cancer. With respect to whole breast irradiation we concluded that: __ the routine use of MR images in addition to the CT scan, when delineating either the glandular breast tissue or the lumpectomy cavity, does not have added value. __ tangential IMRT technique combined with a breath-hold technique should be the treatment technique of choice for left-sided breast cancer. __ a breath-hold technique should and can be used in all left-sided breast cancer patients, regardless of age and breast size. __ breath-hold in left-sided whole breast radiotherapy results in a less pronounced increase of coronary calcium score and, hence, could result in less radiation-induced cardio vascular damage.UBL - phd migration 201