Development of a methodology for identification of cardiac region in images of electrical impedance tomography of pulmonary perfusion by means of wavelet transform / Desenvolvimento de uma metodologia para identificação de região cardíaca em imagens de tomografia de impedância elétrica de perfusão pulmonar por meio da transformada wavelet

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Electrical Impedance Tomography (EIT) is an imaging technique, still in development, which allows imaging of the distribution of conductivity in a cross section of an object under analysis from electrical measures made on its surface. Despite its benefits and advantages over other imaging techniques, its images still do not offer a good spatial resolution. One of the biggest challenges in EIT thorax images is the treatment of the lung perfusion because the perspectives for clinical use are numerous. Thus, there is a great interest in improving the localization of its main organs. In order to improve the anatomical resolution was developed a methodology for identification of cardiac region in images of electrical impedance tomography of pulmonary perfusion by means of wavelet transform, using EIT images of pigs. Some preliminary studies of different approaches were performed in order to identify those characteristics that would indicate intrinsic similarities or differences among the pixels of different anatomical regions. These studies propitiated the development of five methods based on wavelet transform. A first set of experiments, performed in a single pig, was used in developing and improving of the methods. Subsequently, other experiments, involving four pigs in different physiological conditions, were performed to evaluate the performance of these methods. The wavelet perfusional images were compared with the perfusional images obtained by the method of injection of a hypertonic solution, considered as the perfusional reference standard images. Amongst the five developed methods, the best of them was selected as the wavelet methodology proposed by this work. It was capable to identify the heart region of five pigs under different physiological conditions, demonstrating to robustness and very satisfactory results, not only in quantitative terms, with an average area of the ROC curve of 0.86, but also in the quality of the images, where the contours delimiting the cardiac region were well defined and of circular format, according to what was expected. Therefore, the main objective of this work, that was to improve the spatial resolution of EIT images of pulmonary perfusion, was reached with excellent results and additional benefits such as the possibility of its implementation in EIT equipments for monitoring thorax and thus collaborate in improving of medical decision support systems in critical environments, as for example the Intensive Care Units (ICUs).

ASSUNTO(S)

electric impedance sistema de apoio a decisões clínicas tomography perfusion clinical decision support system perfusão unidades de terapia intensiva coração tomografia pulmão heart intensive care units impedância elétrica lung

ACESSO AO ARTIGO

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