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Abstract(s)
A Espectroscopia por Ressonância Magnética (ERM) é a única técnica não-invasiva e não radioactiva que permite investigar o metabolismo dos tecidos vivos. A ERM do protão 1H, que proporciona a maior sensibilidade de todos os núcleos visíveis por RM, é um método capaz de detectar e quantificar biomoléculas cardíacas específicas. No entanto, os metabolitos estudados com ERM estão presentes em concentrações que são várias ordens de grandeza inferiores às dos protões da água, o que faz com que a 1H-ERM não seja ainda utilizada na prática clínica devido a desafios metodológicos. Muitos estudos têm vindo a ser realizados a fim de melhorar os meios de quantificação e o BMRU tem estado na vanguarda do desenvolvimento de uma plataforma de análise de dados de ERM. Portanto, este projecto tem como objectivo desenvolver uma rotina capaz de ler dados de ERM da Siemens no formato específico TWIX e realizar uma análise piloto sobre dados 1H-ERM provenientes de coração humano.
O trabalho realizado comtemplou diversas etapas. Inicialmente foi feito um estudo detalhado em relação aos ficheiros TWIX da Siemens, recorrendo a um algoritmo escrito em Matlab que tem o propósito de ler este tipo de ficheiro. De seguida, foi desenvolvida em IDL (Interactive Data Language) a rotina para leitura de ficheiros TWIX da Siemens que devolve os dados de ERM não processados no domínio do tempo. Foram analisados em jMRUI 14 conjuntos de dados de Espectroscopia por Resonância Magnética 1H relativos a coração humano, no domínio do tempo, usando Lorentzian line shape, e comparou-se os resultados para o sinal de água com os obtidos anteriormente por Rial et al. (2011), para os mesmos dados. Os mesmos espectros foram re-analisados utilizando o mesmo modelo mas no domínio da frequência, utilizando o software bmru_mrsw, onde foi incorporada a rotina desenvolvida. Finalmente foram analisados os mesmos conjuntos de dados usando Voigt line shape, no domínio da frequência, novamente com o software bmru_mrsw.
Houve conformidade entre os resultados obtidos na análise dos dados de ERM com o sofware jMRUI e os publicados por Rial et al. (2011), com um coeficiente de correlação de 0,997. A diferença média entre as duas medições do sinal de água foi de 0,06, segundo o gráfico Bland-Altman. A análise dos dados, no domínio da frequência, com o software bmru_mrsw demonstrou concordância com os resultados obtidos pelo jMRUI, tendo-se obtido um coeficiente de correlação de 0,716 entre os resultados. A quantificação do sinal de água utilizando Voigt line shape, no software bmru_mrsw, demonstrou diminuição dos resíduos gerados.
Deste modo, foi possível com este projecto a criação de uma rotina capaz de ler data de Espectroscopia por Ressonância Magnética da Siemens no formato específico TWIX. Esta rotina conferiu ao software bmru_mrsw compatibilidade com este formato de ficheiros, tendo deste modo contribuído para o aperfeiçoamento das técnicas de quantificação de sinais de espectroscopia. A potencialidade da abordagem de análise no domínio do tempo e frequência foi também demonstrada. Os objectivos propostos neste projecto foram alcançados com sucesso, podendo este ter contribuído para o papel da Espectroscopia por Ressonância Magnética no campo da cardiologia clínica.
Magnetic Resonance Spectroscopy (MRS) is the only non-invasive and non-radiation technique for investigating the metabolism of living tissue. Proton (1H)-MRS, which provides the highest sensitivity of all MR-visible nuclei, is a method capable of detecting and quantifying specific cardiac biomolecules. However, metabolites studied with MRS are present in concentrations that are several orders of magnitude lower than those of water protons, which make 1H-MRS not being used yet in clinical practice, due to fundamental methodological challenges. Many studies are being carried out in order to increasingly improve the means of quantification and BMRU has been at the forefront of developing a novel analysis framework for MRS data. Therefore, this project aims to develop a read-in routine capable of reading Siemens MRS data in the specific TWIX format and to conduct a pilot analysis on a human cardiac 1H Siemens MRS data. The work carried out contemplated several phases. Initially a detailed study regarding the Siemens TWIX files was conducted, using an algorithm written in Matlab that aims to read this type of file. Then, it was developed in IDL (Interactive Data Language) the read-in routine for Siemens TWIX files that returns the unprocessed time domain MRS data. 14 human cardiac 1H-MRS data sets were analyzed in the time domain using Lorentzian line shape in jMRUI, and the results for the water signal were compared with those previously obtained by Rial et al. (2011), for the same data. The same unsuppressed spectra were re-analyzed using the same model but in the frequency domain, using the software bmru_mrsw, where had been incorporated the developed read-in routine. Finally the same data sets were analyzed using Voigt line shape, in the time domain frequency domain, again with software bmru_mrsw. There was agreement between the obtained results in the analysis of MRS data with jMRUI software and the ones published by Rial et al. (2011), with a correlation coefficient of 0.997. The mean difference between the two measurements for the water signal was 0.06, according to the Bland-Altman plot. The data analysis with bmru_mrsw software in the frequency domain, agreed with the results obtained by jMRUI, yielding a correlation coefficient of 0.716. Quantification of the water signal using Voigt line shape in bmru_mrsw software originated lower residues. Thus, it was possible with this project to create a routine able to read the Siemens Magnetic Resonance Spectroscopy data in the specific format TWIX. This routine conferred to the bmru_mrsw software compatibility with this file format, and thereby contributed to the improvement of techniques for quantifying spectroscopy signals. The capability of the time domain frequency domain fitting approach was also demonstrated. The proposed objectives in this project were successfully achieved, and the project may has contributed to the role of Magnetic Resonance Spectroscopy in clinical cardiology.
Magnetic Resonance Spectroscopy (MRS) is the only non-invasive and non-radiation technique for investigating the metabolism of living tissue. Proton (1H)-MRS, which provides the highest sensitivity of all MR-visible nuclei, is a method capable of detecting and quantifying specific cardiac biomolecules. However, metabolites studied with MRS are present in concentrations that are several orders of magnitude lower than those of water protons, which make 1H-MRS not being used yet in clinical practice, due to fundamental methodological challenges. Many studies are being carried out in order to increasingly improve the means of quantification and BMRU has been at the forefront of developing a novel analysis framework for MRS data. Therefore, this project aims to develop a read-in routine capable of reading Siemens MRS data in the specific TWIX format and to conduct a pilot analysis on a human cardiac 1H Siemens MRS data. The work carried out contemplated several phases. Initially a detailed study regarding the Siemens TWIX files was conducted, using an algorithm written in Matlab that aims to read this type of file. Then, it was developed in IDL (Interactive Data Language) the read-in routine for Siemens TWIX files that returns the unprocessed time domain MRS data. 14 human cardiac 1H-MRS data sets were analyzed in the time domain using Lorentzian line shape in jMRUI, and the results for the water signal were compared with those previously obtained by Rial et al. (2011), for the same data. The same unsuppressed spectra were re-analyzed using the same model but in the frequency domain, using the software bmru_mrsw, where had been incorporated the developed read-in routine. Finally the same data sets were analyzed using Voigt line shape, in the time domain frequency domain, again with software bmru_mrsw. There was agreement between the obtained results in the analysis of MRS data with jMRUI software and the ones published by Rial et al. (2011), with a correlation coefficient of 0.997. The mean difference between the two measurements for the water signal was 0.06, according to the Bland-Altman plot. The data analysis with bmru_mrsw software in the frequency domain, agreed with the results obtained by jMRUI, yielding a correlation coefficient of 0.716. Quantification of the water signal using Voigt line shape in bmru_mrsw software originated lower residues. Thus, it was possible with this project to create a routine able to read the Siemens Magnetic Resonance Spectroscopy data in the specific format TWIX. This routine conferred to the bmru_mrsw software compatibility with this file format, and thereby contributed to the improvement of techniques for quantifying spectroscopy signals. The capability of the time domain frequency domain fitting approach was also demonstrated. The proposed objectives in this project were successfully achieved, and the project may has contributed to the role of Magnetic Resonance Spectroscopy in clinical cardiology.