Development of a reade-in routine to aid quantitative analysis of cardiac 1H-MRS Data

Abstract

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.

Date of Award	2014
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Jürgen Schneider (Supervisor)