1H MRS and MRSI: analysis of acquisition parameters and improvement of various clinical applications

MRS and MRSI are valuable tools for diagnosis and staging of several pathologies, much before become detectable by other imaging methods. Combined with other imaging techniques in an advancing modality like MRI offer the ability to estimate accurately the overall condition of the examined tissue. MRS and MRSI could be potentially suited for repeated monitoring since it entails no exposure to ionizing radiation. Incorporation of these tools in clinical practice is, however, limited due to the considerable amount of user intervention. In this study various acquisition parameters and their effect in spectrum quality are investigated. A series of experiments were conducted, using a manufacturer´s spectroscopy phantom, to assess the quality of various spectroscopic imaging techniques. The effectiveness of the available water and lipid suppression techniques and their compatibility with other parameters were also investigated. The stability of the equipment, the appearance of artifacts and the reproducibility of the results were also examined to obtain conclusions for the interaction of acquisition parameters. All the data were processed with jMRUI 2.2 to analyze various aspects of the measurements, quantify parameters such as signal to noise ratio (SNR) and full width at half maximum (FWHM) and extract useful conclusions for the function of these methods. The experience acquired from the conducted experiments was applied in improvement of clinical applications (prostate, brain and muscle examinations) by significantly improving the spectrum quality, SNR (up to 75%), spatial resolution and in most cases reducing exam times (up to 60%).