Optimized magnetic resonance spectroscopy of 2-hydroxyglutarate
Master thesis
Permanent lenke
https://hdl.handle.net/11250/3139350Utgivelsesdato
2024-06-03Metadata
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- Master theses [79]
Sammendrag
In recent years, non-invasive detection of 2-hydroxyglutarate (2HG) using 1H − MRS has emerged as a promising method for differentiating IDH mutant and wild-type brain tumors. However, reliable detection and quantification of 2HG remain challenging due to its MR spectrum, which consists of five non-interchangeable protons at 4.02 ppm, 2.27 ppm, 2.22 ppm, 1.98 ppm, and 1.83 ppm, complex J-coupling patterns, and strong overlap with signals from other brain metabolites. There is currently no consensus on the optimal pulse sequence, spectral editing techniques, and corresponding spectral parameters for 2HG detection. Short-TE PRESS, MEGA-PRESS, sLASER, and MEGA-sLASER have been identified as the most promising pulse sequences. However, recommendations for echo times and other spectral parameters to optimize 2HG quantification remain unclear, particularly given the impact of higher-order J-couplings, which vary with magnetic field strength.
This thesis investigates the spectroscopic parameters required for optimal detection of 2HG by measuring the spectra of 2HG phantoms at magnetic field strengths of 60 MHz, 500 MHz, and 600 MHz, as well as using a 3T GE scanner for phantom studies. The study examines different pulse sequences (with and without spectral editing) and varying echo times to thoroughly explore the complex J-coupling patterns and their dependence on echo time and magnetic field strength. The results provide insights into choosing the optimal 1H − MRS method for 2HG quantification and how to determine appropriate basis sets for spectral fitting.
Comprehensive spectral analysis tools, including TopSpin, LCModel, and Osprey, are used to evaluate the data, and calibration curves are developed for 2HG concentrations in both isolated and BRAINO solutions. The study also employs a 3D-printed phantom to validate experimental setups at the 3 T GE scanner and explores in vivo spectra to correlate findings with clinical observations.
The findings suggest optimized spectroscopic parameters for the detection of 2HG and propose potential improvements for future research. This work enhances the understanding of MRS in detecting the metabolite 2HG, offering valuable insights for clinical applications in the differentiation of brain tumors.