Influence of echo time in quantitative proton MR spectroscopy using LCModel.

Area of Science:

• Medical Imaging
• Neuroscience
• Biophysics

Background:

• Proton magnetic resonance spectroscopy (MRS) is crucial for non-invasive metabolite quantification.
• LCModel is a widely used software for analyzing MRS data.
• Recommended echo time (TE) settings are critical for accurate spectral quantification.

Purpose of the Study:

• To investigate the impact of extended echo times (TE) on quantitative analysis using LCModel.
• To compare LCModel results with a T2-corrected reference method under varying TE conditions.

Main Methods:

• Proton MRS was performed on a 3T system in 5 healthy volunteers and 11 glioma patients.
• Data were acquired at echo times (TE) of 72ms, 144ms, and 288ms.
• Metabolite quantification was done using LCModel and compared to T2-corrected values.

Main Results:

• LCModel overestimated metabolite quantification by up to 6.8-fold in healthy volunteers at longer TEs compared to the reference method.
• The overestimation varied significantly between metabolites and was also observed in glioma patients.
• Increased TE led to larger ratios and greater inter-individual variability in quantitative values.

Conclusions:

• Extended echo times (TE) beyond recommended values can lead to significant overestimation of metabolite quantification by LCModel.
• LCModel's inability to fully compensate for signal attenuation at longer TEs causes this overestimation.
• Reduced reliability of LCModel quantitative values should be considered in clinical practice when longer TEs are used.