Quantitative susceptibility mapping parameter optimization for basal nuclei iron depiction: A systematic analysis of...

Quantitative susceptibility mapping (QSM) is a valuable MRI technique for quantifying iron deposition in deep brain nuclei, such as the globus pallidus and putamen. However, the accuracy and image quality of QSM are strongly influenced by acquisition and post-processing parameters, including echo number and threshold, whose optimization has not been systematically investigated. Herein, this study aimed to comprehensively evaluate the effects of echo number (1-16) and threshold (0.01-0.20) on image quality, signal intensity, and magnetic susceptibility values in the basal nuclei across different age groups. Sixty healthy volunteers were divided into a young (20-30 years, the number of cases is 30) and an older group (50-60 years, the number of cases is 30); QSM images were reconstructed with various parameters and evaluated subjectively by two radiologists using a 5-point scale, while susceptibility and signal intensity were measured in target regions. Results demonstrated that image quality was optimal at echo numbers 5-12 and thresholds 0.02-0.06, with susceptibility values exhibiting a significant negative correlation to both parameters. Consistency comparisons against default settings showed stable quantification within echo numbers 5-11 for the young group and 5-10 (GP)/6-11 (PU) for the older group, as well as within thresholds of 0.04-0.08 (young) and 0.03-0.07 (older). In conclusion, echo number and threshold substantially affect QSM outcomes, and age-specific parameters are recommended: for younger adults, the echo number of 5 with the thresholds of 0.04-0.08, and for older adults, echo number 6 with the thresholds of 0.04-0.07, to achieve consistent iron quantification and superior depiction of basal nuclei.