Comparative quantitative analysis of iron deposition in gray matter nuclei in healthy human brains using 7 T and 3 T MRI

PEI Xun; ZHANG Xue; BAI Xiaoyan; LI Yu'an; CHEN Tong; ZHAO Yuanbin; SUI Binbin

doi:10.19300/j.2024.L21598

Abstract：Objective To compare the differences in iron deposition within deep gray matter nuclei of the normal human brain using quantitative susceptibility mapping(QSM)at 7 T and 3 T magnetic field strengths.Methods Ten healthy young volunteers without neurological diseases were prospectively recruited,with an average age of(22±3)years.QSM data were collected using 7 T and 3 T MRI scans.The STI-suite algorithm was used for QSM post-processing.Twelve regions of interest(ROIs),including the bilateral red nucleus,substantia nigra,globus pallidus,putamen,caudate nucleus head,and thalamus,were manually delineated,and the magnetic susceptibility values of the gray matter nuclei were measured.The nuclei were divided into high-susceptibility and low-susceptibility groups based on the average susceptibility value of all nuclei on 7 T QSM.Paired t-tests or Wilcoxon rank-sum tests were used to compare the susceptibility differences of the same nuclei at the two magnetic field strengths.Linear regression models and Bland-Altman plots were used to analyze the fit and consistency of quantitative susceptibility values of different nuclei at the two magnetic field strengths.Results The overall magnetic susceptibility values of the gray matter nuclei measured at 3 T were higher than those at 7 T(P＜0.05).In the high-susceptibility group(red nucleus,substantia nigra,globus pallidus),the susceptibility values of each nucleus and the overall results measured at 3 T were higher than those at 7 T(P＜0.05).In the low-susceptibility group(caudate nucleus,putamen,thalamus),there was no statistically significant difference in susceptibility values between the two field strengths for each nucleus and the overall results(P＞0.05).Linear regression results showed a good fit for overall susceptibility values of nuclei(R2=0.954)and susceptibility values of each nucleus(R2=0.803-0.936)at the two field strengths.Bland-Altman plot analysis showed higher consistency in susceptibility values of each nucleus in the low-susceptibility group compared to the high-susceptibility group.The susceptibility values between the two field strengths of low-susceptibility group showed higher fit(R2=0.995)and consistency than the high-susceptibility group(R2=0.862).Conclusion There is high consistency in the susceptibility values of low-susceptibility nuclei measured at 7 T and 3 T field strengths,while there is greater variation in high-susceptibility nuclei.The influence of field strength on quantitative iron deposition in tissues with different susceptibility should be considered when performing QSM assessments.