Quantitative susceptibility mapping study of deep gray matter iron content in glioma patients

Iron is associated with the pathophysiology of gliomas. The measurement of brain iron levels plays a vital role in defining the pathophysiologic changes caused by gliomas. This study aimed to analyze the effect of gliomas with different histopathology and molecular characteristics on deep gray matter (DGM) iron content and the relationship between DGM iron content and cognition in glioma patients (PT).

In this retrospective study, we included 81 PT, categorized according to different histopathology and molecular characteristics, and 30 age- and gender-matched healthy controls (HC). Brain quantitative susceptibility mapping (QSM) maps were computed from three-dimensional (3D) multi-echo gradient-echo data using Laplacian-based phase unwrapping, a variational sharpening (V-SHARP) background field correction and the streaking artifacts reduction (STAR)-QSM method. ITK-SNAP was used to measure the susceptibility values reflecting the iron content in the regions of interest. Differences in DGM magnetic susceptibility between groups were compared. Pearson's correlation analysis assessed the relationship between DGM magnetic susceptibility and Montreal Cognitive Assessment (MoCA).

Compared to HC, PT showed higher DGM magnetic susceptibility. QSM analysis exhibited higher DGM magnetic susceptibility in high-grade gliomas (HGG) than low-grade gliomas (LGG). Isocitrate dehydrogenase (IDH) wild-type gliomas showed higher magnetic susceptibility than IDH mutant-type in the putamen [IDH mutant-type: interquartile range (IQR), 0.052, 0.019 ppm vs. IDH wild-type: IQR, 0.062, 0.015 ppm, P=0.015]. A higher Ki-67 index also correlated with higher magnetic susceptibility in the putamen (high Ki-67 index group: IQR, 0.063, 0.019 ppm vs. low Ki-67 index group: IQR, 0.052, 0.016 ppm, P=0.005). The PT group had significantly lower MoCA scores than the HC group (patients group vs. HC group: 22.30±4.92 vs. 24.70±2.20, P=0.021). There was a negative correlation between MoCA scores and DGM magnetic susceptibility.

The DGM iron content, as measured by QSM, was higher in PT than in HC and correlated with tumor grade. Cognitive decline is associated with increased DGM iron content in PT. The DGM iron content could be a potential biomarker in glioma differentiation and prognosis.