Objective:To investigate the relationship among iron content, volume and drainage venous oxygen saturation (SvO 2) in deep gray matter nuclei of healthy people using quantitative susceptibility mapping (QSM). Methods:The study was a cross-sectional study. A total of 126 healthy volunteers were prospectively enrolled in the community in Tianjin from June 2019 to December 2023, and 57 males and 69 females, aged 48±15 years. All healthy volunteers underwent MRI examinations to get STrategically Acquired Gradient Echo images, then it was post-processed to obtain T 1 weighted enhanced images, QSM maps and the maximum intensity projection images. In QSM maps, caudate nucleus (CN), putamen (PUT), globus pallidus (GP), thalamus (THU), subthalamic nucleus (STN), substantia nigra (SN) and red nucleus (RN) were semi-automatically segmented to calculate the iron content and volume using SPIN software. Four bilateral deep cerebral veins regions of interest, including septum pellucidum veins, thalamostriate veins, internal cerebral veins and basilar veins, were manually delineated on the maximum intensity projection images of QSM to obtain venous magnetic sensitivity. The venous magnetic sensitivity was calculated as SvO 2. To observe the age-related trend of SvO 2, iron content and volume, the partial correlation analysis was conducted. The relationships between iron content, volume and SvO 2 were explored using the partial correlation analysis. To explore the potential effects of SvO 2 between iron content and volume in deep gray matter, the mediation analysis was utilized. Results:The relationships between the SvO 2 of thalamostriate veins ( r=0.23, P=0.018), basilar veins ( r=0.27, P=0.004) and age were positive. The relationships between the SvO 2 of internal cerebral veins and the iron contents of CN ( r=?0.25, P=0.042) and PUT ( r=?0.33, P<0.001) were negative. The relationships between the SvO 2 of basilar veins and the iron contents of STN ( r=?0.25, P=0.042) and SN ( r=?0.24, P=0.045) were negative. The relationships between iron content and volume including CN ( r=0.46, P<0.001), PUT ( r=0.20, P=0.027), GP ( r=0.76, P<0.001), STN ( r=0.87, P<0.001), SN ( r=0.90, P<0.001), RN ( r=0.79, P<0.001) were positive. The mediation analysis showed that the SvO 2 of internal cerebral veins indirectly mediated the relationship between iron content and volume of CN, PUT, GP and THU. Conclusions:The process of iron deposition required the participation of oxygen in deep gray matter nuclei. Volume shows positive correlation with iron content in deep gray matter nuclei, with individual variations. The SvO 2 of internal cerebral veins mediate the relationship between iron content and volume of deep gray matter nuclei.

Objective:To investigate the relationship among iron content, volume and drainage venous oxygen saturation (SvO 2) in deep gray matter nuclei of healthy people using quantitative susceptibility mapping (QSM). Methods:The study was a cross-sectional study. A total of 126 healthy volunteers were prospectively enrolled in the community in Tianjin from June 2019 to December 2023, and 57 males and 69 females, aged 48±15 years. All healthy volunteers underwent MRI examinations to get STrategically Acquired Gradient Echo images, then it was post-processed to obtain T 1 weighted enhanced images, QSM maps and the maximum intensity projection images. In QSM maps, caudate nucleus (CN), putamen (PUT), globus pallidus (GP), thalamus (THU), subthalamic nucleus (STN), substantia nigra (SN) and red nucleus (RN) were semi-automatically segmented to calculate the iron content and volume using SPIN software. Four bilateral deep cerebral veins regions of interest, including septum pellucidum veins, thalamostriate veins, internal cerebral veins and basilar veins, were manually delineated on the maximum intensity projection images of QSM to obtain venous magnetic sensitivity. The venous magnetic sensitivity was calculated as SvO 2. To observe the age-related trend of SvO 2, iron content and volume, the partial correlation analysis was conducted. The relationships between iron content, volume and SvO 2 were explored using the partial correlation analysis. To explore the potential effects of SvO 2 between iron content and volume in deep gray matter, the mediation analysis was utilized. Results:The relationships between the SvO 2 of thalamostriate veins ( r=0.23, P=0.018), basilar veins ( r=0.27, P=0.004) and age were positive. The relationships between the SvO 2 of internal cerebral veins and the iron contents of CN ( r=?0.25, P=0.042) and PUT ( r=?0.33, P<0.001) were negative. The relationships between the SvO 2 of basilar veins and the iron contents of STN ( r=?0.25, P=0.042) and SN ( r=?0.24, P=0.045) were negative. The relationships between iron content and volume including CN ( r=0.46, P<0.001), PUT ( r=0.20, P=0.027), GP ( r=0.76, P<0.001), STN ( r=0.87, P<0.001), SN ( r=0.90, P<0.001), RN ( r=0.79, P<0.001) were positive. The mediation analysis showed that the SvO 2 of internal cerebral veins indirectly mediated the relationship between iron content and volume of CN, PUT, GP and THU. Conclusions:The process of iron deposition required the participation of oxygen in deep gray matter nuclei. Volume shows positive correlation with iron content in deep gray matter nuclei, with individual variations. The SvO 2 of internal cerebral veins mediate the relationship between iron content and volume of deep gray matter nuclei.