Objective:To investigate the brain iron status in the sensorimotor cortex of patients with chronic low back pain (CLBP) and its relationship with changes in resting-state functional connectivity (RS-FC).Methods:This was a cross-sectional study. Thirty-two patients with CLBP (CLBP group) who were treated at Wuxi People′s Hospital Affiliated to Nanjing Medical University from July 2023 to March 2024 and 30 age-and gender-matched healthy volunteers (control group) were prospectively included. All subjects underwent pain and neuropsychological assessments and head MRI examinations, including conventional sequences, quantitative susceptibility mapping (QSM), and blood oxygen level-dependent (BOLD) functional MRI. QSM values of the sensorimotor cortex and the left middle frontal gyrus, right inferior temporal gyrus, right olfactory cortex, and right posterior cingulate gyrus were extracted using the ANTs toolkit. The bilateral postcentral gyrus and posterior portion of the bilateral precentral gyrus in the sensorimotor cortex were selected as seed points using SPM software to extract the average time series of BOLD signals and evaluate the changes in RS-FC values with other brain regions. Two-sample t-tests were used to compare the differences in QSM values and RS-FC values between the two groups. Pearson correlation analysis was used to analyze the correlation between iron deposition in key brain regions and RS-FC values and clinical scale scores. Results:The QSM values in the posterior portion of the bilateral precentral gyrus and the left postcentral gyrus in the CLBP group were significantly higher than those in the control group ( t=2.17, P=0.009; t=4.44, P<0.001), and the QSM value in the left postcentral gyrus was positively correlated with pain-related scale scores ( P<0.05). Compared with the control group, the QSM values in the left orbital part of the middle frontal gyrus ( t=2.22, P=0.031) and the right inferior temporal gyrus ( t=2.98, P=0.004) were increased, while the QSM values in the right olfactory cortex ( t=2.54, P=0.014) and the right posterior cingulate gyrus ( t=2.70, P=0.009) were decreased in the CLBP group. Compared with the control group, the RS-FC values between the left postcentral gyrus, the posterior part of the bilateral precentral gyrus, and the left superior frontal gyrus were increased in the CLBP group ( P<0.001), the RS-FC value between the right postcentral gyrus and the right precuneus was increased ( P<0.001). The RS-FC of the bilateral motor cortex and the left dorsolateral superior frontal gyrus was positively correlated with the QSM values of the bilateral motor cortex ( r=0.444, P=0.015). Conclusion:Iron deposition in the sensorimotor cortex (posterior portion of the bilateral precentral gyrus and the left postcentral gyrus) is increased in CLBP patients and is correlated with abnormal functional connectivity within and between brain regions.

Objective:To investigate the brain iron status in the sensorimotor cortex of patients with chronic low back pain (CLBP) and its relationship with changes in resting-state functional connectivity (RS-FC).Methods:This was a cross-sectional study. Thirty-two patients with CLBP (CLBP group) who were treated at Wuxi People′s Hospital Affiliated to Nanjing Medical University from July 2023 to March 2024 and 30 age-and gender-matched healthy volunteers (control group) were prospectively included. All subjects underwent pain and neuropsychological assessments and head MRI examinations, including conventional sequences, quantitative susceptibility mapping (QSM), and blood oxygen level-dependent (BOLD) functional MRI. QSM values of the sensorimotor cortex and the left middle frontal gyrus, right inferior temporal gyrus, right olfactory cortex, and right posterior cingulate gyrus were extracted using the ANTs toolkit. The bilateral postcentral gyrus and posterior portion of the bilateral precentral gyrus in the sensorimotor cortex were selected as seed points using SPM software to extract the average time series of BOLD signals and evaluate the changes in RS-FC values with other brain regions. Two-sample t-tests were used to compare the differences in QSM values and RS-FC values between the two groups. Pearson correlation analysis was used to analyze the correlation between iron deposition in key brain regions and RS-FC values and clinical scale scores. Results:The QSM values in the posterior portion of the bilateral precentral gyrus and the left postcentral gyrus in the CLBP group were significantly higher than those in the control group ( t=2.17, P=0.009; t=4.44, P<0.001), and the QSM value in the left postcentral gyrus was positively correlated with pain-related scale scores ( P<0.05). Compared with the control group, the QSM values in the left orbital part of the middle frontal gyrus ( t=2.22, P=0.031) and the right inferior temporal gyrus ( t=2.98, P=0.004) were increased, while the QSM values in the right olfactory cortex ( t=2.54, P=0.014) and the right posterior cingulate gyrus ( t=2.70, P=0.009) were decreased in the CLBP group. Compared with the control group, the RS-FC values between the left postcentral gyrus, the posterior part of the bilateral precentral gyrus, and the left superior frontal gyrus were increased in the CLBP group ( P<0.001), the RS-FC value between the right postcentral gyrus and the right precuneus was increased ( P<0.001). The RS-FC of the bilateral motor cortex and the left dorsolateral superior frontal gyrus was positively correlated with the QSM values of the bilateral motor cortex ( r=0.444, P=0.015). Conclusion:Iron deposition in the sensorimotor cortex (posterior portion of the bilateral precentral gyrus and the left postcentral gyrus) is increased in CLBP patients and is correlated with abnormal functional connectivity within and between brain regions.