Multidimensional analysis of cerebral iron and vascular changes in chronic unilateral middle cerebral artery stenosis with quantitative susceptibility mapping, arterial spin labeling and high-resolution vessel wall imaging-a pilot study.

BACKGROUND: A clear understanding of the alterations in iron deposition and their underlying mechanisms in patients with cerebral ischemia remains elusive. This cross-sectional study aimed to multidimensionally analyze cerebral iron deposition variations in patients with chronic unilateral middle cerebral artery (MCA) stenosis using quantitative susceptibility mapping (QSM), arterial spin labeling (ASL), and high-resolution vessel wall imaging (HR-VWI).

METHODS: QSM, ASL, and HR-VWI were performed on 26 patients with unilateral MCA stenosis <70%, 22 patients with stenosis ≥70%, and 24 healthy controls. Seventy-two brain subregions were automatically segmented on QSM and ASL images after registration with HR-VWI images. Susceptibility and cerebral blood flow (CBF) were compared across the three groups, and relationships between stenosis degree, vessel wall enhancement, susceptibility, and CBF were assessed.

RESULTS: Compared to healthy controls or the unaffected sides within the stenosis groups, the affected sides exhibited abnormal iron deposition and alterations in CBF in specific brain regions, particularly those supplied by the MCA. These changes exhibited distinct patterns between the two stenosis groups. Increased susceptibility in key regions was generally associated with decreased CBF (Putamen: Psusceptibility =0.001, PCBF =0.013; globus pallidus: Psusceptibility =0.018, PCBF <0.001; insula: Psusceptibility =0.003, PCBF =0.012; middle frontal gyrus: Psusceptibility =0.041, PCBF =0.042; paracentral lobule: Psusceptibility =0.026, PCBF =0.001; inferior temporal gyrus: Psusceptibility =0.021, PCBF =0.048). Moderate-to-strong positive correlations were found between stenosis degree and susceptibility in regions such as the putamen, globus pallidus, substantia nigra, dentate nucleus, and Heschl's gyrus (correlation coefficients: 0.627, 0.453, 0.345, 0.474, and 0.355, respectively). Additionally, moderate correlations were observed between ipsilateral susceptibility in the putamen, ipsilateral CBF in the globus pallidus, stenosis degree, and vessel wall enhancement (correlation coefficients: 0.302, -0.342, and 0.345, respectively).

CONCLUSIONS: Abnormal iron deposition and CBF alterations in MCA stenosis patients displayed distinct patterns across varying stenosis severity. The observed correlations between stenosis degree, vessel wall enhancement, CBF, and susceptibility demonstrated these factors may contribute to variations in cerebral iron deposition.