Quantitative susceptibility mapping for iron quantification of deep gray matter in patients with ischemic cerebrovascular events: A systematic review

Quantitative susceptibility mapping (QSM) enables non-invasive assessment of brain iron dysregulation following ischemic injury. We conducted a systematic review to evaluate the role of QSM-derived susceptibility in deep gray matter (DGM) nuclei after ischemic cerebrovascular events (iCVEs). Included studies had to enroll patients with iCVEs who underwent QSM and provide findings of DGM susceptibility. Finally, 11 studies were identified, providing data on hemispheric differences, comparisons with healthy controls, clinical correlates, prognostic value, and longitudinal changes. Meta-analyses were performed on hemispheric differences and demonstrated higher susceptibility in the ipsilateral basal ganglia compared with the contralateral hemisphere. Increased susceptibility was consistently observed in the putamen when compared with healthy controls. Limited cross-sectional evidence suggested positive associations between DGM susceptibility and neurological or functional deficits. Longitudinal findings were scarce and based on small cohorts. However, population homogeneity was evident across studies, mainly due to the predominance of Chinese cohorts, alongside substantial heterogeneity in patient characteristics and methodologies. Overall, current evidence preliminarily suggests increased iron deposition in the basal ganglia after iCVEs, particularly the putamen. Standardized longitudinal studies in geographically diverse populations are needed to strengthen the reliability and cross-study reproducibility of findings and to better clarify their clinical relevance.