Iron causes proinflammatory activation of microglia near the rim of white matter MS lesion. This is chronic inflammation with associated myelin tissue damage. We propose to use quantitative susceptibility mapping (QSM) to assess chronic inflammation, as hyperintense rim on QSM can be unequivocally interpreted as iron. We use myelin water fraction (MWF) to measure myelin. We have found that MS lesions with hyperintense rims on QSM have lower MWF and higher susceptibility compared to lesions without hyperintense rims on QSM (p<0.01). Hyperintense rim on QSM may provide a biomarker for tissue injury due to iron associated chronic inflammation.