Quantitative susceptibility mapping and R2* are sensitive to myelin and iron changes in multiple sclerosis (MS) lesions. Researchers launched a study to characterize lesion changes on quantitative susceptibility mapping and R2* at various stages. They evaluated 64 patients with MS with different enhancing patterns in white matter lesions: nodular, shell-like, nonenhancing <1 year old, and nonenhancing 1 to 3 years old. They found:

• Of the 203 lesions examined, 80 were nodular-enhancing, of which 77 (96.2%) were isointense on quantitative susceptibility mapping.

• 33 were shell-enhancing, of which 30 (90.9%) were hyperintense on quantitative susceptibility mapping.

• Early active MS lesions with nodular enhancement showed R2* decrease but no quantitative susceptibility mapping change, reflecting myelin breakdown.

• Late active lesions with peripheral enhancement showed R2* decrease and quantitative susceptibility mapping increase in the lesion center, showing further degradation and removal of myelin debris.

• Early or late chronic nonenhancing lesions showed both quantitative susceptibility mapping and R2* increase, reflecting iron accumulation.

Citation: Zhang Y, Gauthier SA, Gupta, A, et al. Quantitative susceptibility mapping and R2* measured changes during white matter lesion development in multiple sclerosis: Myelin breakdown, myelin debris degradation and removal, and iron accumulation. [Published online ahead of print June 2, 2016]. AJNR Am J Neuroradiol. doi:10.3174/ajnr.A4825.