Subdivisional Iron Deposition and “Swallow Tail Sign” of Substantia Nigra in RRMS Patients by Quantitative Susceptibility Mapping

Motivation: Regionally progressive iron deposition has not been indicated in the substantia nigra (SN), which is the main impaired region in relapsing-remitting multiple sclerosis (RRMS). Goal(s): To study the iron accumulation in substantia nigra (SN) subdivisions and “swallow tail sign” in RRMS patients with different DDs. Approach: Quantitative susceptibility mapping (QSM) values were measured in the anterior and posterior SN at different levels. Results: QSM values of the SN were higher in RRMS patients with 5-10 years DDs than controls. There were significantly positive correlations between “swallow tail sign” scores and QSM values of the caudal pSN in the patients with long DDs. Impact: This is a preliminary study providing objective evidence of the iron-related progression of SN subregions in RRMS patients with different DDs, and abnormal “swallow tail sign” may provide an additional imaging maker for MS patients.