Using ‘swallow-tail’ sign and putaminal hypointensity as biomarkers to distinguish multiple system atrophy from idiopathic Parkinson’s disease: A susceptibility-weighted imaging study

Objective To investigate the value of ‘swallow-tail’ sign and putaminal hypointensity on 3 T susceptibility-weighted imaging (SWI) for distinguishing multiple system atrophy (MSA) from idiopathic Parkinson’s disease (IPD). Methods Three groups – 39 MSA patients, 18 IPD patients,and 31 healthy controls (HCs) – were administered a 3 T SWI sequence to evaluate ‘swallow-tail’ sign and putaminal hypointensity using visual scales from 0 to 2 and 0 to 3 scores, respectively. The diagnostic accuracy of the two signs separately and combined was calculated using a receiver operating characteristic curve, with clinical diagnosis as the gold standard. Results The scores of ‘swallow-tail’ sign were lower in IPD than in MSA or in HCs, as well as for putaminal hypointensity in IPD or HCs than in MSA (p