Abstract： Objective To identify the imaging characteristics of demyelinating plaques in multiple sclerosis (MS) by using susceptibility weighted imaging(SWI),and further explore their morphologic and inicro-hemodynamic evolvements.Methods Thirty-one cases with clinically proven MS received SWI and dynamical susceptibility contrasted MR perfusion imaging(DSC-PI).And 21 cases received MR again in the fbllow-up period,with a time interval of 2.0-20.0 months[mean(7.5±4.8)months].Features of MS plaques in filtered phase images(FPI)were assessed,and the number of MS plaques detected in T1 WI,T2 FLAIR and FPI images were counted respectively.The measurements of phase values and perfusion parameters(including CBF and CBV)were acquired and their variation over time was also evaluated.The number of plaques detected by different MR sequences was compared by using paired t test,and the correlation between phase values and perfusion parameters was evaluated by using Pearson correlative analysis.Results Three types of MS plaques were observed in FPI images,including(1) round or oval hypointense foci without small veins(109 of 298,37%),(2)hypointense foci with small veins(169 of 298, 57% ), (3) abnormal vessels alone without hypointense foci (20 of 298, 7% ). In the 21 cases received MR follow-up, the total and mean plaque numbers identified on T2 FLAIR images were 452 and (22±8) in the first MR examination, and 439 and (21±7)in the second MR examination; and on T1-weithed images, they were 211 and( 10±3 ) in the first MR examination, and 219 and( 10±3 ) in the second MR examination; as well as those on FPI images were 205 and ( 10±3), and 206 and(10±3),respectively. Compared between the first and second MR scan, the mean of number on T2 FLAIR images decreased (t= 2. 28, P= 0. 03 ), and that on FPI images increased( t = -2. 61, P = 0. 02 ), and then that onT1-weight images keep invariable ( t = - 1. 00, P = 0. 33 ). Moreover, a development from regions with "abnormal vessels" alone to hypointense foci were observed in 9 plaques from 6 folh,w-up cases. The changes of phase values of these 9 plaques were significant correlated with CBF' and CBV (r = -0. 73 ,P <0. 05 ;r = -0. 84, P < 0. 05 ). Conclusions Hypointense focus with or without small veins on FPI image is the characteristic manifestation of MS plaques. Combination of SWI and DSC-PI is helpful in further understanding the patho-physiological mechanism of MS plaques and monitoring the evolvement of them.