The Application Of 3.0 T Hrmri In Middle Cerebral Artery Atherosclerotic Stenosis

ObjectiveTo explore the value of the application of HRMRI in middle cerebral artery athero-sclerotic stenosis.Materials and methods61 patients with unilateral MCA M1 segment stenosis were diagnosed by the 3D-TOF MRA or the clinical diagnosis and 15 healthy volunteers.8 patients were excluded from analysis:the patients with contraindications to MRI;co-existent ipsilateral intracranial or extracranial internal carotid artery stenosis or occlusion?stenosis rate?50%?;non-athero-sclerotic vascular abnormalities;co-existent other intracranial non-vascular lesions;the patients can not be cooperated with checking or the images are not suitable for data measurement and analysis.MRI was performed with a 3.0 T superconductive MRI scanner?Magnetom Skyra,Siemens,Germany?and a 20-channel head phased array coil.All patients initially underwent regular brain scanning,3D-TOF MRA and then HRMRI scanning.The patients then underwent the sequence of HRMRI T₁WI scanning after they were injected with Gd-DTPA.All images were transferred to a workstation?Syngo.via,Siemens,Germany?.The distribution and the signal characteristics of the plaque were determined.The plaques were classified.The thickness of plaque,the luminal diameter and the outer area of the narrow,and the reference point were measured.The degree of stenosis and remodeling index were calculated then.A two-sided?level of 0.05 was used to infer the statistically significant difference.All statistical analyses were performed using SPSS20.0.Statistical significant was defined as a P-value less than 0.05.ResultThis study inincluded 53 patients in which symptomatic group of middle cerebral artery stenosis contained 36 cases and asymptomatic group of middle cerebral artery stenosis contained 17 cases,and 15 healthy volunteers.All the patients,plaques were more frequently located at the ventral?39.62%?and the inferior?35.85%?wall of the most narrow cross section of the blood vessels,comparing with the plaques located at the superior?13.21%?and posterior?11.32%?wall.The thickness of plaque mainly distributed between 0.5 and 2.5 mm,and which between 1.0 and 1.5 mm?excluding 1.0 mm?accounted for about 50.94%.With the thickness of plaque increases,the number of plaques gradually reduces.The degree of stenosis in symptomatic group was 0.50±0.27 as com-pared with asymptomatic group?0.46±0.22;t=0.532,P?0.05?.The remodeling ratio in symptomatic group was 1.14±0.18 as compared with asymptomatic group?0.91±0.17;t=4.418,P?0.05?.We got 180 positive vascular sections that conform to the requirements,54?30.00%?were type?plaques,then followed by type?-???a?plaques 56?31.11%?,type?plaques 49?27.22%?,and type???c?plaques 21?11.67%?.The soft plaques?type?-???a?,type??were 105?58.33%?as compared with 75?41.67%?the hard plaques?type?,type???c??.There was no statistical significant between the two kinds of plaques in the distribution of bilateral MCA M1 segments??2=0.827,P?0.05?.Conclusion1?Not only can HRMRI display the vascular lumen,but it displays the vascular wall clearly.2?Middle cerebral artery atherosclerotic plaques are more frequently located at the ventral and inferior wall,the opposite to the orifices of penetrating arterial branches.With the thickness of plaques increases,when it increases to a certain degree,the number of plaques decreases due to its own tension easy to make plaque rupture.3?HRMRI can determine the stenosis degree of MCA,and it also can evaluate the vascular remodeling model.The symptomatic group and asymptomatic group are charac-terized by expansive remodeling and constrictive remodeling,respectively.4?HRMRI can be used to display the atherosclerotic plaques.It can classify them by AHA sub-type and initially evaluate their stability.