高分辨率磁共振管壁成像最小密度投影技术对大脑中动脉狭窄程度及其伴行微血管及软脑膜动脉评价的可行性研究

Feasibility study of minimum intensity projection of high resolution magnetic resonance vessel wall imaging for evaluating middle cerebral artery stenosis accompanying microvascular and leptomeningeal branches

目的探讨高分辨率磁共振管壁成像(HRMR-VWI)最小密度投影(MinIP)技术评价大脑中动脉(MCA)狭窄程度、狭窄或闭塞MCA周围伴行微血管以及MCA周围软脑膜动脉的可行性。方法本研究从前期急性脑梗死责任斑块(CPAC)相关研究的入组患者中,回顾性连续纳入2014年3月至2017年6月首都医科大学附属北京天坛医院脑血管病中心收治的急性脑梗死患者20例,均为发病6个月内的MCA供血区梗死。所有患者完成头部CT血管成像(CTA)、三维时间飞跃法(3D-TOF)磁共振血管成像(MRA)以及HRMR-VWI。经过原始图像后处理,分别记录CTA、3D-TOF MRA以及HRMR-VWI MinIP对MCA狭窄程度、狭窄或闭塞MCA周围伴行微血管以及MCA周围软脑膜动脉的评估结果。以CTA为标准,采用Kappa分析分别检验3D-TOF MRA和HRMR-VWI MinIP与CTA的一致性。比较3D-TOF MRA与HRMR-VWI MinIP对狭窄或闭塞MCA周围伴行微血管以及MCA周围软脑膜动脉评价的敏感度、特异度、阳性预测值(PPV)、阴性预测值(NPV)的差异。结果(1)20例急性脑梗死患者共40段MCA。对40段MCA狭窄程度进行判读,CTA显示轻中度狭窄26段,重度狭窄12段,闭塞2段;3D-TOF MRA显示轻中度狭窄23段,重度狭窄13段,闭塞4段;HRMR-VWI MinIP显示轻中度狭窄26段,重度狭窄12段,闭塞2段。3D-TOF MRA与CTA评价MCA轻中度狭窄的一致性较好,差异有统计学意义(Kappa=0.843,P<0.01);评价重度狭窄及闭塞的一致性一般,差异有统计学意义(Kappa值分别为0.709、0.643,均P<0.01)。HRMR-VWI MinIP与CTA评价MCA轻中度狭窄、重度狭窄、闭塞的一致性均较好,差异均有统计学意义(Kappa值均为1.000,均P<0.01)。(2)对40段MCA周围伴行微血管进行判读,CTA显示有伴行微血管7段,无伴行微血管33段;3D-TOF MRA显示有伴行微血管2段,无伴行微血管38段;HRMR-VWI MinIP显示有伴行微血管10段,无伴行微血管30段。3D-TOF MRA与CTA对MCA周围伴行微血管判读的一致性较差,差异有统计学意义(Kappa=0.398,P=0.002);HRMR-VWI MinIP与CTA对MCA周围伴行微血管判读的一致性较好,差异有统计学意义(Kappa=0.778,P<0.01)。(3)对40段MCA周围软脑膜动脉进行判读,CTA显示Alberta卒中项目早期CT评分(ASPECTS)M2区、M3区有软脑膜动脉均为39段,无软脑膜动脉均为1段;3D-TOF MRA显示ASPECTS M2区有软脑膜动脉为10段,无软脑膜动脉为30段,ASPECTS M3区有软脑膜动脉为4段,无软脑膜动脉为36段;HRMR-VWI MinIP显示ASPECTS M2区、M3区有软脑膜动脉均为39段,无软脑膜动脉均为1段。3D-TOF MRA与CTA对ASPECTS M2区、M3区软脑膜动脉判读的一致性差异均无统计学意义(均P>0.05);HRMR-VWI MinIP与CTA对ASPECTS M2区、M3区软脑膜动脉判读的一致性均较好,差异均有统计学意义(Kappa值均为1.000,均P<0.01)。(4)HRMR-VWI MinIP诊断MCA周围伴行微血管的敏感度、NPV均高于3D-TOF MRA,差异均有统计学意义(100.0%比28.6%,χ^(2)=7.778,P=0.005;100.0%比86.8%,χ^(2)=4.261,P=0.039);HRMR-VWI MinIP与3D-TOF MRA两种方法特异度和PPV的差异均无统计学意义(均P>0.05)。HRMR-VWI MinIP诊断MCA周围ASPECTS M2区、M3区软脑膜动脉的敏感度、NPV均高于3D-TOF MRA,差异均有统计学意义(M2区:100.0%比25.6%,χ^(2)=46.163,100.0%比3.3%,χ^(2)=14.983;M3区:100.0%比10.3%,χ^(2)=63.488,100.0%比2.8%,χ^(2)=17.986;均P<0.01);HRMR-VWI MinIP与3D-TOF MRA诊断MCA周围ASPECTS M2区、M3区软脑膜动脉的特异度、PPV差异均无统计学意义(均P>0.05)。结论HRMR-VWI MinIP评价MCA狭窄程度、狭窄或闭塞MCA周围伴行微血管以及MCA周围ASPECTS M2~M3区软脑膜动脉与CTA具有较好的一致性,且优于3D-TOF MRA,HRMR-VWI MinIP可能成为评价大脑中动脉狭窄的影像学方法。本研究结果有待进一步验证。

Objective To assess the feasibility of minimum intensity projection(MinIP)of high resolution magnetic resonance vessel wall imaging(HRMR-VWI)for displaying middle cerebral artery(MCA)stenosis,accompanying microvascular adjacent to MCA stenosis or occlusion and MCA leptomeningeal branches.Methods This study included patients from the prior culprit plaque in acute cerebral infarction(CPAC)study.A total of 20 patients,who were admitted to Cerebral Vascular Disease Center of Capital Medical University Affiliated Beijing Tiantan Hospital from March 2014 to June 2017 with recent MCA territory acute ischemic stroke within six months,were consecutively and retrospectively included.All patients completed intracranial computed tomography angiography(CTA),three-dimensional time-of-flight magnetic resonance angiography(3D-TOF MRA)and HRMR-VWI.MCA stenosis,accompanying microvascular and leptomeningeal branches were recorded respectively on CTA,3D-TOF MRA and HRMR-VWI MinIP after postprocessing of the raw images.With CTA as the standard reference,the Kappa values of 3D-TOF MRA and HRMR-VWI MinIP were calculated respectively.The sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV)of 3D-TOF MRA and HRMR-VWI MinIP were calculated and compared.Results(1)There were 40 MCA segments in 20 patients in total.Stenosis of 40 MCA segments were evaluated.On CTA,26 segments showed mild to moderate stenosis,13 showed severe stenosis and 2 showed occlusion.On 3D-TOF MRA,they were 23,13 and 4 respectively,and on HRMR-VWI MinIP,they were 26,12 and 2 respectively.Mild to moderate stenosis was in excellent agreement between 3D-TOF MRA and CTA with statistical difference(Kappa=0.843,P<0.01).Severe stenosis and occlusion were in fair to good agreement with statistical difference(Kappa values were 0.709 and 0.643,respectively;both P<0.01).Mild to moderate stenosis,severe stenosis,and occlusion were showed excellent agreement between HRMR-VWI MinIP and CTA with statistical difference(all Kappa=1.000,all P<0.01).(2)Accompanying microvascular of 40 MCA segments were evaluated.On CTA,it were showed 7 segments with accompanying microvascular and 33 segments without accompanying microvascular.On 3D-TOF MRA,they were 2 and 38 respectively,and on HRMR-VWI MinIP,they were 10 and 30 respectively.Accompanying microvascular was in poor agreement between 3D-TOF MRA and CTA with statistical difference(Kappa=0.398,P=0.002).And accompanying microvascular was in excellent agreement between HRMR-VWI MinIP and CTA with statistical difference(Kappa=0.778,P<0.01).(3)Leptomeningeal branches of 40 MCA segments were evaluated.On CTA,it were showed 39 segments with leptomeningeal branches in both regional M2 and M3 according to Alberta stroke program early CT score(ASPECTS),and only 1 segment without leptomeningeal branches in both regional M2 and M3.On 3D-TOF MRA,10 segments with and 30 segments without leptomeningeal branches in ASPECTS M2;4 segments with and 36 segments without leptomeningeal branches in ASPECTS M3.On HRMR-VWI MinIP,39 segments with and 1 segment without leptomeningeal branches in both ASPECTS M2 and M3.The agreement of leptomeningeal branches between 3D-TOF MRA and CTA in both regional M2 and M3 showed no statistical difference(both P>0.05).Leptomeningeal branches was in excellent agreement between HRMR-VWI MinIP and CTA with statistical difference(both Kappa=1.000,P<0.01).(4)The sensitivity and NPV of accompanying microvascular on HRMR-VWI MinIP were higher than that on 3D-TOF MRA with statistical difference(100%vs.28.6%,χ^(2)=7.778,P=0.005;100.0%vs.86.8%,χ^(2)=4.261,P=0.039).The specificity and PPV of accompanying microvascular between HRMR-VWI MinIP and 3D-TOF MRA showed no statistical difference(both P>0.05).The sensitivity and NPV of leptomeningeal branches in ASPECTS M2 and M3 on HRMR-VWI MinIP were higher than those on 3D-TOF MRA with statistical difference(M2:100.0%vs.25.6%,χ^(2)=46.163,100.0%vs.3.3%,χ^(2)=14.983;M3:100.0%vs.10.3%,χ^(2)=63.488,100.0%vs.2.8%,χ^(2)=17.986;all P<0.01).The specificity and PPV of leptomeningeal branches in ASPECTS M2 and M3 between HRMR-VWI MinIP and 3D-TOF MRA showed no statistical difference(all P>0.05).Conclusions HRMR-VWI MinIP was in excellent agreement with CTA in assessing MCA stenosis,accompanying microvascular adjacent to MCA stenosis or occlusion,and MCA leptomeningeal branches,which outperformed 3D-TOF MRA.HRMR-VWI MinIP has the potential to be used as a imaging method for evaluating MCA stenosis.The results of this study need further verification.