低浓度对比剂CE-MRA在急性缺血性脑卒中磁共振血管成像及灌注成像中的应用价值

Application value of low concentration contrast agent CE-MRA in MR angiography and perfusion imaging of acute ischemic stroke

目的探讨低浓度对比剂在急性缺血性脑卒中MRA及灌注成像(PWI)中的应用价值。方法前瞻性纳入临床怀疑卒中且需做MRA及PWI的患者40例,随机分为常规浓度组(20例,对比剂浓度0.5 mmol/ml)和低浓度组(20例,对比剂浓度0.25 mmol/ml)。比较两组患者的图像质量评分、信号差异及缺血半暗带情况,并以DSA为金标准,分别比较两组患者动脉狭窄程度。结果低浓度组与常规浓度组间图像质量评分的差异无统计学意义[(3.75±0.64)vs.(3.85±0.67);t=-0.483,P=0.632]。低浓度组颈总动脉分叉处信号强度(SI)(1198.30±43.52)低于常规浓度组(1222.95±54.47),信噪比(SNR)(201.85±28.71)、对比噪声比(CNR)(197.95±24.53)稍高于低浓度组[(191.15±16.58),(180.80±22.48)],两组间差异无统计学意义(均P>0.05)。低浓度组大脑中动脉起始处SI(1535.70±69.97)、SNR(230.25±16.86)、CNR(211.05±21.13)均低于常规浓度组[(1543.61±93.38),(307.85±15.82),(279.10±14.94)],两组间SI差异无统计学意义(P>0.05),而两组间SNR、CNR的差异均有统计学意义(均P<0.05)。常规浓度组CE-MRA诊断动脉狭窄的准确率为94.92%,低浓度组CE-MRA诊断动脉狭窄的准确率为94.34%。两组DSC-PWI诊断缺血半暗带观察者间一致性均较好(k=0.87;k=0.86)。结论低浓度对比剂CE-MRA和PWI扫描在不影响图像诊断质量的前提下,可降低对比剂注入量、减少对患者的损害,是一种可行的急性脑卒中的MRI扫描方案。

Objective To explore the application value of low concentration contrast agent in MRA and perfusion imaging(PWI)of acute ischemic stroke.Methods Forty patients with clinical suspected stroke and needed MRA and PWI were randomly divided into conventional dose group(20 cases,contrast agent concentration 0.5 mmol/ml)and low dose group(20 cases,contrast agent concentration 0.25 mmol/mLl).The image quality score,signal difference and ischemic penumbra of two groups were compared,and arterial stenosis degree of two groups was compared by DSA as the gold standard.Results There was no significant difference in image quality score between the low dose group and conventional dose group[(3.75±0.64)vs.(3.85±0.67);t=-0.483,P=0.632].The signal intensity(SI)of the common carotid artery in the low dose group(1198.30±43.52)were lower than that in conventional dose group(1222.95±54.47),while signal-to-noise ratio(SNR)(201.85±28.71)and contrast-to-noise ratio(CNR)(197.95±24.53)were slight higher than those in conventional dose group[(191.15±16.58),(180.80±22.48)],and there was no significant difference between the two groups(all P>0.05).The SI(1535.70±69.97),SNR(230.25±16.86),CNR(211.05±21.13)of middle cerebral artery in the low dose group were also lower than those in the conventional dose group[(1543.61±93.38),(307.85±15.82),(279.10±14.94)],the SI had no statistical difference(P>0.05)while the SNR and CNR had significant difference between the two groups(all P<0.05).The accuracy of CE-MRA in diagnosing arterial stenosis was 94.92%in conventional dose group and 94.34%in low dose group.The inter-observer agreements in the diagnosis of ischemic penumbra with DSC-PWI were both excellent in two groups(k=0.87;k=0.86).Conclusion Low concentration contrast agent CE-MRA and PWI scanning can reduce contrast agent injection and damage to patients without affecting the image diagnosis quality,it is a feasible MRI scanning scheme for acute stroke.