急性缺血性脑卒中酰胺质子转移成像信号的初步应用

Preliminary application of amide proton transfer imaging signal in acute ischemic stroke

目的 将磁共振（MR）酰胺质子转移（APT）成像技术应用于急性缺血性脑卒中患者,并评价其主要参数在3.5 ppm的磁化转移比率的不对称性[MTRasym（3.5 ppm）]的临床意义.方法 收集2015年3-11月来北京医院急诊入院的急性脑卒中患者参与本项研究,最终有18例患者入组,其中男14例、女4例,平均年龄72岁,年龄范围52 ～92岁,病发时间≤24 h,其中2例≤6 h.所有患者均在3.0TMR下接受颅脑MR扫描.除常规脑卒中扫描协议外,患者加扫APT序列（饱和时间0.8s,饱和强度2 μT）.APT加权（APTW）图通过计算MTRasym（3.5 ppm）形成,直观评价患者APTW,扩散加权成像（DWI）及液体衰减翻转恢复序列（FLAIR）上信号表现.应用Shapiro-Wilk检验样本整体、缺血梗死区以及正常表现白质区（NAWM）的MTRasym（3.5 ppm）值的分布,并使用趋势P-P图对分布的满意度进行评价.使用配对t检验及两样本t检验分别分析患者急性缺血梗死区与其对侧正常表现白质区MTRasym（3.5 ppm）的差异.结果 （1） 18例患者缺血梗死区DWI及FLAIR上均表现为高信号,APT加权图上13例患者梗死区表现为APT效应减低,而5例则表现为等APT效应;NAWM区域,14例为等APT效应,4例APT效应减低.（2）样本整体（W=0.964,P=0.288）、缺血梗死区（W=0.962,P=0.645）及NAWM（W=0.929,P=0.187）的MTRasym（3.5 ppm）值符合正态分布;趋势P-P图所示样本中部分数据的正态偏差值的绝对值＞0.06.（3）患者缺血梗死区的MTRasym（3.5 ppm）（-0.035％±1.020％）显著低于对侧NAWM （0.386％±0.790％）（t=-2.273,P =0.036）;缺血梗死区与NAWM的两样本分组比较中,两者MTRasym（3.5 ppm）差异无统计学意义（t=-1.386,P=0.175）.结论 MTRasym（3.5 ppm）能应用于急性缺血性脑卒中的评价,并具有广阔的临床应用前景.

Objective To apply amide proton transfer magnetic resonance imaging （APT-MRI） technique to acute ischemic stroke,and to discuss clinical values of the APT-MRI main parameter-MTRasym（3.5 ppm）.Methods A total of 18 emergency admitted patients,with acute ischemic stroke from Beijing Hospital,were recruited from March to November 2015.Eventually,18 patients （male 14,female 4,average age 72 years old,age ranged from 52 to 92 years,symptom onset ≤ 24 hours,2 patients ≤ 6 hours） were included in this study.All patients underwent MR scanning on the brain at 3.0 Tesla.Besides the conventional scans for stroke,the APT sequence （saturation time 0.8 s,saturation power 2 μT） was performed.APT weighted （APTW） images were calculated using magnetization transfer ratio asymmetry at 3.5 ppm with respect to water.MRI signals in APTW,diffusion weighted images （DWI） and fluid attenuated iversion recovery （FLAIR） were visually evaluated.Shapiro-Wilk tests were performed to find out the distribution of MTRasym（3.5 ppm） in the whole sample,infarction regions,and normal appearing white matter （NAWMs）,respectively.Detrended normal P-P plots were also used to evaluate its normality.Paired-t test and two-sample t test were applied to compare the mean MTRasym （3.5 ppm） of infarction regions with that of contra lateral NAWMs.Results （1） High signal intensity was observed in DWI and FLAIR in all 18 patients.However,signal intensity was somewhat different in APTW.13 patients were found decreased APT effect,and 5 patients were with equal APT effect in infarction regions.In NAWMs,14 patients were found equal APT effect,and 4 patients were with decreased APT effect.（2） MTRasym （3.5 ppm） s were proven,with Shapiro-Wilk test,to distribute normally within the whole sample （W =0.964,P =0.288）,infarction regions （W =0.962,P =0.645）,and NAWMs（W =0.929,P =0.187）.However,its normality was not so satisfactory due to greater deviations （absolute value 〉 0.06） of some cases in detrended normal P-P plots.（3） Paired-t test analysis showed that MTRasym （3.5 ppm） in infarction regions （-0.035% ± 1.020%） was significantly lower than that in NAWMs （0.386% ± 0.790%） （t =-2.273,P =0.036）.However,there was no statistically significant difference between infarction regions and NAWMs when two sample t-test was performed （t =-1.386,P =0.175）.Conclusion MTRasym （3.5 ppm） can be used to evaluate acute ischemic stroke with a broad future scope in clinical.