PRESS和STEAM波谱在多发性硬化病灶和看似正常表现脑白质区中的价值

Value of point resolved spectrascopy and stimulated echo acquisition mode of ~1H-magnetic resonance in detection of multiple sclerotic foci in brain white matter with normal appearance

目的探讨长回波(echo time,TE)点分辨率波谱(point resolved spectroscopy,PRESS)和激励回波采集模式(stimulated echo acquisition mode,STEAM)2种2-D氢质子磁共振波谱(proton magnetic resonance spectroscopy,1H-MRS)在多发性硬化(multiple sclerosis,MS)病灶及看似正常表现脑白质(normal appearing white matter,NAWM)中的价值。方法对56例复发-缓解型MS(relapsing-remitting MS,RRMS)患者和25例健康志愿者行常规磁共振成像(conventional magneticresonance imaging,cMRI)扫描,并采用PRESSS长回波和STEAM短回波1H-MRS分析,测定各感兴趣区(region of interest,ROI)代谢物氮-乙酰天门冬氨酸(NAA)、胆碱(Cho)、肌酸(Cr)、脂质(Lip)、乳酸(Lac)和肌醇(Ins)的浓度,分析NAA/Cr、Cho/Cr、NAA/Cho、Lac+Lip/Cr和Ins/Cr在病灶和NAWM区中的变化。结果①PRESS长回波显示NAA/Cr、Cho/Cr、NAA/Cho在急性病灶、慢性病灶和对照组相应脑白质(white matter,WM)区三者之间均有显著差异(P<0.01),NAA/Cr、NAA/Cho在急性病灶和慢性病灶间差异不显著(P>0.05);②STEAM短回波显示NAA/Cr、Cho/Cr和Lac+Lip/Cr在急性病灶、NAWM区和对照组相应WM区三者之间均有显著差异(P<0.01);③比较PRESS长回波和STEAM短回波对检测病灶平均代谢物的差异,结果示二者检测NAA/Cr和Cho/Cr无明显差别,但STEAM短回波更能检测到病灶内的Lip、Lac及Ins峰。结论 PRESS长回波和STEAM短回波能检测MS患者脑部病灶及NAWM区的代谢异常,但STEAM短回波较PRESS长回波能探测到更多代谢物。

Objective To study the value of long echo time （TE） point resolved spectroscopy （PRESS） and stimulated echo acquisition mode （STEAM） of 1H-magnetic resonance in detection of multiple scleroses （MS） in brain white matter with a normal appearance.Methods Conventional magnetic resonance imaging was performed in 56 patients with relapsing-remitting MS （RRMS） and in 25 healthy volunteers.The results were analyzed using the long TE PRESS sequence and short TE STEAM sequence of 1H-magnetic resonance.Concentrations of metabolic products,including N-acetylaspartic acid （NAA）,choline （Cho）,creatine （Cr）,lipid （Lip）,lactic acid （Lac）,and inositol （Ins）,were measured in each region of interest （ROI）.Changes of NAA/Cr,Cho/Cr,Lip＋Lac/Cr and Ins/Cr in MS and brain white matter with a normal appearance were analyzed.Results Long TE PRESS sequence showed that the NAA/Cr,Cho/Cr and NAA/Cho were significantly different in white matter with acute and chronic lesions or in white matter with a normal appearance （P0.01）.No significant difference in NAA/Cr and NAA/Cho was observed in white matter with acute and chronic lesions （P0.05）.Short TE STEAM sequence showed that the NAA/Cr,Cho/Cr and Lac＋Lip/Cr were significantly different in white matter with acute lesions or with a normal appearance.Long TE PRESS sequence and short TE STEAM sequence had no significant difference in detecting NAA/Cr and Cho/Cr in MS （P0.05）.However,short TE STEAM sequence was advantageous over long TE PRESS sequence in detecting the Lip,Lac and Ins peaks.Conclusion Both long TE PRESS and short TE STEAM sequence can detect abnormal metabolites in MS and in white matter with a normal appearance.However,STEAM can detect more metabolites than long TE PRESS.