集成磁共振成像快速扫描参数对脑组织T1、T2及质子密度测量值的影响

The effect of fast scan parameters on evaluation of T1,T2 relaxation times and proton density of normal brain using synthetic MRI

目的观察多动态多回波(multi-dynamic multi-echo,MDME)序列快速扫描参数对脑组织T1、T2及质子密度(proton density,PD)测量值是否有影响。材料与方法 25例受试者行三组不同扫描参数的MDME序列扫描(EME,NOR,RES)。测量灰质、白质及脑脊液T1、T2及PD值,并比较各组间测量值是否存在差异。将RES组测量值作为参考值,观察EME组、NOR组测量值与参考值之间的相关性。结果脑组织T1、T2及PD测量值在三组之间差异存在统计学意义(P<0.05),T1、T2、PD值最高组间变异系数分别为3.33%、6.48%、5.80%;EME、NOR组测量值与参考值之间有较高相关性(EME:T1:r=0.999,T2:r=0.982,PD:r=0.978;NOR:T1:r=0.999,T2:r=0.985,PD:r=0.986)。结论使用MDME序列快速扫描参数可影响脑组织的定量测量值。临床工作中进行定量评价或随访时要注意扫描参数选择的一致性。

Objective:To investigate the differences of T1,T2 relaxation times,and proton density(PD) measured from multi-dynamic multi-echo(MDME) sequence between fast scan parameters and standard parameters in healthy individuals using 3.0 T scanner,and evaluate the correlations between these quantitative values.Materials and Methods:Twenty-five healthy volunteers were included in the study.Each of them was scanned 3 times using 3 MDME sequences with different scan parameters(group EME,NOR,and RES)respectively.T1,T2 and PD values were simultaneously measured in each of the 28 regions of interest and were compared among different groups with One-way ANOVA.Values of group RES were set as reference values and linear regression was performed for values of group EME and NOR versus the reference values with Pearson correlation.Statistical analysis was performed using SPSS software(23.0.0.0,IBM).Results:Significant differences were displayed when comparing T1,T2,and PD values among 3 groups in the most of brain regions(P<0.05).T1 and PD values have lower discrepancy with the highest intergroup coefficient of variations(CVs) of3.33% and 5.80%,while T2 values has a higher discrepancy with the highest intergroup CV of 6.48%.The linearity in T1,T2,and PD were very strong between group EME and RES(T1,r=0.999;T2,r=0.982;PD,r=0.978) as well as group NOR and RES(T1,r=0.999;T2,r=0.985;PD,r=0.986).Conclusions:Quantitative T1,T2 and PD values acquired from MDME sequence can be affected by fast imaging protocols.The bias of measured T1 and PD values are lower than that of T2 values and the linear correlation between them is positive.It is necessary to set a certain scan parameter for comparing or following up cases quantitatively.