基于不同参数估计方法获得的体素内不相干运动量化参数的可重复性研究  

Repeatability study on quantization parameters of intravoxel incoherent motion obtained by different estimation methods

作　　者：张梓雄 杨蔓蔓 张菁菁 乔文俊[1] 熊小丽 ZHANG Zixiong;YANG Manman;ZHANG Jingjing;QIAO Wenjun;XIONG Xiaoli(Medical Imaging Center,Nanfang Hospital,Southern Medical University,Guangzhou 510515,China;Department of Radiology,Hainan Affiliated Hospital of Hainan Medical University,Haikou 570311,China)

机构地区：[1]南方医科大学南方医院医学影像中心,广东广州510515 [2]海南医学院附属海南医院放射科,海南海口570311

出　　处：《中国医学物理学杂志》2023年第10期1251-1254,共4页Chinese Journal of Medical Physics

摘　　要：目的:利用不同参数估计方法,研究磁共振弥散加权成像(DWI)体素内不相干运动参数在正常肾脏皮质中的可重复性。方法:选取18例志愿者使用飞利浦Ingenia 3.0T核磁共振成像设备进行两次自由呼吸腹部肾脏多b值DWI。基于双指数模型,分别用非线性最小二乘拟合方法(NLLS)和贝叶斯估计方法(Bayes)从多b值DWI数据中计算体素不相干运动的量化参数图(D、D*、f)。从左右侧肾脏的皮质分别选取3个大小一致的感兴趣区,分别计算各个参数均值,并通过Bland-Altman评价方法比较两种方法获得的各个参数的可重复性。结果:Bayes方法计算的参数D、f和D*在两次扫描间的变化系数分别为37.4%、30.0%和64.0%,NLLS方法计算获得的参数D、f和D*在两次扫描间的变化系数分别为40.7%、35.2%和53.7%,Bayes方法计算获得的参数值D和f的变化系数低于NLLS方法,前者一致性更好;NLLS方法计算获得的参数值D*的变化系数低于Bayes方法,前者一致性更好。结论:基于双指数模型,可以采用两种方法进行计算,Bayes方法计算获取D和f值,NLLS方法计算获取D*值,以提升肾脏皮质各个定量参数的稳定性和可靠性。Objective To study the repeatability of intravoxel incoherent motion(IVIM)parameters of diffusion weighted imaging(DWI)in normal renal cortex obtained by two different estimation methods.Methods Eighteen volunteers were enrolled and underwent free-breathing abdominal-renal multi-b-value DWI twice using Philips Ingenia 3.0T magnetic resonance imaging equipment.Based on the double exponential model,the quantization parameter maps(D,D*,f)of IVIM were calculated from multi-b-value DWI data using non-linear least squares(NLLS)method and Bayesian estimation(Bayes)method.Three equally sized regions of interest were selected from bilateral renal cortex,and the mean of each parameter was calculated.Th repeatability of each parameter estimated by the two methods was analyzed using Bland-Altman method.Results The coefficients of variation of parameters D,f,and D*calculated by Bayes method between two scans were 37.4%,30.0%,and 64.0%,respectively;while those calculated by NLLS method between two scans were 40.7%,35.2%,and 53.7%,respectively.The coefficients of variation of parameters D and f calculated by Bayes method were lower than those of NLLS method,indicating that Bayes method had better consistency;and the coefficient of variation of D*obtained by NLLS method was lower than that of Bayes method,indicating that NLLS method had better consistency.Conclusion The stability and reliability of various quantitative parameters in the renal cortex can be improved by two methods based on double exponential model:using Bayes method to obtain parameters D and f,and using NLLS method to obtain parameter D*.

关 键 词：肾脏皮质 弥散加权成像 不相干运动 双指数模型 

分 类 号：R318[医药卫生—生物医学工程] R811[医药卫生—基础医学]