肝脏多b值弥散加权成像的信号衰减模型研究  

Study of the signal decay model based on multi-b-value diffusion-weighted imaging in liver

作　　者：朱柳红[1] 罗文斌[1] 成启华[1] 郭岗[1] 

机构地区：[1]厦门市第二医院医学影像科,361021

出　　处：《功能与分子医学影像学（电子版）》2014年第2期5-10,共6页Functional and Molecular Medical Imaging(Electronic Edition)

基　　金：福建省科技计划重点项目(2010D027);福建省卫生厅青年课题(2012-2-88)

摘　　要：目的从数学拟合的角度探讨磁共振弥散加权成像技术的信号模型并进行对比研究及评价。方法对12名健康志愿者进行肝脏磁共振弥散加权成像(b值取10个,分别为:10、20、30、50、100、200、300、500、800、1200 s/mm2)扫描,测量肝脏S7段的感兴趣区信号值。利用单幂数与双幂数模型分别对采集到的正常肝实质信号进行曲线拟合,对比单幂数获取的表观弥散系数(ADC)值及利用双幂数模型获取的弥散成分、灌注成分及灌注系数,分析二者拟合的优劣。结果单幂数及双幂数模型的主要拟合参数残差平方和SSE分别为(13.53±8.89)×10-3,(5.70±3.90)×10-3;确定系数R2分别为(973.19±13.20)×10-3,(988.30±6.02)×10-3。经独立样本t检验分析,两组的SSE及R2值的差异均有统计学意义(P值分别为0.011及0.003,P<0.05)。利用单幂数获取的ADC值为(1.57±0.19)×10-3;利用双幂数模型获取的弥散值D、灌注值D*及灌注分数f平均值分别为(1.34±0.25)×10-3,(31.96±7.51)×10-3及(22.49±4.16)﹪。结论双幂数模型拟合参数均优于单幂数模型,双幂数模型更适合于DWI信号的合理描述,且本研究的数学拟合方法可获取纯弥散值D、灌注值D*及灌注分数f值,做到弥散与灌注分离开,并为下一步分析肝脏占位性病变的弥散及灌注成分提供基础。Objective To compare effectiveness of the curve fitting between the mono-exponential and bi-exponential model in describing the signal change in the liver diffusion-weighted imaging（DWI）. Methods Twelve healthy volunteers were scanned with liver diffusion-weighted imaging with 10 diffusion-sensitive values（b-values = 10, 20, 30, 50, 100, 200, 300, 500, 800, 1200 s/mm2）. The measured DWI signals（S7 of liver） were fitted with mono-exponential and bi-exponential model respectively. The results was analyzed between two models. Results The SSE mean values of mono-exponential model and bi-exponential model are（13.53 ± 8.89） × 10^-3 and（5.70 ± 3.90） ×10^-3 respectively, while the R2 values are（973.19 ± 13.20） ×10^-3 and（988.30 ± 6.02） × 10^-3 respectively. There is a significant difference in SSE value and R2 value between two models under t-test analysis（P = 0.011 and 0.003, respectively）. The mean ADC value by mono-exponential model is（1.57 ± 0.19） × 10^-3. While pure diffusion value D, perfusion value D＊ and perfusion fraction value fby bi-exponential model, are（1.34 ± 0.25） × 10^-3,（31.96 ± 7.51） × 10^-3 and（22.49 ± 4.16） ﹪ respectively. Conclusion Signal in liver DWI fitted better with bi-exponential model than with the mono-exponential model, which demonstrates that the former is much more suitable in describing the DWI signal than the latter. Furthermore, we can obtain D, D＊ and f values by the mathematical fitting method in this paper, which provides a basis for the further research on diffusion and perfusion analysis of liver lesions.

关 键 词：磁共振 信号衰减模型 评估参数 多b值技术 

分 类 号：R445.2[医药卫生—影像医学与核医学] R323.1[医药卫生—诊断学]