体素内不一致运动磁共振成像后处理中单指数和双指数模型的比较

目的：比较体素内不一致运动磁共振成像（IVIM-MRI）检查后处理中单指数模型和双指数模型测量的一致性。方法：选取行颅脑核磁共振增强扫描确定脑内无病灶的患者30例及转移瘤患者30例进行IVIM和PWI扫描。用双指数模型和单指数模型对不同脑组织部位分别测量慢速扩散ADC（slow ADC）、快速扩散ADC（fast ADC）、快速扩散ADC值分数（Ff）,对两种模型测量值进行比较,并与灌注参数做对比。结果：单指数模型各测量值分别与双指数模型的测量值进行配对t检验,差异均有统计学意义（t=23.268,t=-5.927,t=-17.052;P〈0.05）。Bland-Altman绘图,表明两种模型测量值的一致性好。单指数模型及双指数模型各参数值的总体变异度分别为：slow ADC mono 19%,fast ADC mono 69%,Ff mono 43%;slow ADC Bi 42%,fast ADC Bi171%,Ff Bi 21%。单指数模型fast ADC mono、Ff mono与CBF、CBV呈显著正相关。结论：单指数模型具有更小的变异度,其测量指标fast ADC更能反映组织的灌注情况,更适合临床应用。

Comparison of mono-exponential and bi-exponential model in IVIM post-processing

Objective： To compare the nlono-exponential and bi-exponential model in the determination of diffusion parameters in the post-processing of intravoxel incoherent motion MR imaging （IVIM）. Methods： Thirty patients without brain parenchyma lesions and 50 patients with cerebral metastases underwent IVIM and Perfusion-weighted imaging scanning. The monoexponential model and the bi-exponential model were used to measure the slow ADC, fast ADC and Fraction of Fast ADC for ROls in the brain tissue.Compare with the two models. And contrast this with the infusion. Results： Paired t-test showed statistical significant difference of the measures including slow ADC, fast ADC and Ff between the two models（t=23.268, t=-5.927, t=-17.052; P〈0.05）. The Bland-Altman plots for the measures of mono-exponential model and bi-exponential model indicated good consistency. Measures of the Mono-exponential model had lower overall variability than those of biexponential model （slow ADC 19% VS. 42%, fast ADC 69% VS. 171%, Ff 45% VS. 21%）. Fast ADC and Ff of the Mono-exponential model showed significant relationship with CBF and CBV. Conclusion： There is good consistency of the measures between the mono-exponential and bi-exponential model. Mono-exponential model is superior to the bi-exponential model because of low variability, therefore is more suitable for clinical application.