Imaging Center, Harbin Medical University Cancer Hospital, Harbin, P.R. China.
Division of Respiratory Disease, Fourth Hospital of Harbin Medical University, Harbin, 150001, China.
J Magn Reson Imaging. 2019 Jul;50(1):297-304. doi: 10.1002/jmri.26563. Epub 2018 Nov 16.
Non-monoexponential diffusion models are being used increasingly for the characterization and curative effect evaluation of hepatocellular carcinoma (HCC). But the fitting quality of the models and the repeatability of their parameters have not been assessed for HCC.
To evaluate kurtosis, stretched exponential, and statistical models for diffusion-weighted imaging (DWI) of HCC, using b-values up to 2000 s/mm , in terms of fitting quality and repeatability.
Prospective.
Eighteen patients with HCC.
FIELD STRENGTH/SEQUENCE: Conventional and DW images (b = 0, 200, 500, 1000, 1500, 2000 s/mm ) were acquired at 3.0T.
The parameters of the kurtosis, stretched exponential, and statistical models were calculated on regions of interest (ROIs) of each lesion.
The fitting quality was evaluated through comparing the fitting residuals produced on the average data of ROI between different models using a paired t-test or Wilcoxon rank-sum test. Repeatability of the fitted parameters at the median values on the voxelwise data of ROI was assessed using the within coefficient of variation (WCV), the intraclass correlation coefficient (ICC), and the 95% Bland-Altman limits of agreements (BA-LA). The repeatability was divided into four levels: excellent, good, acceptable, and poor, referring to the values of ICC and WCV.
Among three models, the stretched exponential model provided the best fit to HCC (P < 0.05), whereas the statistical model produced the largest fitting residuals (P < 0.05). The repeatability of K from the kurtosis model was excellent (ICC 0.915; WCV 8.79%), while the distributed diffusion coefficient (DDC) from the stretched model was just acceptable (ICC 0.477; WCV 27.83%). The repeatability was good for other diffusion-related parameters.
Considering the model fit and repeatability, the kurtosis and stretched exponential models are the preferred models for the description of the DW signals of HCC with respect to the statistical model.
2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:297-304.
非单指数扩散模型越来越多地用于肝癌（HCC）的特征描述和疗效评估。但是，尚未评估这些模型的拟合质量及其参数的可重复性。
使用高达 2000 s/mm 的 b 值，针对 HCC 的扩散加权成像（DWI），评估峰度、拉伸指数和统计模型的拟合质量和可重复性。
前瞻性。
18 例 HCC 患者。
磁场强度/序列：在 3.0T 上采集常规和 DW 图像（b=0、200、500、1000、1500、2000 s/mm）。
在每个病变的感兴趣区域（ROI）上计算峰度、拉伸指数和统计模型的参数。
通过对不同模型的 ROI 平均数据之间的拟合残差进行配对 t 检验或 Wilcoxon 秩和检验，评估拟合质量。通过 ROI 体素数据的内变异系数（WCV）、组内相关系数（ICC）和 95% Bland-Altman 协议范围（BA-LA）评估拟合参数在中位数时的重复性。根据 ICC 和 WCV 的值，将重复性分为四个等级：优秀、良好、可接受和差。
在这三种模型中，拉伸指数模型最适合 HCC（P<0.05），而统计模型产生的拟合残差最大（P<0.05）。峰度模型的 K 重复性极好（ICC 0.915；WCV 8.79%），而拉伸模型的分布式扩散系数（DDC）仅可接受（ICC 0.477；WCV 27.83%）。其他扩散相关参数的重复性良好。
考虑到模型拟合和可重复性，与统计模型相比，峰度和拉伸指数模型是描述 HCC 的 DW 信号的首选模型。
2 技术功效：2 级 J. Magn. Reson. Imaging 2019；50：297-304.
