Department of Radiology, Northern Jiangsu People's Hospital, Clinical Medical School of Yangzhou University, No. 98 Nantong West Road, Yangzhou, 225001, People's Republic of China.
Department of Radiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, 107 Yan Jiang West Road, Guangzhou, 510120, People's Republic of China.
Eur Radiol. 2020 Nov;30(11):6022-6032. doi: 10.1007/s00330-020-07005-2. Epub 2020 Jun 26.
To compare diffusion parameters obtained from mono-exponential, bi-exponential, and stretched-exponential diffusion-weighted imaging (DWI) in stratifying non-alcoholic fatty liver disease (NAFLD).
Thirty-two New Zealand rabbits were fed a high-fat/cholesterol or standard diet to obtain different stages of NAFLD before 12 b-values (0-800 s/mm) DWI. The apparent diffusion coefficient (ADC) from the mono-exponential model; pure water diffusion (D), pseudo-diffusion (D*), and perfusion fraction (f) from bi-exponential DWI; and distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) from stretched-exponential DWI were calculated for hepatic parenchyma. The goodness of fit of the three models was compared. NAFLD severity was pathologically graded as normal, simple steatosis, borderline, and non-alcoholic steatohepatitis (NASH). Spearman rank correlation analysis and receiver operating characteristic curves were used to assess NAFLD severity.
Upon comparison, the goodness of fit chi-square from stretched-exponential fitting (0.077 ± 0.012) was significantly lower than that for the bi-exponential (0.110 ± 0.090) and mono-exponential (0.181 ± 0.131) models (p < 0.05). Seven normal, 8 simple steatosis, 6 borderline, and 11 NASH livers were pathologically confirmed from 32 rabbits. Both α and D increased with increasing NAFLD severity (r = 0.811 and 0.373, respectively; p < 0.05). ADC, f, and DDC decreased as NAFLD severity increased (r = - 0.529, - 0.717, and - 0.541, respectively; p < 0.05). Both α (area under the curve [AUC] = 0.952) and f (AUC = 0.931) had significantly greater AUCs than ADC (AUC = 0.727) in the differentiation of NASH from borderline or less severe groups (p < 0.05).
Stretched-exponential DWI with higher fitting efficiency performed, as well as bi-exponential DWI, better than mono-exponential DWI in the stratification of NAFLD severity.
• Stretched-exponential diffusion model fitting was more reliable than the bi-exponential and mono-exponential diffusion models (p = 0.039 and p < 0.001, respectively). • As NAFLD severity increased, the diffusion heterogeneity index (α) increased, while the perfusion fraction (f) decreased (r = 0.811, - 0.717, p < 0.05). • Both α and f showed superior NASH diagnostic performance (AUC = 0.952, 0.931) compared with ADC (AUC = 0.727, p < 0.05).
比较单指数、双指数和拉伸指数扩散加权成像（DWI）在非酒精性脂肪性肝病（NAFLD）分层中的扩散参数。
32 只新西兰兔分别给予高脂/胆固醇饮食或标准饮食，以在 12 个 b 值（0-800 s/mm）DWI 前获得不同阶段的 NAFLD。从单指数模型中计算表观扩散系数（ADC）；从双指数 DWI 中计算纯水扩散（D）、伪扩散（D*）和灌注分数（f）；从拉伸指数 DWI 中计算分布扩散系数（DDC）和水分子扩散异质性指数（α）。比较三种模型的拟合优度。NAFLD 严重程度通过病理学分级为正常、单纯性脂肪变性、边界性和非酒精性脂肪性肝炎（NASH）。采用 Spearman 秩相关分析和受试者工作特征曲线评估 NAFLD 严重程度。
与双指数（0.110±0.090）和单指数（0.181±0.131）模型相比，拉伸指数拟合的卡方拟合优度（0.077±0.012）显著降低（p<0.05）。32 只兔子中，7 只正常、8 只单纯性脂肪变性、6 只边界性和 11 只 NASH 肝脏通过病理学证实。随着 NAFLD 严重程度的增加，α 和 D 均增加（r=0.811 和 0.373，p<0.05）。ADC、f 和 DDC 随着 NAFLD 严重程度的增加而降低（r=-0.529、-0.717 和-0.541，p<0.05）。α（曲线下面积[AUC]=0.952）和 f（AUC=0.931）的 AUC 明显大于 ADC（AUC=0.727），用于区分 NASH 与边界性或更严重的组（p<0.05）。
在 NAFLD 严重程度分层中，与双指数 DWI 相比，拉伸指数 DWI 具有更高的拟合效率，与单指数 DWI 相比表现更好。
拉伸指数扩散模型拟合比双指数和单指数扩散模型更可靠（p=0.039 和 p<0.001）。
随着 NAFLD 严重程度的增加，扩散异质性指数（α）增加，而灌注分数（f）降低（r=0.811，-0.717，p<0.05）。
α 和 f 与 ADC（AUC=0.727，p<0.05）相比，具有更好的 NASH 诊断性能（AUC=0.952，0.931）。
