Lai Vincent, Lee Victor Ho Fun, Lam Ka On, Sze Henry Chun Kin, Chan Queenie, Khong Pek Lan
Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, Queen Mary Hospital, University of Hong Kong, Room 406, Block K, Pok Fu Lam, Hong Kong,
Eur Radiol. 2015 Jun;25(6):1708-13. doi: 10.1007/s00330-014-3535-9. Epub 2014 Dec 23.
To determine the utility of stretched exponential diffusion model in characterisation of the water diffusion heterogeneity in different tumour stages of nasopharyngeal carcinoma (NPC).
Fifty patients with newly diagnosed NPC were prospectively recruited. Diffusion-weighted MR imaging was performed using five b values (0-2,500 s/mm(2)). Respective stretched exponential parameters (DDC, distributed diffusion coefficient; and alpha (α), water heterogeneity) were calculated. Patients were stratified into low and high tumour stage groups based on the American Joint Committee on Cancer (AJCC) staging for determination of the predictive powers of DDC and α using t test and ROC curve analyses.
The mean ± standard deviation values were DDC = 0.692 ± 0.199 (×10(-3) mm(2)/s) for low stage group vs 0.794 ± 0.253 (×10(-3) mm(2)/s) for high stage group; α = 0.792 ± 0.145 for low stage group vs 0.698 ± 0.155 for high stage group. α was significantly lower in the high stage group while DDC was negatively correlated. DDC and α were both reliable independent predictors (p < 0.001), with α being more powerful. Optimal cut-off values were (sensitivity, specificity, positive likelihood ratio, negative likelihood ratio) DDC = 0.692 × 10(-3) mm(2)/s (94.4 %, 64.3 %, 2.64, 0.09), α = 0.720 (72.2 %, 100 %, -, 0.28).
The heterogeneity index α is robust and can potentially help in staging and grading prediction in NPC.
• Stretched exponential diffusion models can help in tissue characterisation in nasopharyngeal carcinoma • α and distributed diffusion coefficient (DDC) are negatively correlated • α is a robust heterogeneity index marker • α can potentially help in staging and grading prediction.
确定拉伸指数扩散模型在鼻咽癌（NPC）不同肿瘤分期中水扩散异质性特征描述中的效用。
前瞻性招募50例新诊断的NPC患者。使用五个b值（0 - 2500 s/mm²）进行扩散加权磁共振成像。计算各自的拉伸指数参数（DDC，分布扩散系数；以及α，水异质性）。根据美国癌症联合委员会（AJCC）分期将患者分为低肿瘤分期组和高肿瘤分期组，使用t检验和ROC曲线分析来确定DDC和α的预测能力。
低分期组的平均±标准差数值为DDC = 0.692 ± 0.199（×10⁻³ mm²/s），高分期组为0.794 ± 0.253（×10⁻³ mm²/s）；低分期组的α = 0.792 ± 0.145，高分期组为0.698 ± 0.155。高分期组的α显著更低，而DDC呈负相关。DDC和α都是可靠的独立预测指标（p < 0.001），α的预测能力更强。最佳截断值为（灵敏度、特异度、阳性似然比、阴性似然比）DDC = 0.692×10⁻³ mm²/s（94.4%，64.3%，2.64，0.09），α = 0.720（72.2%，100%， - ，0.28）。
异质性指数α具有稳健性，可能有助于NPC的分期和分级预测。
• 拉伸指数扩散模型有助于鼻咽癌的组织特征描述 • α与分布扩散系数（DDC）呈负相关 • α是一个稳健的异质性指数标志物 • α可能有助于分期和分级预测
