MR体素内不相干运动扩散加权成像预测进展期下咽癌对诱导化疗敏感性价值研究

Pretreatment Intra-Voxel Incoherent Motion Diffusion-Weighted Imaging in Predicting Sensitivity to Induction Chemotherapy Response in Locally Advanced Hypopharyngeal Carcinoma

目的探讨MR体素内不相干运动扩散加权成像（IVIM-DWI）预测进展期下咽癌对诱导化疗敏感性的价值。方法搜集经病理证实的28例下咽癌患者,在治疗前及诱导化疗后3周内分别行IVIM-DWI检查。IVIM序列设置12个b值（0、10、20、30、50、70、100、150、200、400、800和1000 s/mm^2）。分析IVIM双指数模型假性扩散系数（D^＊）、真性扩散系数（D）、灌注分数（f）值,并与单指数模型表观扩散系数（ADC）值进行比较。诱导化疗结束后行疗中评价,根据实体瘤疗效评价标准（RECIST）,将患者分为治疗有效组,包括完全缓解（CR）和部分缓解（PR）;治疗无效组,包括稳定（SD）和进展（PD）。有预测价值的IVIM参数及阈值通过独立样本t检验、单因素方差分析和受试者特征曲线（ROC）分析和确定。结果 28例患者中,18例治疗有效,10例治疗无效。诱导化疗后,IVIM参数中ADC、D值均升高,D^＊值降低（P均〈0.05）,f值改变不明显（P〉0.05）。与治疗无效组比较,治疗有效组的疗前ADC、D值较低,治疗前后ΔADC、ΔD和ΔD^＊较高,而Δf变化不显著。ROC曲线分析疗前D值预测治疗有效最佳,以D值0.847×10^-3mm^2/s为阈值,相应的曲线下面积（AUC）、敏感度和特异度分别为0.806、75.0%和88.9%。结论 IVIM-DWI有助于预测下咽癌对诱导化疗的敏感性。

Objective The aim of this study was to predict sensitivity to induction chemotherapy in patients with locally advanced hypopharyngeal carcinoma by IVIM values. Methods Twenty eight patients with locally advanced hypopharyngeal carcinoma underwent IVIM studies using twelve different b values（b = 0,10,20,30,50,70 100,150,200,400,800 and 1000 s/mm^2）. All patients underwent two MRI studies： a baseline exam before any treatment and a mid-treatment exam 3 weeks after induction chemotherapy. In IVIM approach,D^＊,f and D were extracted from a bi-exponential fit. For comparison,ADC map were extracted from a mono-exponential fit. At the end of induction chemotherapy,patients were classified as responders or non-responders group according to the Response Evaluation Criteria in Solid Tumors criteria（RECIST）,based on their MRI measurement. The predictive value of IVIM parameters were examined with Student＇s t-test,analysis of variance（ANOVA） and receiver operating characteristic（ROC） curves. Results After two cycles of induction chemotherapy,18 patients were categorized into the responder group whereas the other 10 patients were considered nonresponders. Compared with the pretreatment value,the posttreatment ADC value and D value was significantly higher and the posttreatment D value was significantly lower（all P 0. 05）. In contrast,posttreatment f parameter only changed slightly（P 0. 05）. Compared with non-responders,a notably lower pretreatment ADC value,D value,and higher ΔADC,ΔD,and ΔD~＊were observed in responders（all P 0. 05）,but no significant change in Δ f among the two group（P 0. 05）.The ROC curve analysis indicated that the cutoff of pretreatment D value in best predicting tumor ＇s chemotherapeutic response was 0. 847 × 10^-3 mm^2/s,and the corresponding AUC,sensitivity,and specificity were 0. 806,75. 0% and 88. 9%,respectively. Conclusion IVIM-DWI can potentially predict the treatment response to induction chemotherapy for hypopharyngeal carcinoma.