中文摘要：

目的：探讨DWI诊断鼻咽癌患者放射治疗后局部复发与纤维化的价值。方法回顾性分析经病理证实为鼻咽癌，行放射治疗后，经穿刺病理或MRI检查随访证实为局部复发的39例患者作为复发组，局部纤维化的51例作为纤维化组进行研究。所有患者均行MR平扫及增强扫描和DWI检查。观察2组患者的DWI表现，测量ADC值并采用独立样本t检验进行比较。采用ROC分析计算常规MRI及DWI诊断鼻咽癌放射治疗后复发的效能，并采用Z检验对曲线下面积进行比较。结果复发组39例患者病灶DWI均表现为高或稍高信号， ADC图上均呈低信号表现。纤维化组51例患者病灶DWI总体信号低于复发组，其中36例病灶ADC图呈等或稍低信号表现，余15例呈稍高信号表现。复发组和纤维化组病灶的ADC值分别为（0.753±0.127）×10-3和（1.233±0.310）×10-3 mm2/s，差异有统计学意义（t＝-9.118，P＜0.05）。 ROC曲线上，确定复发灶的ADC诊断阈值为0.887×10-3 mm2/s， DWI 诊断鼻咽癌复发瘤敏感度为87.18％（34/39），特异度为94.12％（48/51），ROC曲线下面积为0.968。常规MRI诊断复发瘤的敏感度为71.79％（28/39），特异度为74.51％（38/51），ROC曲线下面积为0.732。二者曲线下面积的差异有统计学意义（ Z＝4.583，P＜0.01）。结论 DWI有助于鼻咽癌复发瘤的检出及诊断，且较常规MRI具有更高的诊断效能。

英文摘要：

Objective To investigate the diagnostic value of DWI on nasopharyngeal neoplasm recurrence and fibrotic lesions after radiotherapy.Methods A retrospective analysis of pathologically confirmed nasopharyngeal neoplasm was performed in 39 patients with recurrent patients （ recurrence group ） confirmed by biopsy or MRI follow-up and 51 patients with confirmed localized fibrosis （fibrosis group） after radiotherapy.All patients underwent DWI , non-enhanced and enhanced MR scan.DWI findings and ADC values of the lesions in two groups of patients were observed and measured , then compared by using independent samples t test.Diagnostic performance of routine MRI and DWI in the diagnosis of nasopharyngeal neoplasm recurrence after radiotherapy was calculated by using ROC analysis and the differences of both of them were analyzed by using Z test.Results DWI of 39 recurrent patients showed hyper-intensity signal and ADC map showed hypo-intensity signal appearance.Overall signal of DWI in 51 recurrent patients is lower than that in recurrent group , in which ADC maps of 36 cases showed iso-intensity or moderately hypo-intensity signal appearance and the remaining 15 cases showed moderate hyper-intensity signal appearance.The ADC values of recurrent group and fibrotic group were （0.753 ±0.127） × 10 -3 mm2/s, and （ 1.233 ± 0.310 ） ×10 -3 mm2/s, respectively.The difference was statistically significant （ t=-9.118, P〈0.05）.On the ROC curve, the sensitivity of ADC for the diagnosis of tumor recurrence was 87.18%（34/39）, specificity 94.12%（48/51） and area under the ROC curve 0.968 with the ADC cutoff value of 0.887 ×10 -3 mm2/s.The sensitivity of routine MRI was 71.79% （ 28/39 ） , the specificity 74.51% （ 38/51 ） and the area under the ROC curve was 0.732 for the diagnosis of tumor recurrence.The difference of area under the curve between them was statistically significant （ Z=4.583, P〈0.01）.Conclusion DWI can help tumor detection and diagnosis of recurrent nasopharyngeal neoplasm＆