磁共振扩散加权成像在鉴别鼻咽癌放疗后鼻咽坏死与复发中的价值

Values of diffusion-weighted imaging in differential diagnosing necrosis and recurrence of nasopharyngeal carcinoma after radiotherapy

目的评价磁共振扩散加权成像(DWI)以及表观扩散系数(ADC)值测量在鼻咽癌放疗后鼻咽坏死与复发鉴别诊断中的应用价值。方法 2008年7月至2010年12月,35例经我院治疗并经病理诊断证实的鼻咽癌放疗后鼻咽坏死和同期随机选取的35例鼻咽癌放疗后复发的患者,均接受了常规MRI检查及DWI(扩散敏感系数,即b值采用:0s/mm2及800s/mm2),分别测量放疗后鼻咽坏死灶及肿瘤复发区的ADC值,计算其平均值。结果鼻咽坏死灶在DWI上表现为不均匀的低信号,而肿瘤复发病灶表现为高信号。鼻咽坏死组及复发组ADC平均值分别为(1.073±0.0383)×10-3mm2/s和(0.844±0.0309)×10-3mm2/s;最大值分别为(1.728±0.0527)×10-3mm2/s和(1.477±0.0675)×10-3mm2/s。鼻咽坏死组ADC平均值及最大值均大于复发组,差异有统计学意义(t1=4.645,P<0.001;t2=2.932,P<0.005)。结论 DWI以及ADC值测量在鼻咽癌放疗后鼻咽坏死与复发的鉴别诊断中具有重要价值,可作为常规MR序列的重要补充。

Objective To evaluate the role of diffusion-weighted imaging （DWI） and the value of apparent diffusion coeffi- cient （ADC） in differential diagnosing necrosis and recurrence of nasopharyngeal carcinoma after radiotherapy. Methods From Jul 2008 to Dec 2010, thirty-five patients were die, gnosed postradiation nasopharyngeal necrosis, which were matched with the same number of patients randomly selected from the same period. All patients were confirmed pathologically, and received rou- tine MRI and DWI （ with the b values of 0s/mm2 and 800s/mm2 ）. ADC values of necrotic loci and parts of recurrence tumor were measured,and their mean ADC values were calculated. Results Nasopharyngeal necrosis usually showed heterogeneity and low signal on DWI, but the recurrence group Showed high signal. The mean ADC values in nasopharyngeal necrosis group and recurrence group were （ 1. 073 ±0. 0383） ×10^-3mm2/s and （0. 844 ±0. 0309） x 10-3mm2/s respectively,the difference of which was statistically significant （t = 4. 645 ,P 〈 0. 001 ）. The maximal values in these two groups were （1. 728 ± 0. 0527） ×10^-3mm2/s and （1. 477 ± 0. 0675） ×10^-3 mm2/s respectively, the difference of which was also statistically significant （t = 2. 932 ,P 〈0. 005）. Conclusions DWI and ADC value are important in differential diagnosis of nasopharyngeal necrosis and tumor recurrence after radiotherapy. DWI and ADC can be used as important supplementary to routine MRI.