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[目的]探讨扩散加权成像(DWI)在鉴别鼻咽癌局部复发与放疗后改变中的价值。[方法]放射治疗后常规MRI发现异常病变的100例NPC入组,分析DWI表现,测量病变处的表观扩散系数(ADC),并对不同性质病变的ADC值进行比较。[结果]59例局部复发,3例颅内复发灶DWI图像呈等信号,余均呈高信号。26例放疗后水肿/纤维炎症反应2例DWI呈稍高信号,余均呈低信号。8例放射性坏死DWI均呈明显高信号。局部复发、放疗后水肿/纤维炎症反应及放射性坏死的平均ADC值分别为0.84±0.12(×10-3mm2/s)、1.93±0.13(×10-3mm2/s)及0.41±0.10(×10-3mm2/s),三组ADC值有显著性差异(F=292.548,P<0.01)。以平均ADC值<1.0×10-3mm2/s及>1.5×10-3mm2/s,分别作为诊断局部复发和放疗后水肿/炎症反应的阈值,敏感度、特异性分别为84.2%、71.4%及86.6%、100%。[结论]DWI表现及病变的ADC值差异有助于鼻咽癌局部复发与放疗后水肿/纤维炎症反应等的鉴别诊断。
[Objective] To investigate the value of diffusion-weighted imaging (DWI) in differentiating nasopharyngeal carcinoma from local recurrence and radiotherapy. [Methods] A total of 100 NPC patients with abnormal lesions in conventional MRI after radiotherapy were enrolled in the study. The DWI was analyzed and the apparent diffusion coefficient (ADC) was measured. The ADC values of the lesions were compared. [Results] In 59 cases of local recurrence, 3 cases of intracranial reoccurrence DWI images showed equal signal, all showed high signal. 26 cases of post-radiotherapy edema / fibrous inflammatory response in 2 cases showed DWI slightly higher signal, the remaining were low signal. 8 cases of radioactive necrosis DWI were significantly higher signal. The average ADC values of local recurrence, post-radiotherapy edema / fibroinflammation and radioactive necrosis were 0.84 ± 0.12 (× 10-3mm2 / s), 1.93 ± 0.13 (× 10-3mm2 / s) and 0.41 ± 0.10 3mm2 / s), three groups of ADC values were significantly different (F = 292.548, P <0.01). The average ADC values <1.0 × 10-3mm2 / s and> 1.5 × 10-3mm2 / s were the thresholds for the diagnosis of edema / inflammation after local recurrence and radiotherapy. The sensitivity and specificity were 84.2%, 71.4% and 86.6%, 100%. [Conclusion] The differences of ADC value between DWI manifestations and lesions are helpful for the differential diagnosis of local recurrence of nasopharyngeal carcinoma and edema / fibroinflammation after radiotherapy.