扩散加权成像在鉴别鼻咽癌局部复发和放疗后改变中的应用

The Diffusion Weighted Imaging in Differentiation of Local-recurrence or Postradiation Changes in Nasopharyngeal Carcinoma

[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。

[Purpose] To explore the value of the diffusion weighted imaging（DWI） for differentiation local-recurrence in nasopharyngeal carcinoma（NPC）.[Methods] One-hundred cases of NPC with lesion detected by in conventional MRI postradiotherapy were enrolled.The diffusion weighted imaging and apparent diffusion coefficient（ADC） of lesions were analyzed.[Results] Of 59 cases with local recurrence,3 cases intracranial relapse presented equal signal intensity on the corresponding DWI imaging,and the rest presented high signal intensity.Of 26 cases with edema/ fibrous-inflammatory reaction,2 cases exhibited slightly higher signal intensity on the DWI imaging,the remaining exhibited with low signal intensity.Eight cases with radiation-induced necrosis showed obviously high signal intensity.The mean ADC values of local recurrence,postradiation edema/fibrous-inflammatory reaction and radiation-induced necrosis was 0.84±0.12（×10-3 mm 2 /s）,1.93±0.13（×10-3 mm 2 /s） and 0.41±0.1（×10-3 mm 2 /s）,respectively,with significant difference（F=292.548,P0.01）.When a mean ADC values of less than 1.0×10-3 mm 2 /s and more than 1.5×10-3 mm 2 /s was used as thresholds for differentiating tumor recurrence from treatment-induced changes,the sensitivity of 84.2% and specificity of 71.4%,as well as 86.6% and 100% was obtained respectively.[Conclusion] The appearance of DWI and ADC values of the lesions are useful in differentiating local recurrence from postradiation edema or fibrous-inflammation.