扩散加权成像鉴别诊断鼻咽癌和鼻咽部淋巴瘤

Diffusion-weighted imaging in differentiating nasopharyngeal carcinoma and nasopharyngeal lymphoma

目的探讨DWI鉴别诊断鼻咽癌(NPC)及鼻咽部淋巴瘤(NPL)的价值。方法回顾性分析经病理证实的22例NPC和27例NPL的平扫、增强MRI及DWI图像,对比分析两者的平均ADC值和病灶与未受侵翼外肌ADC值的比值(rADC值),应用ROC曲线分析以ADC值、rADC值鉴别诊断NPC与NPL的效能。结果 NPC与NPL均于T1WI呈等或稍低信号、T2WI呈稍高信号。NPC于DWI(b=1000s/mm2)上呈稍高信号、ADC图上呈等低信号,NPL于DWI(b=1000s/mm2)上呈高信号、ADC图上呈低信号。NPC组ADC值为(842.34±94.66)×10-6 mm2/s、rADC值为0.74±0.08。NPL组ADC值为(652.15±83.47)×10-6 mm2/s、rADC值为0.56±0.08。两组病灶ADC值、rADC值的差异均具有统计学意义(P均<0.001)。应用ADC值鉴别NPC与NPL的曲线下面积为0.943,最佳鉴别阈值为736.5×10-6 mm2/s,敏感度为90.9%,特异度为85.2%;应用rADC值进行鉴别的曲线下面积为0.951,最佳鉴别阈值为634.0×10-6 mm2/s,敏感度为95.5%,特异度为81.5%。结论 DWI、ADC值及rADC值有助于鉴别诊断NPC与NPL。

Objective To explore the value of DWI in differentiation of nasopharyngeal carcinoma （NPC） and nasopharyngeal lymphoma （NPL）. Methods Totally 22 patients with NPC and 27 patients with NPL proved by pathology were retrospectively reviewed, and all of them underwent conventional MRI, DWI and dynamic contrast-enhanced MRI. The signals, mean ADC values, relative apparent diffusion coefficient （rADC） values of each case were reviewed and calculated and compared between the two groups. ROC curves were drawn to evaluate the efficiency of ADC and rADC in differentiation of NPC and NPL. Results NPC and NPL both showed isointensity or slightly hypointensity on T1WI, slightly hyperintensity on T2WI. NPC showed slightly hyperintensity on DWI （b=1000 s/mm^2） and iso-or hypo-intensity on ADC map. NPL showed obvious hyperintensity on DWI （b=1000 s/mm^2） and hypointensity on ADC map. ADC values and rADC values were （842.34±94.66）×10-6 mm2/s and 0.74±0.08 in NPC, （652.15±83.47）×10^-6 mm^2/s and 0.56±0.08 in NPL. The differences of ADC and rADC between NPC and NPL were statistically significant （both P〈0.001）. Taking ADC values to differentiate NPC and NPL, the area under ROC curve was 0.943, the threshold was 736.5×10^-6 mm^2/s, and the sensitivity and specificity was 90.9%, 85.2%, respectively. When rADC values was used for differentiating, the area under ROC curve was 0.951, the threshold was 634.0×10^-6 mm^2/s, and the sensitivity, specificity was 95.5%, 85.2%, respectively. Conclusion DWI, ADC values and rADC values are quite effective in differentiating NPC and NPL.