18F-FDG PET/CT形态特征及代谢参数在鼻咽淋巴瘤与鼻咽癌鉴别中的价值

The significance of 18F-FDG PET/CT morphological characteristics and metabolic parameters in the differential diagnosis of nasopharyngeal lymphoma and nasopharyngeal carcinoma

目的探讨18F-FDG PET/CT形态特征及代谢参数在鼻咽淋巴瘤与鼻咽癌鉴别诊断中的价值。方法回顾性分析16例鼻咽部淋巴瘤(nasopharyngeal lymphoma,NPL)(NPL组)和21例鼻咽癌(nasopharyngeal carcinoma,NPC)(NPC组)患者的PET/CT图像资料。形态学上,两组鼻咽部病灶分布特点、累及颅底骨、扁桃体及腮腺、副鼻窦及鼻腔、颈部淋巴结差异分别用χ2检验进行统计分析;代谢参数上,两组鼻咽部病灶的代谢参数[最大标准化摄取值(maximum standardized uptake value,SUVmax)、42%及50%阈值肿瘤代谢体积(metabolic tumor volume,MTV42%、MTV50%)、总葡萄糖酵解量(total lesion glycolysis,TLG)]分别进行Mann-Whitney秩和检验。结果形态上,NPL及NPC两组PET/CT图像均可表现鼻咽部软组织增厚,NPC以局灶型多见,而NPL以弥漫型多见(14.3%vs 56.3%,P<0.05);NPC更容易累及颅底骨(33.3%vs 0%,P<0.05)。而NPL一般为双侧颈部淋巴结受累多见,NPC双侧少见(68.8%vs 19.0%,P<0.05)。与NPC相比,NPL更易累及鼻腔或副鼻窦(19.0%vs 25.0%,P=0.71)及扁桃体或腮腺(4.8%vs 50%,P<0.05)。基于以上特征,本研究中PET/CT诊断NPL及NPC总的准确率为91.9%。代谢参数上,NPL与NPC病灶的SUVmax、MTV42%、MTV50%、TLG分别为7.18(5.16,9.18)、8.20(6.04,10.35),7.51(3.57,11.50)mm3、7.59(1.51,12.61)mm3,5.22(2.08,7.19)mm3、7.12(1.12,10.69)mm3,37 025(20 356.3,78 568.6)、41 744(45 257.1,80 719.2),差异均无统计学意义(P=0.592、0.874、0.475、0.980)。结论 18F-FDG PET/CT在NPL与NPC的鉴别诊断中具有重要价值。根据PET/CT的影像形态特征综合判断的准确率较高。病变代谢参数(SUVmax、MTV42%、MTV50%、TLG)均不能作为两者的鉴别要点。

Objective To investigate the significance of morphological characteristics and metabolic parameters of 18F-FDG PET/CT in the differential diagnosis of nasopharyngeal lymphoma and nasopharyngeal carcinoma. Methods The PET/CT images of 16 cases of nasopharyngeal lymphoma(NPL) and 21 cases of nasopharyngeal carcinoma(NPC) were retrospectively analyzed. Morphologically, the differences in distribution characteristics of nasopharyngeal lesions, and involvements in skull base bone, tonsil, parotid gland, paranasal sinus, nasal cavity and neck lymph nodes were statistically analyzed using chi-suqare test. The metabolic parameters(SUVmax, MTV42%, MTV50% and TLG) of nasopharyngeal lesions between the two groups were tested by Mann-Whitney rank test. Results PET/CT images in both NPL and NPC showed nasopharyngeal soft tissue thickening. NPC was more common in focal type, while NPL was more common in diffuse type(14.3% vs. 56.3%, P<0.05). NPC was more likely to involve the skull base(33% vs. 0%, P<0.05). However, NPL was commonly involved in bilateral cervical lymphomas, and NPC was rare in both sides(68.8% vs.19.0%, P<0.005). Compared with NPC, NPL was more likely to involve nasal cavity or paranasal sinus(19.0% vs. 25.0%, P<0.71) and tonsil or parotid gland(50% vs. 4.8%, P<0.05). The total accuracy of PET/CT in the diagnosis of NPL and NPC was 91.9%. The medians of SUVmax, MTV42%, MTV50% and TLG in NPL lesions were 7.18(5.16, 9.18), 7.51(3.57, 11.50)mm3, 5.22(2.08, 7.19) mm3 and 37 025(20 356.3, 78 568.6), respectively;and in NPC lesions were 8.2(6.04, 10.35), 7.59(1.51, 12.61)mm3, 7.12(1.12, 10.69)mm3, 41 744(45 257.1, 80 719.2), respectively. There was no significant difference was revealed between two groups(P>0.05). Conclusion 18F-FDG PET/CT plays an important role in the differential diagnosis of NPL and NPC. The accuracy of comprehensive judgment based on the morphological features of PET/CT is high. The metabolic parameters of the lesions cannot be used as the key points for differential diagnosis.