MRI、CT和PET-CT检查对鼻咽癌咽后淋巴结转移的诊断价值

背景与目的:三维适形调强放射治疗已成为鼻咽癌放射治疗发展的方向,靶区勾画的精确性显得尤为重要.本研究的目的是探讨MRI、CT以及18F-FDG PET-CT对鼻咽癌咽后淋巴结转移诊断的临床价值,为设计放射治疗计划提供参考.方法:收集2003年1月至2005年4月间中山大学肿瘤防治中心放疗科收治、经病理证实的初诊鼻咽癌87例,所有病例同时具有治疗前鼻咽和颈部的MRI、增强CT及PET.CT检查资料.在MRI、CT及PET-CT上分别评价鼻咽癌咽后淋巴结转移的检出率,比较采用χ2检验.结果:174侧(87例患者)咽旁间隙中,MRI、CT和PET-CT对鼻咽癌咽后淋巴结转移的检出率分别为44.8%、33.9%和24.1%.MRI对鼻咽癌咽后淋巴结转移的检出优于CT(P=0.037).MRI及CT对鼻咽癌咽后淋巴结转移的检出率高于.PET-CT,其差异均有统计学意义(P＜0.001,P=0.002).咽后淋巴结的最小径与PET-CT的标准摄取值呈正相关(r=0.832,P＜0.001).结论:MRI对咽后淋巴结转移的检出率高于CT及PET-CT.在鼻咽癌的三维适形调强放射治疗中,三者的结合应用将有利于提高靶区勾画的精确度.

The values of MRI, CT, and PET-CT in detecting retropharyngeal lymph node metastasis of nasopharyngeal carcinoma

BACKGROUND & OBJECTIVE: Three-dimensional conformal and intensity-modulated radiotherapy is the direction of developing radiotherapy for nasopharyngeal carcinoma (NPC). The accuracy of target area outlines is especially important. This study was to explore the clinical diagnostic values of magnetic resonance imaging (MRI),computed tomography (CT),and 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)-CT in detecting retropharyngeal lymph node metastasis of NPC,and to provide references to the plan of radiotherapy. METHODS: MRI,enhanced spiral CT,and PET-CT reports of the nasopharynx and whole neck of 87 naive NPC patients,histologically diagnosed and treated in Cancer Center of Sun Yat-sen University between Jan. 2003 and Apr. 2005,were analyzed. The detection rates of retropharyngeal lymph node metastasis were compared among MRI,CT and PET-CT using Chi-square test. RESULTS: Among the 174 parapharyngeal spaces of the 87 patients,the detection rates of retropharyngeal lymph node metastasis by MRI and CT were significantly higher than that by PET-CT (44.8% and 33.9% vs. 24.1%,P < 0.001 and P = 0.002). As compared with CT,MRI played an advantage in detecting retropharyngeal lymph node metastasis of NPC (P = 0.037). The minimal axial diameter of retropharyngeal lymph node was positively correlated to the standard uptake value (SUV) of PET-CT (r = 0.832,P <0.001). CONCLUSIONS: MRI are better than CT and PET-CT in detecting retropharyngeal lymph node metastasis of NPC. The combination of MRI,CT,and PET-CT is useful for delineating targets accurately in 3-dimensional conformal intensity-modulated radiotherapy for NPC.