鼻咽癌咽后淋巴结转移磁共振诊断标准的研究

目的探讨鼻咽癌咽后淋巴结转移的合适诊断标准。方法275例初治鼻咽癌进入本研究。所有患者抗肿瘤治疗前行磁共振(MRI)检查,测量咽后淋巴结的最长和最短轴径,并依据MRI随访结果对淋巴结进行定性评价。分析受试者工作特性曲线(ROC曲线)确定诊断咽后淋巴结转移的合适轴径和界值。结果275例患者共检出468个咽后淋巴结,经随访240个为阳性,228个为阴性。阳性与阴性淋巴结的最短轴径值分别为9.9mm±4.8mm和3.3mm±1.2mm(P<0.01),而最长轴径值分别为12.9mm±5.8mm和5.7mm±2.0mm(P<0.01)。在各轴径值中,以最短轴径≥6mm作为咽后淋巴结转移的诊断标准最为合适,此时敏感性为84.1%,特异性为94.3%,准确率为89.1%。50个存在中心坏死的淋巴结中,最短轴径<6mm的有3个。辅加淋巴结存在中心坏死作为转移诊断标准,可稍提高敏感性。结论以最短轴径≥6mm和淋巴结存在中心坏死作为鼻咽癌咽后淋巴结转移的诊断标准更科学。

Radiologic criteria of MRI in diagnosing retropharyngeal lymph nodal metastasis of nasopharyngeal carcinoma

OBJECTIVE: To explore the reasonable radiologic criteria of retropharyngeal lymph nodal (RLN) metastasis of nasopharyngeal carcinoma (NPC). METHODS: 275 patients with newly diagnosed NPC were enrolled. All patients underwent Magnetic resonance imaging (MRI) before treatment to measure the sizes of maximal and minimal axial diameters of each node. Determination of malignancy was based on the results of MRI follow-up. Receiver operating characteristic (ROC) curve was used to determine the optimal axial diameter and cutoff size criterion of RLN metastasis. RESULTS: Among the 275 patients, a total number of 468 RLNs were assessed. 240 positive and 228 negative nodes were later confirmed by the MRI follow-up. The mean sizes of minimal and maximal axial diameters for positive nodes were significantly higher than those for negative nodes (9.9 mm +/- 4.8 mm vs 3.3 mm +/- 1.2 mm, 12.9 mm +/- 5.8 mm vs 5.7 mm +/- 2.0 mm, all P < 0.01). The reasonable criterion for diagnosing RLN metastasis was the minimal axial diameter of > or = 6 mm. The sensitivity, specificity and accuracy of this criterion were 84.1%, 94.3% and 89.1%, respectively. There were 3 nodes whose minimal axial diameter was < 6 mm in 50 RLNs with central necrosis. Central necrosis combined with the minimal axial diameter criteria slightly increased the sensitivity at a stable specificity. CONCLUSION: The reasonable radiologic criteria for assessing RLN metastasis of NPC are: (1) node with a minimal axial diameter > or = 6 mm; and (2) any node with central necrosis.