[Magnetic resonance imaging analysis of regional lymph node metastasis in 1 298 cases of nasopharyngeal carcinoma].

OBJECTIVE

Regional nodal metastasis in nasopharyngeal carcinoma plays an important role in the definition of radiotherapy area and clinical stage. It is also one of the main factors influencing prognosis. This study was designed to explore the pattern of metastatic lymph nodes for patients with nasopharyngeal carcinoma, which might provide a basis for clinical treatment and research.

METHOD

From Jan. 2009 to Jul. 2011, 1 298 histologically diagnosed nasopharyngeal carcinoma patients had routine MRI scan before radiotherapy in The First Affiliated Hospital of Guangxi Medical University. Diagnostic radiologists and radiation oncologists together assessed the nodal distribution according to the guideline CT-based delineation of lymph node levels. Then,Chi-square test was used to analyze the correlations between T stage and nodal metastasis rate and between nodal diameter and nodal extracapsular invasion.

RESULT

Of 1298 patients, 1067 (82.2%) had nodal involvement. The distributions were as: 20 in level I b,604 in level II a,883 in level II b,330 in level III, 78 in level IV, 162 in level Va,49 in level Vb,967 in retropharynx. Leap metastasis rate was 0.69%. In these patients, a total of 2464 positive nodes,including 1589 (64.52%) extra capsular spread nodes, were detected. The rate of nodal extracapsular invasion was higher when the axial diameter increased. No significant correlation was found between T stage and nodal involvement.

CONCLUSION

The level II and retropharyngeal node are the most frequently involved regions. They have similar metastatic rate and are both the first echo node to metastases of nasopharyngeal carcinoma. Level I metastasis is very low. There is a positive correlation between the proportion of extracapsular spread of metastatic lymph nodes and the axial diameter of lymph nodes. The cervical node involvement of nasopharyngeal carcinoma spread orderly down the neck, and the incidence of skip metastasis is rare. There is no significant difference between T stage and nodal involvement.