Objectives: The aims of the study were to determine the predictive imaging findings of extranodal extension (ENE) in metastatic cervical lymph nodes of head and neck squamous cell carcinoma and to investigate the interobserver agreement among radiologists with different experience levels.
Materials and methods: Patients with cervical lymph node dissection and who had metastatic lymph nodes and preoperative imaging were included. Three radiologists evaluated nodal necrosis, irregular contour, gross invasion, and perinodal fat stranding. They also noted their overall impression regarding the presence of the ENE. Sensitivity, specificity, odds ratios based on logistic regression, and interobserver agreement of ENE status were calculated.
Results: Of 106 lymph nodes (that met inclusion criteria), 31 had radiologically determined ENE. On pathologic examination, 22 of 31 nodes were positive for ENE. The increasing number of metastatic lymph nodes was associated with the presence of the ENE ( P = 0.010). Irregular contour had the highest sensitivity (78.6%) and gross invasion had the highest specificity (96%) for the determination of the ENE. The radiologists' impression regarding the presence of the pathlogical ENE had 39.3% sensitivity and 82% specificity. Metastatic lymph nodes with a perinodal fat stranding and with the longest diameter of greater than 2 cm were found to be strong predictors of the ENE. The gross invasion demonstrated the highest κ value (0.731) among the evaluated imaging criteria.
Conclusions: In the assessment of ENE, the gross invasion had the highest specificity among imaging features and showed the highest interobserver agreement. Perinodal fat stranding and the longest diameter of greater than 2 cm in a metastatic lymph node were the best predictors of the ENE.
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