Contrast-enhanced CT and MRI for detecting neck metastasis of oral cancer: comparison between analyses performed by oral and medical radiologists.

OBJECTIVES: The aim of the study was to verify the concordance of contrast-enhanced CT (CECT) and MRI evaluation among four radiologists in detecting metastatic cervical lymph nodes of oral cancer patients.
METHODS: Ten patients underwent clinical and imaging examinations (CECT and MRI). Four radiologists, two oral and maxillofacial radiologists (OMRs) and two medical radiologists (MRs), independently analysed the images twice. Cohen's kappa index and Wilcoxon signed-rank test were used to verify the concordance between all analyses.
RESULTS: Regarding the interobserver agreement, the OMRs presented excellent kappa values for determining the regional lymph nodes (N-stage) in both CECT and MRI. The MRs presented moderate agreement for CECT evaluation at the first reading, but no concordance was found for the other analyses. When each imaging modality was analysed separately, kappa values were higher between all examiners. Greater variability was demonstrated between N-stage evaluation using different examinations. All radiologists were able to identify a greater number of metastatic lymph nodes in CECT than in MRI, except one MR, but no significant difference was found for all readers. The differences between the number of metastatic lymph nodes among all radiologists were not statistically significant. Moderate intraobserver agreement was observed for CECT and MRI evaluation, except for one MR.
CONCLUSIONS: The differences found between the N-stage performed by OMRs and MRs support the necessity of a multidisciplinary approach in the imaging evaluation of metastatic nodes. Further studies are necessary to confirm which imaging modality should be employed when evaluating neck areas.