Staging of squamous cell carcinoma of the oral cavity and oropharynx: a comparison of MRI and CT in T- and N-staging.

Our purpose was to assess the accuracy of CT and MRI in staging of squamous cell carcinoma (SCC) of the oral cavity and oropharynx. Fifty-one episodes of primary and recurrent SCC were assessed with CT and MRI. The results were compared with pathological staging. For staging primary tumours, the accuracy of MR was 77% and that of CT was 67%. For detecting recurrent tumour, the accuracy of MR was 89% and that of CT was 100%. For N-staging, nodal sites were divided, according to the site of the primary tumour, into high and low risk. Sensitivity for high risk sites was 60% for clinical assessment, 35% for CT, and 75% for MR. Negative predictive value (NPV) was < or = 50% for all methods. For low risk sites, the NPV was > or = 95% for all methods. For T-staging, MR scanning is overall more accurate than CT. If degraded images and T1 tumours are excluded, the techniques are comparable. MR scanning is oversensitive for recurrent disease. For N-staging, all methods failed to detect small metastatic deposits.