VALUE OF MAGNETIC-RESONANCE-IMAGING IN STAGING CARCINOMAS OF THE ORALCAVITY AND OROPHARYNX

The value of magnetic resonance imaging (MRI) in preoperative tumor (T ) staging was assessed prospectively in 46 patients with malignant car cinomas of the oropharynx and oral cavity. In each case, the MRI findi ngs were compared with the preoperative clinical and postoperative his topathologic findings. MRI showed an accuracy of 890/. in identifying the T stage, as compared with the histopathologic result. The accuracy of the clinical examination was 78%. Compared with the clinical exami nation, MRI is particularly suited for differentiating T3/T4 and the l arger T2 tumors. MRI tends to overinterpret the T stage when the neigh boring tissues are inflamed or edematous, as it allows no demarcation between inflamed or edematous tissue and tumor. Moreover, normal oroph aryngeal mucous membrane and intrinsic tongue muscle both absorb contr ast medium. In the clinical examination, the T stage is often underest imated, as the depth of infiltration and bone involvement cannot alway s be determined with certainty. The ability of MRI to give an axial, c oronal, and sagittal image allows an exact preoperative view of tumor spread and assessment of infiltration into adjacent structures.