Accuracy of magnetic resonance imaging in predicting absence of fixation of head and neck cancer to the prevertebral space.

BACKGROUND The purpose of this study was to determine the preoperative accuracy of preservation of the retropharyngeal fat plane on magnetic resonance (MR) images in predicting the absence of fixation or extension of head and neck carcinomas to the prevertebral space. METHODS The MR images of 75 patients with T3 or T4 primary pharyngeal or laryngeal cancers seen over a 5-year period and treated at our Head and Neck Cancer Center were retrospectively reviewed. The MR images were independently and blindly evaluated by two head and neck radiologists for preservation of the retropharyngeal fat plane between the tumor and prevertebral musculature. In cases in which the fat was preserved, the prevertebral muscle complex was assessed for the presence of T2 hyperintensity and enhancement. All patients underwent panendoscopy, surgery, or both. RESULTS Forty of 75 patients had preservation of the retropharyngeal fat plane between the tumor and the prevertebral compartment on T1-weighted images. In all 40 cases, the prevertebral muscles had a normal appearance on T2-weighted and enhanced MR images. Intraoperative assessment revealed absence of fixation of tumor to the prevertebral fascia in 39 of 40 cases, and these tumors were resectable. CONCLUSION In patients with advanced head and neck carcinomas, preservation of the fat between the tumor and the prevertebral musculature on unenhanced T1-weighted images reliably predicts absence of prevertebral space fixation.