Diagnostic accuracy of magnetic resonance imaging in the assessment of mandibular involvement in oral-oropharyngeal squamous cell carcinoma: a prospective study.

OBJECTIVE To evaluate the sensitivity, specificity, accuracy, and predictive values of magnetic resonance imaging (MRI) in the assessment of mandibular involvement in oral-oropharyngeal squamous cell carcinoma. DESIGN Prospective study. SETTING University hospital. PATIENTS Forty-three patients with oral or oropharyngeal squamous cell carcinoma undergoing marginal or segmental mandibulectomy between January 1, 1994, and January 31, 2003. INTERVENTIONS Indications for mandibulectomy were MRIs suggestive of bony invasion, tumor involving the retromolar trigone or the alveolar ridge, recurrent or persistent lesion, or intraoperative suspicion of periosteal invasion. Detection of tumor signal replacing the hypointense cortical rim was considered the main radiologic finding for mandibular invasion. MAIN OUTCOME MEASURES The MRI findings were subsequently compared with histopathologic data of surgical specimens with reference to the presence of cortical and/or medullary mandibular involvement. RESULTS Sixteen patients had MRI findings suggestive of mandibular involvement. Segmental mandibulectomy was performed in 15 cases and marginal resection in the remaining case. In 14 patients, bony invasion was confirmed. All of the other 27 patients who underwent marginal or segmental mandibulectomy with negative MRI findings had no histopathologic evidence of mandibular involvement, except in 1 patient: on histopathologic examination, despite cortical integrity, neoplastic vascular embolization into the bony lacunae was detected. Sensitivity of MRI in detecting mandibular involvement was 93%; specificity, 93%; accuracy, 93%; and negative and positive predictive values, 96% and 87.5%, respectively. CONCLUSIONS Magnetic resonance imaging is commonly considered the technique of choice for treatment planning in advanced oral and oropharyngeal squamous cell carcinoma because of its accuracy in depicting soft-tissue involvement. This study demonstrates the additional diagnostic value of MRI in detecting bone invasion.