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[Magnetic resonance and computed tomography compared in the staging of rhinosinusal neoplasms. A cost-effectiveness evaluation].

This study was aimed at comparing CT and MRI in the preoperative staging of sinonasal malignancies and at developing the most cost-effective diagnostic strategy to determinate resectability and choice of surgery and to assess surgical demolition extent. Forty-nine patients with sinonasal tumors were examined during a 10 years' period, with CT (20 patients), MRI (13 patients) and combined CT and MRI (16 patients); 42/49 patients underwent surgical resection (16 patients with craniofacial resection and 6 with orbital exenteration). Cost-effectiveness of the two techniques was assessed comparing five protocols using CT and MRI either alone or combined. In 40/98 orbits the tumor was in contact with a bone wall. MRI was more accurate than CT in assessing orbital invasion (100% sensitivity, 94% specificity, 86% positive predictive value and 100% negative predictive value, vs. 50%, 93%, 75% and 82%, respectively, for CT). MRI showed the tumor in contact with the skull base in 24/49 patients and CT in 23/49 patients, with no statistically significant difference between the two techniques. Dural infiltration, however, was better demonstrated with MRI in 3 patients with minimal bone erosion of the nasal vault. In 5 patients CT and MRI showed pterygopalatine fossa invasion (4 true positives and 1 false positive for both techniques). Since the final decision about orbital exenteration needs accurate surgical mapping, CT appears to yield all the pieces of information necessary for surgical planning. The most cost-effective protocol seems to be a CT examination for all patients. MRI is needed only for better prognostic assessment in the patients with minimal bone erosion of the floor of anterior cranial fossa. In fact, dural invasion, which is a markedly negative factor for survival, may be missed by CT.