Gd-DTPA enhanced MR for detecting intracranial extension of sinonasal malignancies.

Magnetic resonance imaging is frequently used for evaluating the extent of malignant tumor in the paranasal sinuses and nasal fossa. Detection of the intracranial extension of a tumor is important in the initial staging of disease. The epidural component of a sinonasal tumor frequently displays signal intensity at or near that of the adjacent brain on standard T1- and T2-weighted scanning sequences. In six of eight malignant sinonasal tumors with intracranial involvement, gadopentetate dimeglumine (Gd-DTPA) enhanced MR was significantly better than the noncontrast scans for demonstrating the intracranial extension. This finding is in contradistinction to the superiority of unenhanced T2-weighted scans for determining the extent of disease within the sinonasal region itself. Tangential Gd-DTPA MR scanning of the skull base compensates for the difficulty of recognizing areas of bone destruction on noncontrast images. Postcontrast sequences should be added to the scanning protocol for sinonasal lesions near the skull base.