Imaging of sino-nasal inverted papilloma: How can we emphasize the usefulness of the “striated pattern” sign?

Abstract

Abstract Background Inverted papilloma (IP) is an uncommon sino-nasal neoplasm with potentially distinctive MRI and CT features. The MR “striated” imaging pattern has been reported as a valuable MR imaging feature of IP. The purpose of this study was to validate the usefulness of this sign using detailed criteria of the sign itself. Results All imaging findings were described for 16 patients in descriptive pattern. The nasal involvement showed highest prevalence followed by the maxillary sinus. The bony changes include remodeling and defects (n = 6), remodeling only (n = 4), and None (n = 6). Changes were severe 1/10, moderate in 3/10, and mild 5/10. Focal hyperostosis was seen in six. A striated pattern was “diffuse” in all 16 (100%) of the IPs; it followed a certain direction in all 16 patients: divergent (n = 6), convoluted (n = 2), and parallel (n = 8). Divergent growth from focal hyperostosis was seen (n = 4). Visibility of the sign was superior in T2 images (n = 11), superior in enhanced images (n = 3), and equal in both (n = 2). Conclusions The striated pattern is a reliable MR imaging feature of sino-nasal IPs. Validity and usefulness of this sign can be emphasized by defining parameters of the signs itself including the following: diffusivity, direction of striations and relation to hyperostosis, and comparing visibility in both T2 and GAD-enhanced images, as well as combining this imaging signature with remolding bony changes < 1.5.