Magnetic resonance imaging-based diagnosis of middle cranial fossa tumors

Abstract

Objective To analyze the magnetic resonance imaging (MRI) features of middle cranial fossa tumors. Methods Thirty-one patients with surgically and pathologically confirmed middle cranial fussa tumors were enrolled in this study, including 13 with trigeminal neurinornas, 6 with meningiomas, 3 with arachnoid cysts, 3 with dermoid cysts, 2 with osteoblastomas, 2 with chordomas, and 2 with epidermoid cysts. All the patients underwent plain and enhanced MR scanning and the imaging data were retrospectively analyzed. Results Different types of middle cranial fossa tumors had distinctly different MRI appearances. Trigeminal neuromas displayed hypo- and iso-intense signals on T1-weighted images (T1WI) and hyperintense signals on T2-weighted images (T2WI), and 9 of the 13 patients presented with shell-shaped enhancement after Gd-DTPA injection. Meningioma showed hypo-and iso-intense signals on T1WI and hypo-, iso- and hyper-intense signals on T2WI, with relatively homogeneous enhancement after Gd-DTPA injection. Osteoblastoma exhibited shell-shaped bony encapsulation of the tumor, and chordomas grew along the middle and posterior cranial fussae with close lateral association with the clivus. Arachnoid cysts and epidermoid cysts showed hypointense signals on TIWI and hyperintense signals on T2WI with slight enhancement of the cyst wall after Gd-DTPA injection. The arachnoid cysts grew expansively, and epidermoid cysts were characterized by high invasiveness in any possible directions. Dermoid cysts presented with hyperintense signals on T1WI and T2WI with popcorn-like appearance in some cases. Conclusion The middle fossa tumors present characteristic MRI features, which, in combination with clinical examinations, help derive an accurate diagnosis. Key words: Middle fossa; Trigeminal neurinoma; Meningioma; Osteohlastoma; Arachnoid cysts; Epidermoid cysts; Dermoid cysts; Magnetic resonance imaging