Base of the skull

Magnetic resonance imaging (MRI) has become an essential part of the evaluation of skull base lesions. There are two primary issues that must be addressed by the radiologist. First, the identity of the mass is important. The radiologist used both anatomic location and imaging characteristics to arrive at a best approximation of the diagnosis preoperatively. Second, with the advent of the newer skull base surgical techniques, the precise definition of the extent of a lesion has assumed far greater importance and has provided a further challenge to the radiologist. The paper discusses general concepts about differentiating tumor from the normal structures of the skull base. In particular, the authors focus on the detection of a tumor margin as the tumor spreads either by direct encroachment or by perineural (transforaminal) extension. This paper is also devoted to identifying specific tumor types, using their position and various imaging characteristics as a guide. Finally, brief mention is made of miscellaneous non-neoplastic pathologies