Infratemporal Fossa, Masticator Space and Parapharyngeal Space: Can the Radiologist and Surgeon speak the Same Language?

Imaging is an integral part of head and neck cancer staging and assessing resectability. Accurate perception of imaging information by the clinician is possible only by effective communication between radiologist and surgeon. Traditionally, the radiologist studies the head neck region with two dimensional cross-sectional imaging. The surgeon perceives the head and neck region by real-time experience at surgery as a threedimensional (3D) space. Advances in computed tomography (multidetector CT) provide multiplanar and 3D reformations as added tools to facilitate understanding the complex anatomy and pathology and improve accuracy in staging. Despite these aids, accurate information requires a precise understanding of the different nomenclature of suprahyoid spaces used by the radiologist and clinician. While clinicians are familiar with infratemporal fossa (ITF), radiologists are familiar with masticator space (MS). Although these have been used interchangeably in the staging systems, the subtle difference needs to be understood. Literature also has differing definitions of the parapharyngeal space (PPS). This article describes these spaces, the varied definitions of PPS and the implications of involvement of structures of the ITF and MS on T staging of head neck cancers. A practical approach to the differential diagnoses of parapharyngeal lesions is also described.