2) Shatzkes DR, Meltzer DE, Lee JA, et al: Sclerosis of the pterygoid process in untreated patients with nasopharyngeal carcinoma. Radiology 2006; 239: 181-186.
3) Roh JL, Sung MW, Kim KW, et al: Nasopharyngeal carcinoma with skull base invasion: a necessity of staging subdivision. Am J Otolaryngol Head Neck Surg 2004; 25: 26-32.
5) Mukherji SK, Weeks SM, Castillo M, et al: Squamous cell carcinomas that arise in the oral cavity and tongue base: Can CT help predict perineural or vascular invasion? Radiology 1996; 198: 157-162.