Nasopharyngeal carcinoma: the impact of CT-scan and of MRI on staging, radiotherapy treatment planning, and outcome of the disease.

The present study is a critical review of the role of computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis and therapy of nasopharyngeal cancer. It is estimated that following CT-scan/MRI, T,N staging of the disease changes in about half of cases, which results in important adjustments of the radiotherapy treatment planning, both in terms of radiation field dimensions and of dose specifications. The development of novel technology with CT-scan-simulated 3-D conformal or intensity-modulated radiotherapy (IMRT) planning is gradually becoming the standard therapy for nasopharyngeal carcinoma (NPC). CT-scan/MRI is also of value in detecting massive parapharyngeal involvement, low-neck lymphadenopathy or fixation of nodes onto adjacent structures, which are important features indicating the necessity to integrate chemotherapy or surgical neck dissection in the overall treatment policy. CT-positron emission tomography (PET) scan is recently under evaluation for the identification of the most active tumor regions, which will allow a biological radiotherapy planning (RTP) using IMRT techniques.