Impact of Computed Tomography and Magnetic Resonance Imaging on Staging for Nasopharyngeal Carcinoma

[Purpose] To compare the differences between computed tomography(CT) and magnetic resonance imaging(MRI) on defecting disease extent and the effect of T staging in nasopharyngeal carcinoma(NPC).[Methods] Eighty-four cases with nasopharyngeal carcinoma pathologically proved who performed CT and MRI examination at the same time or during a short time(no more than two weeks) before the treatment were retrospectively analyzed.χ2 test was used to compare the detective rate of every anatomical position by these two kinds of imaging methods.According to the '92 staging standard of NPC,the patients were staged by CT plus clinical examination and by MRI plus clinical examination.χ2 test was used to compare the composition of various stages divided by these two kinds of imaging methods.[Results] The incidence rates of cranial bone damage diagnosed by CT and MRI were 11.9% and 41.7% respectively,with statistical significance(χ2=18.970,P=0.000).The incidence rates of encroachment of cavernous sinus diagnosed by CT and MRI were 8.3% and 20.2% respectively,which was of statistical significance(χ2=4.861,P=0.027).To the T staging,the composition of various stages divided by these two kinds of imaging methods was of statistical significance(χ2=16.416,P=0.001).There were 31 patients(36.9%) whose T stages changed between CT and MRI,while there were more advanced stage patients(Ⅲ and Ⅳa) diagnosed by MRI than those by CT.[Conclusion] The detecting rates of cranial bone damage and encroachment cavernous sinus detected by MRI are higher than those by CT.MRI can elevate the T staging for NPC.