Magnetic resonance imaging of the eustachian tube in nasopharyngeal carcinoma: Correlation of patterns of spread with middle ear effusion

Objective: The purpose of this study was to use multiplanar high-resolution magnetic resonance imaging (MRI) to detail the patterns of tumor spread in nasopharyngeal carcinoma (NPC) and to correlate the findings with the pres ence of an effusion in the middle ear and mastoid. Materials and Methods: Magnetic resonance imaging was performed in 51 patie nts with newly diagnosed NPC, providing 102 individual sides for analysis. Results: Fifty-nine lateral walls of the nasopharynx were involved by NPC. Tumor involved the lateral recess (55). eustachian tube orifice (41), levat or palatini (LP) (32), torus tubarius (TT) (21), pharyngobasilar fascia (38 ), tensor palatini (TP) (17), parapharyngeal fat space (PFS) (19), main bod y of the cartilaginous eustachian tube (CET) (13), bony eustachian tube (0) , middle ear (0), and inner ear (0). Effusions were present in 32 (54%) of the 59 involved sides. Effusions were found to be associated with the follo wing patterns of spread: tumor causing major displacement of the CET withou t invasion (3 of 4), tumor invading TT or LP with minor displacement of the TT (4 of 7) or major displacement of the CET (7 of 7) and advanced invasio n involving the TP, PFS, or CET with major displacement of CET (18 of 19). Effusions were not seen in tumors without invasion that were restricted to the lateral recess or eustachian tube orifice either with no displacement ( 0 of II) or with minor displacement (0 of 11) of the TT. Effusions were pre sent in 28 of 30 cases with major displacement of the main body of the GET, 4 of 18 with minor displacement of the TT, and 0 of 11 with no displacemen t. Displacement of the eustachian tube was a significant factor in the prod uction of an effusion (p < 0.00001) and remained significant even after exc lusion of all cases of advanced invasion (p < 0.0001). Conclusion: The cause of an effusion in NPC is multifactorial. Magnetic res onance imaging has shown invasion of the tensor palatini muscle in patients with an effusion, suggesting a functional cause. However, displacement of the eustachian tube is a significant factor in patients with middle ear and mastoid effusions.