[MRI analysis of paranasal sinus invasion in 182 patients with nasopharyngeal carcinoma].

Objective: The aim of the study was to analyze the nuclear magnetic resonance image (MRI) findings for invasion of paranasal sinuses in patients with nasopharyngeal carcinoma (NPC) and to improve the understanding of its MRI diagnosis.

Methods: The MRI data of 182 patients with nasopharyngeal carcinoma and paranasal sinus invasion were retrospectively analyzed.

Results: One hundred and eighty-two patients developed paranasal sinus invasion, of which, the incidence of sphenoid sinus invasion was highest. The MRI findings of paranasal sinus invasion of patients with NPC were as follows: 100%, 95.6% and 56.6% patients revealed damage of sinus wall, uneven thickening of mucosa, masses of the sinus cavity connected with the primary tumor of nasopharynx, and all the lesions presented iso- or slightly hypo-intense signal on T1WI and iso- or slightly hyper-intense signal on T2WI and significantly heterogeneous enhancement after contrast administration, which were consistent with the primary tumor of the nasopharynx regarding to the signal intensity and reinforcement schedule. 77.5% patients presented massive sinus cavity effusion. T2-weighted images are excellent in differentiating high signal intensity thickened mucosa or retained secretions from relatively lower signal intensity tumor. In contrast-enhanced MRI, tumor with solid enhancement can be differentiated from thickened mucosa related to inflammation with a thin superficial enhancement. 96.5% and 94.7% patients with maxillary sinus invasion and ethmoid sinus invasion were detected with the contrast enhanced axial T1-weighted MR imaging respectively, which were higher than those with the non-enhanced axial T1 and T2 imaging (88.4% and 77.9% for maxillary sinus invasion; 65.8% and 73.7% for ethmoid sinus invasion), the differences were statistically significant (P < 0.05 for all comparison). All patients with sphenoid sinus invasion were detected with the contrast enhanced sagittal T1-weighted MR imaging.

Conclusion: Multiplanner MR scan and enhanced scan can improve the diagnosis of invasion of paranasal sinuses in patients with NPC. The MRI findings of patients with NPC with paranasal sinus invasion include sinus wall damage; unevenly thickening mucous membrane of sinuses; tumors in sinus cavity connective with the primary tumor of nasopharynx , or with massive sinus cavity effusion. The T2-weighted sequence and contrast enhanced sequence are conducive to differential diagnosis of inflammatory changes from neoplastic tissues. The enhanced axial T1-weighted section and the enhanced sagittal T1-weighted section are most helpful to detection of maxillary sinus, ethmoid sinus invasion and sphenoid sinus invasion, respectively.