MR Findings of Nasal Cavity Lesions Showing the Infundibular Widening on CT

PURPOSE: Several kinds of nasal cavity lesions located in the region of the infundibulum on CT. At such time,the visualization of these lesions is very sinilar. The purpose of this study was to differentially diagnose thesenasal cavity lesions through evaluation of the MR findings. MATERIALS AND METHODS: In 51 cases of pathologicallyproven nasal cavity masses which on CT showed infundibular widening, we retrospectively evaluated the MR findings.The cases involved prolapsed antral mucosa from sinusitis(n=15), inverted papilloma(n=10), antrochoanalpolyp(n=10), aspergillosis(n=9), and nasal polyp(n=7). All patients underwent both CT and MR. imaging. RESULTS: In all cases, CT findings were similar ; soft tissue masses filling the maxillary sinus and nasal cavity wereassociated with infundibular widening caused by pressure on the uncinate process, leading to erosion. Differentialdiagnosis by CT was very difficult ; MR T2 weighted imaging was most effective for differential diagnosis of thesenasal cavity masses. Prolapsed antral mucosa showed central inhomogeneous mixed signal intensity, with aperipheral rim of hyperintensity along the sinus wall and nasal component. Antrochoanal polyps showed homogeneousbright signal intensity of the antral and nasal component. Aspergillosis showed central dark signal foci. Invertedpapillomas showed mixed intermediate and high intensity mixed with high signal intensity. Nasal polyps showedstriation mixed of intermediate and high signal intensity, while nasal polyp showed striation of intermediate andhigh intensity. On Gd-enhanced T1 weighted images, prolapsed antral mucosa and antrochoanal polyp showedperipheral rim enhancement of the antral and nasal component. In contrast, inverted papilloma and nasal polypshowed intense enhancement of the mass and can be separate from the sinus inflammatory disease. CONCLUSION: Various nasal cavity masses showing infundibular widening on CT can be differentiated on MR images, especially ofthese are T2 weighted or contrast enhanced T1 weighted.

Evaluation of the Dynamic Patency of the Frontonasal Duct: Value of PNS CT Scan after Administration of anlsoosmolar Contrast Agent for Low lrritation into the Nasal Cavity

PURPOSE: To evaluate the dynamic patency of the frontonasal duct(FND) on PNS CT scan after administration ofan iso-osmolar contrast agent (lsovist) into the nasal cavity. MATERIALS AND METHODS: Coronal PNS CT scans from ten normal and 30 patients with symptoms of chronic sinusitis were obtained after administration of lsovist intothe nasal cavity, followed by Valsalva maneuver for the even distribution of the agent into the FND and sinuses. Atotal of 80 FNDs were evaluated for dynamic patency by examining the presence of the contrast agent in ducts. RESULTS: The contrast agent was visualized in 34/37 FNDs(91.9%) without ipsilateral frontal sinus it is and was visualized in 18/43 FNDs(41.9%) in cases of ipsilateral frontal sinusitis. In addition, the contrast agent within the ipsilateral frontal sinus was visualized in 8/18 FNDs(44.4%). The major causes of ductal obstruction were mucoperiosteal thickening and polypoid lesions secondary to inflammation. CONCLUSION: PNS CT scan together with the administration of lsovist, which caused minimal irritation, was useful for the evaluation of the relationship between the dynamic patency of the FND and frontal sinusitis, In addition, this study can provide the rhinologist with accurate anatomical and pathological information concerning the FND before a choice is made between endoscopic sinus surgery or medical treatment.