Inverted Papilloma: CT and MR Imaging Findings in Correlation with Histologic Findings

PURPOSE:To evaluate CT and MR findings suggestive of inverted papilloma by correlation with pathologic findings. MATERIALS AND METHODS: The CT(n=16) and MR(n=8) findings of 22 pathologically proven cases of inverted papilloma in the sinonasal cavity were retrospectively reviewed with reference to location of tumor, density/signal intensity, contrast enhanced appearance, shape and cleft air shadow at the free margin of tumors, and mass effect. These findings and pathologic findings were then correlated. RESULTS: All 22 tumors were located in the unilateral nasal cavity and extended into the maxillary sinus(n=17), choana(n=10), ethmoid sinus(n=8), nasopharynx(n=7), nasal vestibule(n=5) or frontal sinus(n=1). All CT scans showed that the density of tumor masses was similar to adjacent muscle. Precontrast CT scans showed no visibles triations' within the tumor mass, but postcontrast scans revealed striations' of varying degree in six of nine cases. CT scans showed that the free margin of tumors was serrated(n=13) or lobulated(n=5), and in 13 cases cleft air shadow of varying shape was noted. All MR scans showed's triations' with intermediate/slightly high signal intensity on T1WI and intermediate/high on T2WI within tumor masses, which were more prominent on postcontrast scans. On MR, the free margin of tumors was seen to be serrated(n=5), lobulated(n=4), or smooth(n=1), but cleft air shadow was not detected. CONCLUSION: The triations' seen on postcontrast CT and MR images and the cleft air shadow with a serrated appearance seen on CT images at the free margin of tumors suggested the presence of inverted papilloma in the sinonasal cavity.

CT and MR evaluation of Choanal Polyps

PURPOSE: To evaluate the various types and CT and MR imaging findings of choanal polyps. MATERIALS AND METHODS: We classified 42 cases of surgically proven choanal polyps into three types according to site of origin,and retrospectively analyzed imaging findings; in the case of antrochoanal polyps, particulr attention was givento extension of the lesion into the nasal cavity. We also determined whether MR imaging can provide moreinformation than CT. RESULTS: The antrochoanal polyp was the most common type( 33/42 : 78.6% ). Three cases ofchoanal polyps(7.1%) originated in the sphenoid sinus (sphenochoanal polyps), and while six( 14.3% ) did notinvolve the sinus( pure choanal polyps ). Thirty-six of 42 choanal polyps(85.7%) extended into either the choanaor nasopharynx. Three cases of antrochoanal polyps protruded through the middle meatus, and two into theoropharynx. The maxillary sinus component of an antrochoanal polyps extended more frequently through the accessoryostium( 29/33 ) than through the natural ostium. For delineating the stalk of an antrochoanal polyp, MR imagingwas not superior to CT. CONCLUSION: The most common type of choanal polyp is the antrochoanal, followed by purechoanal and sphenochoanal. CT and MR imaging can help identify lesion continuity between a choanal polyp and theparanasal sinus.

Mucocele in Concha Bullosa: A Case Report

Mucocele of concha bullosa is rare and can be misdiagnosed as an intranasal tumor mass. We report a case ofmucopyocele of the concha bullosa.

Normal Value of Mucosal Thickness of Paranasal Sinuses, as Seen on Brain

PURPOSE: To evaluate incidentally observed thickened mucosa of paranasal sinuses on brain MRI of patients without evidence of sinusitis. MATERIALS AND METHODS: We reviewed brain MRI of 82 adults aged over 20 ; 45 were males and 37 were females. Brain axial MRI was obtained from the hard palate with 8mm thickness and 2mm gap. The mucosal thickness of incidentally observed paranasal sinuses seen on brain MRI was measured at the mostly thickened portion by T2- and T1-weighted images. RESULTS: The mean mucosal thickness at the most thickened portion of paranasal sinuses, regardless of their location was 3.5mm with S.D. of 1.5mm. The mucosal thickening was observed more commonly in maxillary (79 patients, mean 3.0mm, S.D. 1.4mm) and ethmoid sinuses (80 patients,mean 2.7mm, S.D. 1.1mm) than in sphenoid (39 patients, mean 1.6mm, S.D. 1.4mm) or frontal sinuses (38 patients, mean 1.9mm, S.D. 1.4mm). CONCLUSION: Mucosal thickening of up to 6.5mm was a common finding on brain MRI of patients without evidence of sinusitis ; accuracy was 95%.