Nasopharyngeal Mucosa and Adenoids: Appearance at MR Imaging

Abstract

To document the magnetic resonance (MR) imaging appearances of benign nasopharyngeal mucosa and adenoids and to correlate quantitative thickness measurements with histologic findings from nasopharyngeal biopsy specimens. MR imaging studies and nasopharyngeal biopsy specimens were analyzed retrospectively in 100 adults (51 men, 49 women) with benign histologic findings; local institutional review board approval and informed consent had been obtained as part of a previous imaging study. At T1-weighted gadolinium-enhanced MR imaging, the nasopharyngeal roof and adenoid was classified as follows: 1, pencil thin, less than 3 mm; 2, smooth thickening, 3 mm or larger; 3, small tags or stripes; or 4, focal adenoid mass with a vertical striped appearance. The posterior and lateral walls were classified as follows: pattern 1, pencil thin, less than 3 mm; pattern 2, mild thickening, 3 mm or larger with moderate enhancement; or pattern 3, thickening with hypoenhancement along the posterior wall. The frequency of these patterns, as well as cysts, symmetry, and pharyngeal recess patency, were documented. Wall thickness was measured and correlated with age, sex, and histologic findings from biopsy specimens by using Spearman rank correlation and Mann-Whitney U tests. In 100 patients, roof patterns 1-4 were identified in 16 (16%), seven (7%), 33 (33%), and 44 (44%); posterior and lateral wall patterns 1-3 were identified in 20 (20%), 55 (55%), and 25 (25%) patients. Symmetry was identified in 95 (95%) patients, cysts in 41 (41%) patients, and pharyngeal recess patency was identified in 24 (12%) of 200 sides. Roof including adenoid thickness was higher in men (P = .05) and correlated inversely with age (P <.01). In 62 (62%) of 100 patients, biopsy specimens contained lymphoid follicles. Roof including adenoid (P = .01) and posterior wall (P = .03) thickness at MR imaging was higher if follicles were identified in biopsy specimens. Nasopharyngeal hyperplasia has typical MR imaging appearances, including stripes in adenoid bulges and symmetry, which may be useful to differentiate this condition from nasopharyngeal malignancy.