Defining normal upper airway motion in asymptomatic children during sleep by means of cine MR techniques

PURPOSE: To define normal upper airway motion in asymptomatic children during sleep by means of dynamic cine magnetic resonance (MR) techniques. MATERIALS AND METHODS: In children referred for MR of the brain who required sedation, a sagittal midline cine MR sequence was performed. Motion of the nasopharynx, oropharynx, and hypopharynx was characterized as static patent, dynamic patent, intermittent collapse, or static collapsed; maximal diameter and greatest change in size were calculated in millimeters. Mouth position (open or closed) was determined. Parameters were compared with age (t test) and mouth position (Fisher exact test). RESULTS: In the 148 subjects (mean age, 3.4 years), the nasopharynx showed dynamic motion in 53 (36%). The oropharynx was most commonly collapsed in 98 (66%) of the patients. The hypopharynx showed dynamic motion in 72 (49%) of the patients and was never collapsed. Vertical motion was present in 77 (52%) of the patients. The mouth was open in 96 (65%) of the patients. There was a statistically significant correlation between mouth position and dynamic motion in the oropharynx (P = .006) and in the nasopharynx (P < .006) but not in the hypopharynx (P = .655). CONCLUSION: Dynamic changes in diameter were often seen in the nasopharynx and in the hypopharynx of asymptomatic sleeping children. However, collapse of the hypopharynx was not normally encountered. (C) RSNA, 2002.