Sleep apnea is often caused by obstruction of the pharyngeal airway. The goal of this study was to use ultrafast MR imaging to examine the pharyngeal airway in patients with sleep apnea and to evaluate the usefulness of this technique for localizing the site of obstruction.

Fifteen patients with sleep apnea and five healthy volunteers underwent ultrafast MR imaging while awake and during sleep induced with hydroxyzine hydrochloride. Sequential midline sagittal images of the pharynx were obtained and displayed in the cine mode.

Patients with sleep apnea were found to have sites of pharyngeal abnormality that were not present in healthy volunteers. Nine sites of narrowing in seven patients (47%) were detected with the patient awake; 21 sites of obstruction in 13 patients (87%) were diagnosed with the patient asleep. Six patients showed only one obstruction, and seven had several obstructions: five had obstructions at the velum palatinum and at the oropharynx; one had obstructions at the velum palatinum, oropharynx, and hypopharynx; one had obstructions at the velum palatinum and the hypopharynx. The sites of narrowing during wakefulness and the sites of obstruction during sleep were the same in only four (31%) of the patients with pharyngeal airway obstruction.

Ultrafast MR imaging is useful for localizing the sites of pharyngeal airway obstruction in patients with sleep apnea.