Unable to refine study measurements/protocol adequately.

There is a fundamental gap in the investigators ability to design effective surgical treatment of obstructive sleep apnea (OSA) for the 30-40% of patients who cannot tolerate non-surgical treatment. OSA surgery outcomes vary widely, with the chances of a successful outcome ranging from 5% to 65% for individual or combination procedures. To predict - and thereby to improve - outcomes, the investigators must determine what predicts surgical success. This project will compare findings from two evaluations: drug-induced sleep endoscopy (DISE) and upper airway magnetic resonance imaging (MRI). DISE has demonstrated important benefits, but it has important limitations. Upper airway MRI is the most complete evaluation performed during wakefulness, making it conducive to broad application and less expensive than DISE, but there are no studies utilizing MRI as a surgical evaluation. The investigators propose a cross-sectional analysis of 40 adult subjects with moderate to severe OSA. In addition to history, physical examination, and polysomnogram (sleep study), all subjects will undergo DISE and MRI to characterize the pattern of obstruction. The investigators will examine the association between DISE and MRI, focusing on specific DISE findings that have been associated with surgical outcomes. The investigators multidisciplinary team has substantial expertise and experience in OSA investigation, DISE, and upper airway MRI.

Inclusion Criteria:

• age ≥ 21 years; moderate to severe OSA (AHI ≥15 events/hour)
• body mass index <40 kg/m2.

Exclusion Criteria:

• prior OSA surgery
• known neurologic, cardiac, pulmonary, renal, or hepatic disorders
• psychiatric problems except for treated depression or mild anxiety
• co-existing sleep disorder other than OSA
• other contraindication to DISE or MRI such as propofol allergy.

Study participants will be adults with obstructive sleep apnea undergoing surgery. All participants will undergo magnetic resonance imaging (MRI) and drug-induced sleep endoscopy (DISE).