Images in Radiology - MRI in Sleep Apnoea

A 37-year-old man with a body mass index of 39 kg/m², presented with hypersomnia during daytime and snoring during sleep. The central nervous system examination and indirect laryngoscopy revealed no abnormality. Polysomnography suggested the diagnosis of obstructive sleep apnoea. Mean arterial oxygen saturation was 89%, while minimum arterial oxygen saturation was 53%. The oxygen desaturation per hour was 20.6. Apnoea-hypopnea index was 17/hour. Subsequently, an MRI of upper airway was performed in awake and asleep state. The pharyngeal airway was imaged in the median sagittal and axial planes using a 0.5T MR. Spin echo T1-weighted images revealed no abnormality (Figure 1). Diazepam (5 mg) was given intravenously and imaging was repeated during the episode of apnoea. The pharyngeal airway became T-shaped due to the collapse of lateral pharyngeal walls (Figure 2). The figure demonstrates narrowing of the lumen to the extent of 70% as compared to dimensions in the wakeful state.