The omega sign refers to the thickened aryepiglottic folds and epiglottis seen in epiglottitis, when the larynx is seen endoscopically or via laryngoscope, and not to the appearance on lateral plain films. CT would show the finding, but placing a child with epiglottitis supine to CT their neck is not only unnecessary but potentially dangerous.
On lateral x-ray of the neck the epiglottis is thickened and appears thumb-shaped rather than the usual thin leaf-like outline (which is called thumb sign).
- 1.Swischuk LE. Imaging of the newborn, infant, and young child. Lippincott Williams & Wilkins. (2004) ISBN:0781734584. Read it at Google Books - Find it at Amazon
- 2. Grover C. Images in clinical medicine. "Thumb sign" of epiglottitis. N. Engl. J. Med. 2011;365 (5): 447. doi:10.1056/NEJMicm1009990 - Pubmed citation