Lunate trachea is a rare variant of the trachea in inspiration where the trachea has a flattened shape said to resemble a crescent or moon. Normally the tracheal index (ratio of coronal to sagittal diameter) is less than 1, but with lunate trachea the ratio is greater than 1 1, 2.
It is a very specific but poorly sensitive sign of tracheomalacia 1, 3.
- 1. Boiselle PM, Ernst A. Tracheal morphology in patients with tracheomalacia: prevalence of inspiratory lunate and expiratory "frown" shapes. (2006) Journal of thoracic imaging. 21 (3): 190-6. doi:10.1097/01.rti.0000213647.42041.d0 - Pubmed
- 2. Lomasney L, Bergin CJ, Lomasney J, Roggli V, Foster W. CT appearance of lunate trachea. (1989) Journal of computer assisted tomography. 13 (3): 520-2. doi:10.1097/00004728-198905000-00033 - Pubmed
- 3. Boiselle PM, Feller-Kopman D, Ashiku S, Weeks D, Ernst A. Tracheobronchomalacia: evolving role of dynamic multislice helical CT. (2003) Radiologic clinics of North America. 41 (3): 627-36. Pubmed