title: The posterior tracheal band in the lateral chest radiograph.
abstract: The appearance and variations of the posterior tracheal band (PTB) was studied from 406 upright chest radiographs, taken from 293 individuals of varying age. PTB is visualized in about 80% of individuals well enough to be diagnostically useful. Its average width is 3 mm, and patient positioning can cause variations not exceeding 2 mm. Progressive widening by 2 mm or more, blurring of previously sharp margins or an overall width exceeding 5 mm should be considered suggestive of mediastinal or related abnormality.
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D011859:Radiography; D014132:Trachea / Q000033:anatomy & histology / Q000000981:diagnostic imaging*