[Frequencies of pleuro-mediastinal lines in healthy subjects. A contribution to the knowledge of the normal roentgen anatomy of the mediastinum (author's transl)].

The postero-anterior chest radio-grams of 1.000 consecutive adults with no evidence of intrathoracic diseases were evaluated and the frequencies of the common pleuro-mediastinal lines in four age groups were calculated. The following lines are less frequent in the age (percentages in the youngest group, ages 18-25, and the oldest group, ages 41-65, respectively): posterior lines in the infra-azygos area (51-19%, p less than .001), right paraspinal line (28-8%, p less than .001), left paraspinal line (11-1%, p less than .01), anterior junction line (41-21%, p less than 0.1), and posterior lines in the supraazygos area (86-66%, p less than .05). The incidences of the right paratracheal stripe (76%), of the aortic nipple (4%) and of the double-contour in the supra-aortic area (51%) were independent from age. The physiologic variations of these lines are discussed. The posterior boundaries of the lung in the supraazygos area manifest as a right pleuro-esophageal line (36%) or as a posterior junction line (64%). A small sickle-like pleuro-esophageal stripe is found in 9%.