Frequencies of pleuro-mediastinal lines in healthy subjects

The postero-anterior chest radiograms of 1000 consecutive adults with no evidence of intrathoracic diseases were evaluated and the frequencies of the common pleuromediastinal 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 < .001), right paraspinal line (28-8%, p < .001), left paraspinal line (11-1%, p < .01), anterior junction line (41-21%, p < .01), and posterior lines in the supraazygos area (86-66%, p < .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%. (orig.)