The subcarinal space revisited on a frontal chest radiography. An evaluation in subcarinal mass detection

Subcarinal space lucency is visible on a routine frontal chest high kvp radiography because of a double density gradient (vertical and horizontal). Results obtained in the first part of the study concerning 300 normal subjects show that the vertical density gradient is visible in 83% of cases, the horizontal gradient in 93% and both gradients in 76%. The right internal bronchial stripe (RIBS) is inconstant and visible on the three segments of the right bronchial tree in only 31% of cases. Results obtained in the second part of the study concerning 30 cases of subcarinal pathology grant a good detecting value for subcarinal mass to the inversion of the vertical gradient and the disappearance of both gradients.