Conventional chest radiograph is often abnormal at timepoint of diagnosis. However, the degree of PH does not correlate with the severity of radiologic abnormalities and chest radiograph is not sensitive for subtle abnormalities. It serves the detection of diffuse parenchymal lung disease or pulmonary venous hypertension due to left heart disease. Kerley B lines could also suggest veno-occlusive disease.
Enlargement of the main pulmonary artery, enlarged hilar vessels and/or decreased peripheral vessels are present in more than 90 % of patients with pulmonary hypertension . With respect to the presence of pulmonary hypertension, sensitivity and specificity of the diameter of the right pulmonary artery of 16, 17, 18, or 19 mm are 76, 68, 57 or 43 % and 67, 80, 87 or 90 %, respectively . It should be noted that 6 % of the patients enrolled in the NIH registry had a normal chest radiograph .