CT MEASUREMENT OF MAIN PULMONARY-ARTERY DIAMETER

The aim of this study was to determine the upper limit of the normal m ain pulmonary artery diameter using a modern CT system. This was measu red at the level of the pulmonary artery bifurcation in 100 normal sub jects using unenhanced contiguous 10 mm CT slices viewed at fixed medi astinal window settings (400/20). These normal subjects were then comp ared with similar unenhanced 10 mm images from 12 patients with proven pulmonary arterial hypertension (mean pulmonary artery pressure>20 mm Hg). The main pulmonary artery diameter in normal subjects was 2.72 cm (SD=0.3). Main pulmonary artery diameter in patients with pulmonary a rterial hypertension was significantly greater (p < 0.01) at 3.47 cm ( SD = 0.33). A pulmonary artery diameter of 3.32 cm (main pulmonary art ery diameter +2 SD) had a 58% sensitivity and 95% specificity for the presence of pulmonary arterial hypertension. It is concluded that, usi ng unenhanced axial 10 mm CT sections, the upper limit of normal main pulmonary artery diameter is 3.32 cm. Pulmonary arterial hypertension should be considered in patients with values above this level.