Increased pulmonary artery diameter on chest computed tomography can predict borderline pulmonary hypertension

Abstract

Pulmonary hypertension (PH) often leads to dilatation of the pulmonary artery (PA), which can be measured on chest computed tomography (CT). While the predictive capability of PA dilatation is useful to distinguish PH (mean PA pressure ≥25 mmHg) from normal (mean PA pressure ≤ 20 mmHg), CT characteristics of borderline PH (mean PA pressure 21-24 mmHg) have not been described. We aimed to investigate whether patients with borderline PH already show PA dilatation and to assess the diagnostic accuracy of PA dilatation for borderline PH diagnosis. Between April 2003 and September 2008, consecutive symptomatic patients with a mean PA pressure below 25 mmHg on right heart catheterization who had a chest CT available were retrospectively included. PA diameters from chest CT were correlated with hemodynamic measurements and analyzed with respect to their accuracy of predicting borderline PH. Main PA diameters were significantly larger in 26 patients with borderline PH compared with 52 patients without PH (3.16 ± 0.53 vs. 2.78 ± 0.43 cm, P = 0.001). The main PA diameter on CT correlated with mean PA pressure (r = 0.496, P < 0.001) and pulmonary vascular resistance (r = 0.445, P < 0.001), and predicted borderline PH with sensitivity, specificity, negative and positive predictive values of 77%, 62%, 84%, and 50%, respectively, using a cutoff ≥2.9 cm. This first systematic investigation of CT parameters in symptomatic patients with mean PA pressures less than 25 mmHg could show that, even in patients with borderline PH, significant PA dilatation can be present, which was related to PA pressure and pulmonary vascular resistance. This can be useful for identification of patients with borderline PH for further study and to prompt further diagnostic work-up of possible underlying diseases.

Keywords: borderline pulmonary hypertension; computed tomography; early diagnosis; pulmonary artery dilatation; screening.

Figure 1

Measurement of parameters of interest on axial CT. AA: ascending aorta; LPAD: left pulmonary artery diameter; MPAD: main pulmonary artery diameter; RPAD: right pulmonary artery diameter; VB: vertebral body.

Figure 2

Selection process of patients under study. CT: computed tomography; mPAP: mean pulmonary artery pressure; RHC: right heart catheterization.

Figure 3

ROC analyses of CT parameters for the prediction of borderline PH. AA: ascending aorta; AUC: area under the curve; BSA: body surface area; CI: confidence interval; CT: computed tomography; LPAD: left pulmonary artery diameter; MPAD: main pulmonary artery diameter; RPAD: right pulmonary artery diameter; VB: vertebral body.

Figure 4

Correlation of main pulmonary artery diameter and mPAP. The dotted horizontal line indicates 20 mmHg (inclusive) as upper limit of the normal mPAP. The dotted vertical line indicates an MPAD ≥ 2.9 cm. CT: computed tomography; n: number of patients in the respective quadrant; PA: pulmonary artery; r: pearson's correlation coefficient; RHC: right heart catheterization.