Use of small pulmonary vascular alterations to identify different types of pulmonary hypertension: a quantitative computed tomography analysis.

Background: The morphological alterations of small pulmonary vessels measured by computed tomography (CT) is increasingly used in evaluation of suspected pulmonary hypertension (PH).

Objective: To investigate the significance alterations of quantitative assessment of small pulmonary vessels on chest CT in distinguishing different types of PH and their severity.

Methods: We retrospectively analyzed a dataset of 120 healthy controls (HCs) and 91 PH patients, including 34 patients with connective tissue diseases-related PH (CTD-PH), 26 patients with idiopathic pulmonary arterial hypertension (iPAH), and 31 patients with chronic obstructive pulmonary disease-related PH (COPD-PH). The CTD-PH patients were divided into mild to moderate PH (CTD-LM-PH) group (n = 17) and severe PH (CTD-S-PH) group (n = 17). A total of 53 CTD patients without PH (CTD-nPH) were enrolled for comparison with the CTD-PH. We measured the cross-sectional area of small pulmonary vessels < 5 mm2 (%CSA <5) and between 5-10 mm2 (%CSA5-10) as a percentage of total lung area among the populations included above and compared %CSA in different types of PH groups and HCs group. The mean pulmonary arterial pressure (mPAP) was measured by right heart catheterization.

Results: The %CSA5-10 of COPD-PH, CTD-PH, and iPAH patients increased (0.21±0.09, 0.49±0.20 and 0.61±0.20, p < 0.02) sequentially, while the %CSA <5 of CTD-PH, iPAH, and COPD-PH patients decreased (0.79±0.65, 0.65±0.38 and 0.52±0.27, p < 0.05) sequentially. The %CSA5-10 was significantly higher in CTD-S-PH patients than CTD-LM-PH patients and CTD-nPH patients (0.51±0.21, 0.31±0.15 and 0.28±0.12, p < 0.01). The %CSA5-10 was positively correlated with mPAP in the CTD-PH group.

Conclusions: The quantitative parameters %CSA <5 and %CSA5-10 assessed by chest CT are useful for distinguishing different types of PH. In addition, the %CSA5-10 can provide information for identification of CTD-PH severity.