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

YY 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 mm(2) (%CSA <5) and between 5-10 mm(2) (%CSA(5-10)) 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 %CSA(5-10) 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 %CSA(5-10) 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 %CSA(5-10) was positively correlated with mPAP in the CTD-PH group. CONCLUSIONS: The quantitative parameters %CSA <5 and %CSA(5-10) assessed by chest CT are useful for distinguishing different types of PH. In addition, the %CSA(5-10) can provide information for identification of CTD-PH severity.