- 2.PA involvement: meet at least one of three items: (1) at least one of computed tomographic pulmonary angiography (CTPA), pulmonary perfusion imaging, or pulmonary arteriography suggests thickening of vessel wall, stenosis, aneurysm, or occlusion; (2) 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) suggests high intake of local radioactive material in pulmonary artery wall; (3) pulmonary artery systolic blood pressure is higher than 50 mmHg assessed by transthoracic echocardiography (defined as PAH), without left ventricular disease.