1. INTRODUCTION
An important biomarker for predicting and diagnosing hypertension is the modified main pulmonary arteries(PA), which is typically found in patients with pulmonary hypertension (PH) and has a diameter that is significantly bigger than that of a normal person. A broadening of the PA in chronic obstructive pulmonary disease (COPD) is linked to higher exacerbation risk and lower survival rates. Blockage of one of the pulmonary arteries, mostly caused by blood clots, causes Pulmonary Embolism (PE). Therefore the early diagnosis of these pulmonary diseases, assessing the risk, and planning treatment for the patients at the early stage is required. Recently, advances in cardiac imaging have been accepted as good tools to help clinicians with early diagnosis and advanced planning in surgery. For the evaluation of many Pulmonary Vascular Diseases(PVD), the morphological examination of the Pulmonary Artery (PA) is crucial. However, even for specialists, the diagnosis procedure frequently takes a long time due to the enormous size and complexity of various imaging modalities; the pulmonary arteries must therefore be correctly and effectively segmented out. Angiography offers insights into the blood flow and conditions of the vascular tree. Three-dimensional volumetric angiography information can be obtained using magnetic resonance (MRA), ultrasound, or x-ray-based technologies like computed tomography (CT). Currently, it is standard procedure to evaluate coronary and pulmonary artery diseases with computed tomography angiography (CTA) as it provides high-resolution 3D imaging as non-invasiveness. Various undermentioned reasons account for the difficulty of the pulmonary artery segmentation: