CTA stands as the primary approach in diagnosing isolated PAI. The primary manifestation frequently observed was partial stenosis and occlusion of the pulmonary artery [3]. In a few cases, there were manifestations of pulmonary artery dilatation or pulmonary aneurysm [4]. It was often bilateral involvement. However, the right side was more often than the left in unilateral involvement cases [5].

The histological features of Takayasu arteritis are the presence of granulomatous inflammatory cell infiltration, destruction of smooth muscle and fibrosis in the media and adventitia. PH is a serious pulmonary circulation disease, usually with a worse prognosis. Pulmonary embolism can exhibit similar symptoms to isolated PAI at times.

Although both are manifested as pulmonary artery lumen stenosis and occlusion, pulmonary embolism involves mainly of the small-to-medium diameter pulmonary artery branches. The embolus lies in center of artery lumen, without enhancement. Isolated PAI with localized eccentric thick wall. It mostly involve from the main trunk to the branches, liking "rat tail". The wall is stiff and twisted with mild enhancement [6]. The final diagnosis is made by pathology. Glucocorticoids are the basic and effective treatment [7], and vascular surgery is also an important option for some severe cases [8].