It is important to understand the pathophysiology involving pulmonary arterial hypertension (PAH) and how it reflects on various structures involving the pulmonary circulation. From early grades of simple dilatation of main pulmonary trunk to severe grades, as in our study wherein the high pulmonary arterial system pressure back reflects changes in the right side of the heart are key to document in imaging. Acute or chronic pulmonary thromboembolism is one of the causes of severe PAH and has to be ruled out. In this case it turned out to be negative. 

Parenchymal lung disease (not depicted) was also absent in our patient.