Does this CT confirm pulmonary arterial enlargement?
Yes. The pulmonary trunk is significantly larger than the adjacent aorta.
This patient has primary pulmonary arterial hypertension. What do the micronodules represent?
Pulmonary capillary haemangiomatosis.
CT demonstrates micronodules that are thought to represent enlarged pre-cap arterioles and are consistent with the diagnosis of primary idiopathic pulmonary arterial hypertension or pulmonary capillary haemangiomatosis.
Note the massive right heart strain, straight / reversed septum, enlarged RV and RA and pulmonary arteries.