Perfusion studies were performed in supine position using either with full dose 148–185 MBq (4–5 mCi) of 99mTc-macroaggregated albumin (MAA) or half dose 74–93 MBq (2–2.5 mCi) for pregnant or pulmonary hypertension patients. The gene discussed is ALB; the disease is pulmonary arterial hypertension.