(Educational exhibit, RSNA 2018) V Venugopal, MD, New Delhi, India; V Mahajan, MBBS; H Mahajan, MD, MBBS TEACHING POINTS 1. Major Aortopulmonary collateral arteries are unique lesions in which the pulmonary vascular bed is multi-compartmentalized 2. Unifocalization refers to the process of changing an abnormal multi-compartment pulmonary artery circulation to a normal single compartment circulation. 3. If neither a PV or ductus is present during primary morphogenesis, the foregut source of PA persists and the native pulmonary arteries do not form normally 4. What Does the Surgeon Need to Know Before Unifocalization? - True pulmonary artery size and arborization - Number, origin, exact course, and destination of every collateral - Exact position and severity of all stenoses in both true pulmonary arteries and collaterals - For every collateral, does it intercommunicate with true pulmonary artery: “isolated supply” or “dual supply” - Relationship of collaterals to other thoracic structures: bronchial tree, pulmonary veins, esophagus - Post-stenotic pressure in collaterals TABLE OF CONTENTS/OUTLINE - Basic Physiology of MAPCA - Principles of Surgical Management - What does the surgeon want to know - Imaging protocols - Dual source CT advantages - Pitfalls and Challenges - Some case examples