SYSTEMIC ARTERIAL SUPPLY TO NORMAL BASAL SEGMENTS OF LEFT LOWER LOBE - CT FINDINGS

Objective: The purpose of this study was to evaluate the usefulness of CT in making a diagnosis of systemic arterial supply to normal basal segments of the left lower lobe. Materials and Methods: We retrospecti vely reviewed chest radiography (three cases), CT (three cases), and a ngiography (two cases). Results: An anomalous systemic artery arising from the descending aorta was shown as a retrocardiac density on poste roanterior radiography and as a nodular density behind the heart on la teral radiography. Contrast enhanced CT revealed the vascular nature o f the density adjacent to the descending aorta. Dynamic CT in one pati ent demonstrated that the nodular density was composed of an anomalous systemic artery and a prominent inferior pulmonary vein. High-resolut ion CT showed the interlobar artery distal to the origin of the superi or segmental artery to be absent. The bronchial system of the left bas al segments was normal as was the pulmonary parenchyma on CT. Conclusi on: Characteristic CT findings consist of absence of the interlobar ar tery distal to the origin of the superior segmental artery and origina tion of an anomalous artery from the descending aorta that gives off b ranches to normal left basal segments. With a constellation of these C T findings, angiography would be obviated for definite diagnosis of th is anomaly.