Anomalous systemic arterialization to normal basal segments of the left lower lobe: Helical CT and CTA findings

Purpose: The purpose of this work was to evaluate the helical CT and CT ang iography (CTA) findings of anomalous systemic artery (ASA) to the basal seg ments of the left lower lobe (LLL). Method: Three patients (two had hemoptysis, one was asymptomatic) with blot chy nodular density in the LLL revealed on chest radiographs underwent heli cal CT and CTA, Bronchoscopy was performed in two of these patients. Angiog raphy and surgery were performed in one patient. Results: All three patients demonstrated characteristic helical CT and CTA findings including 1) a sigmoid-shaped ASA originating from the lower desce nding thoracic aorta, with a distal bulbous configuration and four arterial branches supplying the basal segments of the LLL; 2) absence of an interlo bar pulmonary artery or presence of a small artery lateral to the truncus b asalis; 3) engorged vascular markings in the basal segments of the LLL; and 4) normal tracheobronchial tree and lung parenchyma. Conclusion: The findings in the present three cases suggest that the use of invasive studies such as angiography or bronchoscopy may be obviated in th e diagnosis of ASA to the LLL because diagnosis can be provided through a c lear set of criteria on helical CT and CTA.