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

The purpose of this work was to evaluate the helical CT and CT angiography (CTA) findings of anomalous systemic artery (ASA) to the basal segments of the left lower lobe (LLL).

Three patients (two had hemoptysis, one was asymptomatic) with blotchy nodular density in the LLL revealed on chest radiographs underwent helical CT and CTA. Bronchoscopy was performed in two of these patients. Angiography and surgery were performed in one patient.

All three patients demonstrated characteristic helical CT and CTA findings including 1) a sigmoid-shaped ASA originating from the lower descending thoracic aorta, with a distal bulbous configuration and four arterial branches supplying the basal segments of the LLL; 2) absence of an interlobar pulmonary artery or presence of a small artery lateral to the truncus basalis; 3) engorged vascular markings in the basal segments of the LLL; and 4) normal tracheobronchial tree and lung parenchyma.

The findings in the present three cases suggest that the use of invasive studies such as angiography or bronchoscopy may be obviated in the diagnosis of ASA to the LLL because diagnosis can be provided through a clear set of criteria on helical CT and CTA.