Double lumens and flaps (and their mimics) on CT and MR angiography

CT and MR angiograms (CTA and MRA) often show a double lumen (circulating or non-circulating), double lumen mimics, flaps and flap-like lesions. Interpreting these radiological abnormalities is important since their causes range from benign variants to high-risk disorders. This review illustrates the radiological characteristics of a double lumen or a flap on standard CTA and MRA/MRI and discusses their causes.