Images of Memorable Cases: Case 23 Chest radiograph of an asymptomatic 68-year-old woman whose medical history and physical examination were unremarkable. 23. Chronic aortic dissection On close inspection, the distance between a calcified plaque in this patient’s aortic arch and the outer edge of the arch was 2 cm (normal, <1 cm), suggesting dissection. Contrast-enhanced CT scan of the chest (image below) confirmed the diagnosis by demonstrating a true and false lumen separated by an intimal flap (arrow).