Figure 13c. Evolution of IMH to typical dissection. (a) Unenhanced CT scan shows a crescent-shaped area of high attenuation in the descending aorta, indicating intimal displacement (arrow). (b) Contrast-enhanced CT scan acquired at the same time as a shows no enhancement of the crescent-shaped area (arrow). (c) Contrast-enhanced CT scan acquired 1 week later because the patient reported persistent pain shows aortic dilatation and dissection of the lumen (arrow).