Figure 11b. Type A IMH. (a) Unenhanced CT scan depicts crescent-shaped areas with high attenuation (arrows) extending along the walls of the ascending and descending aorta. The displaced intimal calcifications in the descending aorta indicate a subintimal location. A pericardial effusion (arrowheads) also is visible. (b) Contrast-enhanced CT scan shows no enhancement of attenuation in the crescent-shaped areas (arrows). IMH is less apparent here than on the unenhanced CT scan in a.