The density in the aortic wall is of blood, not atherosclerosis as it was mistaken to be. The "mass" in the posterior mediastinum has the density of blood and proved to be blood, as was the right pleural effusion. Intramural hematoma weakened the aorta and progressed to rupture of the aortic wall and bleeding into the mediastinum. It may have been caused by a penetrating atherosclerotic ulcer.

The patient died within two hours after CT.

Summary: acute deterioration plus intramural hemorrhage suggest that changes in the mediastinum and the pleura are most likely to be blood.