What are the pathologic and radiologic variants of aortic dissection?

Intramural hematoma w/out intimal flap (• Acute intramural hematoma is thought to result from rupture of the vasa vasorum with hemorrhage into the wall of the aorta. • Most of these hematomas occur in the descending thoracic aorta • Acute intramural hematomas may progress to dissectiion and rupture) Penetrating Atherosclerotic Ulcer (• caused by erosion of a plaque into the aortic media， are usually localized， and are not associated with extensive propagation. • They are found primarily in the middle and distal portions of the descending thoracic aorta and are associated with extensive atherosclerotic disease. • The ulcer can erode beyond the internal elasEc lamina, leading to medial hematoma, and may progress to false aneurysm formaEon or rupture.)