Intramural hematoma is an atypical form of aortic dissection due to haemorrhage into the wall from the vasa vasorum without an intimal tear. Non-contrast CT shows a cuff of high attenuation around the aortic lumen in the acute phase that is low attenuation on post-contrast CT. Intimal calcification may be displaced inwards. Echocardiography and MRI may also detect the abnormality but conventional angiography will not. The two main differential diagnoses are a thrombosed false lumen in classic aortic dissection, and aortitis.
Reference: Sebastia C. et al Aortic dissection: diagnosis and follow-up with helical CT, Radiographics 1999;19:45-60

Credit: Dr Donna D’Souza