Intramural Hematoma

Brief facts:

• Spontaneous hemorrhage caused by rupture of vasa vasorum in media
• 13% of dissections, usually no pulse deficit
• Difficult to distinguish from thrombosed AD
• Can proceed to classic dissection (16-47%)
• Long time to diagnosis: usually overlooked due to lack of non-enhanced scan
• Mortality at 1 year after dismission ~ 25%

Intramural Hematoma is a result of ruptured vasa vasorum

What the clinician needs to know

• Type A or Type B
• Regression of aortic Ø to normal in 80% of patients
• Predictors of mortality:
  - Ascending Aorta > 5 cm Ø
  - IMH thickness > 2 cm
  - Pericardial effusion (to less extend pleural effusion)
• IMH may persist or evolve into aneurysm or PAU
• Associated PAU - worse prognostic outcome

On the left a Intramural hematoma, hyperdense on a NECT. 

Classic example of IMH. Hyperdense hematoma on NECT. Intima calcifications surround the true lumen.

Same case. CECT of Intramural hematoma type B.

 Same case contrast enhanced CT.
Note that the IMH does not spiral around the true lumen, like in classic AD, helping to differentiate both.
Essentially, this is not important, therapeutical decision will be made by whether this IMH is classified as Type A or Type B IMH!
Note that there is no pericardial effusion.
IMH thickness stays below 2 cm, making regression of this Type B IMH likely (up to 80%).