Acute spontaneous aortic pathologies associated with intramural hematoma: can a differential diagnosis be made by imaging techniques?

Acute intramural aortic hematoma may result from ruptured vasa vasorum without intimal disruption (IMH hereafter) but can also be found in association with processes in which an intimal lesion is present, such as aortic dissections (AD), where the hematoma represents the acute thrombosis of the false lumen, or in penetrating atherosclerotic ulcers (PAU), where blood collects beyond the disrupted internal elastic lamina. As the clinical presentation of these conditions is very similar, imaging techniques should aim both to diagnose the hematoma and to characterize the underlying pathology. This review critically analyzes the diagnostic potential of several imaging methods based on personal experience and literature reports. Although intramural hematoma can be easily diagnosed unrespective of the tomographic imaging modality, it is usually difficult to distinguish between IMH and hematomas associated either to AD or to PAU. Indeed, only PAU related hematomas can be consistently diagnosed due to the high probability of unveiling the causative wall ulceration; conversely, the differential diagnosis between IMH and AD - associated hematomas is still matter of controversy. According to the literature, the two conditions cannot be differentiated by transesophageal echocardiography, though some reports state that a distinction might be made by MR imaging. As regards CT, only a small percentage of AD - associated hematomas exhibit clear evidence of a typical intimal flap, allowing for a safe diagnosis to be made: often, unfortunately, the intimal lesion subsequently found at surgery cannot be detected, yielding a picture of IMH. Therefore, the radiological report should give the same diagnostic probability to both conditions.