Specific Imaging Findings

Cerebral amyloid angiopathy (CAA) typically presents in patients over 60 years of age with hemorrhages that are characteristically superficial, large, and lobar. They usually involve the cortex and subjacent white matter of the frontal and parietal lobes, with relatively minimal associated mass effect. The hemorrhage often extends to the subarachnoid and subdural spaces. Multiple hemorrhages of different ages and even multiple simultaneous bleeds may be seen. The blood products within the hematoma tend to sediment posteriorly, frequently giving the appearance of fluid levels. All these acute findings are well seen on CT images. The other characteristic feature of CAA are punctuate cortico-subcortical hypointensities on T2*-weighted images that correspond to chronic microhemorrhages. The sensitivity for microbleeds can be further increased with thin sections and susceptibility-weighted imaging (SWI). Superficial siderosis also occurs with high prevalence, and CAA is one of the most common causes of non-traumatic cortical subarachnoid hemorrhage. MRI is best suited for identification of small or chronic hemorrhages, exclusion of other causes, and assessment of disease progression.

Pertinent Clinical Information

CAA is probably the most common cause of spontaneous intracerebral hemorrhage after 70 years of age, and may be responsible for up to 10% of all nontraumatic intraparenchymal hemorrhages, with female predominance. There is a propensity for multiple and recurrent hemorrhages, and mortality is relatively low. However, many cases of CAA are asymptomatic. The diagnosis is established according to Boston criteria, with probable CAA defined as multiple T2*WI microbleeds restricted to lobar cortico-subcortical regions in patients≥ 55 years old.