What is the role of MRI in the workup of cerebral amyloid angiopathy (CAA)?

Updated: Dec 19, 2018
  • Author: Ravi S Menon, MD; Chief Editor: Helmi L Lutsep, MD  more...
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MRI may show evidence of multiple large and small, petechial cortical and subcortical hemorrhages, even in patients without a history of previous hemorrhage. In asymptomatic patients, clinically silent microhemorrhages may serve as a marker of disease progression. [12, 13]

GRE MRI sequences show evidence of hemosiderin deposition that corresponds to old hemorrhages. In patients who present with lobar hemorrhages, evidence of old petechial bleeds can help in the diagnosis of cerebral amyloid angiopathy (CAA). [14]

On GRE sequences, punctate (usually < 5mm), round hypointensities, termed microbleeds, are frequently identified in white matter. Although these cerebral microhemorrhages are often present in amyloid angiopathy, they are not diagnostic of amyloid pathologically. Any conclusions regarding the significance of cerebral microbleeds must be interpreted given the individual patient or population being evaluated.

Microbleeds may be associated with hemorrhagic transformation of ischemic stroke. Microbleeds may be more common in patients with hypertension, but no characteristic pattern occurs in the distribution of microbleeds. Microbleeds may suggest a hemorrhage-prone angiopathy involving brain parenchyma distant from identified microbleeds.

The presence, or number, of microbleeds may impact decisions to administer thrombolytic, anticoagulant, or antiplatelet therapy.

As previously mentioned, higher number of intracranial hemorrhages (ICHs) at baseline on GRE is associated with a higher risk of future ICH, subsequent cognitive impairment, loss of independence, and death. Leptomeningeal enhancement is seen in patients with associated vasculitis.

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