Cerebral Amyloid Angiopathy (CAA)

KEY FACTS

TERMINOLOGY

• Cerebral amyloid deposition occurs in 3 morphologic

varieties

○ Common: Cerebral amyloid angiopathy (CAA)

○ Uncommon: Mass-like lesion (amyloidoma)

○ Rare: Inflammatory; diffuse (encephalopathic) white

matter involvement

IMAGING

• General findings

○ Normotensive demented patient

○ Lobar hemorrhage(s) of different ages

○ Multifocal "black dots" on T2* or SWI MR

• Protocol advice

○ Best initial screening (for acute hemorrhage) = CT

○ MR with T2* &/or SWI

TOP DIFFERENTIAL DIAGNOSES

• Multifocal "black dots" on T2/T2* MR

○ Hypertensive microhemorrhages

○ Multiple cavernous malformations (type 4)

○ Ischemic stroke with microhemorrhage

○ Diffuse axonal injury

○ Hemorrhagic metastases

○ Posterior reversible encephalopathy syndrome

CLINICAL ISSUES

• CAA: Common cause of "spontaneous" lobar hemorrhage

in elderly patients

○ Causes up to 15-20% of primary intracranial hemorrhage

(ICH) in patients > 60 years old

○ Stroke-like clinical presentation with "spontaneous" lobar

ICH

○ Chronic: Can cause vascular dementia

• CAA common in elderly patients with dementia

○ 2/3 normotensive, 1/3 hypertensive

○ 40% with subacute dementia/overt Alzheimer (overlap

common)

(Left) Axial graphic shows an

acute hematoma ﬇ with a

blood-fluid level ﬈. Multiple

microbleeds ſt and old lobar

hemorrhages ﬉ are also

typical findings in cerebral

amyloid disease. (Right) Axial

SWI MR in a 70-year-old man

with cognitive impairment and

acute visual changes shows

multiple lobar hemorrhages

﬊ and microhemorrhages ﬉

related to cerebral amyloid

angiopathy (CAA). SWI and

T2* sequences are the most

sensitive sequences for

identifying microhemorrhages

characteristic of CAA.

(Left) Axial CT in a 72-year-old

woman with no history of

hypertension shows an acute

right occipital lobe

hemorrhage ﬈. (Right) Axial

GRE MR in the same patient

shows multiple foci of

susceptibility artifact ﬈

"blooming" related to

microhemorrhages in a typical

location for CAA. CAA patients

most often present with acute

focal neurologic deficits

related to the lobar

hemorrhage. Patients also

present with cognitive

impairment related to the

microhemorrhages.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

87