Amyloid-β
(Aβ) is ubiquitous in the central nervous system (CNS), but pathologic
accumulation of Aβ results in four distinct neurologic disorders that affect
middle-aged and elderly adults, with diverse clinical presentations ranging
from chronic debilitating dementia to acute life-threatening intracranial
hemorrhage. The characteristic imaging patterns of Aβ-related CNS diseases
reflect the pathophysiology of Aβ deposition in the CNS.
Aβ is recognized as a
key component in the neuronal damage that characterizes the pathophysiology of
Alzheimer disease, the most common form of dementia. Targeted molecular imaging
shows pathologic accumulation of Aβ and tau protein, and fluorine 18
fluorodeoxyglucose positron emission tomography and anatomic imaging allow differentiation
of typical patterns of neuronal dysfunction and loss in patients with Alzheimer
disease from those seen in patients with other types of dementia. Cerebral
amyloid angiopathy (CAA) is an important cause of cognitive impairment and
spontaneous intracerebral hemorrhage in the elderly.
Hemorrhage and white
matter injury seen at imaging reflect vascular damage caused by the
accumulation of Aβ in vessel walls. The rare forms of inflammatory angiopathy
attributed to Aβ, Aβ-related angiitis and CAA-related inflammation, cause
debilitating neurologic symptoms that improve with corticosteroid therapy.
Imaging shows marked subcortical and cortical inflammation due to perivascular
inflammation, which is incited by vascular Aβ accumulation. In the rarest of the
four disorders, cerebral amyloidoma, the macroscopic accumulation of Aβ mimics
the imaging.appearance of tumors. Knowledge of the imaging patterns and
pathophysiology is essential for accurate diagnosis of Aβ-related diseases of
the CNS.
Fuente:
Radiographics: A Review Publication of the
Radiological Society of North America, Inc 2016, 36 (4): 1147-1163.
