Signs and Artifacts in Amyloid PET

Published Online:https://doi.org/10.1148/rg.2018180160

With the advent of amyloid PET, the radiologist now plays a pivotal role in diagnosis of Alzheimer disease and therefore must have an algorithmic approach to scan interpretation as well as knowledge of the common signs and artifacts.

Establishing a diagnosis of Alzheimer dementia can be challenging, particularly early in the course of the disease. However, with disease-modifying therapies on the horizon, it is becoming increasingly important to achieve the correct diagnosis as soon as possible. In challenging presentations of dementia, such as patients with clinically atypical features or early-age onset of mild cognitive impairment, amyloid PET is a valuable tool in determining the diagnosis of Alzheimer dementia. Furthermore, preliminary data show that amyloid PET findings alter clinical management in patients who meet the appropriate use criteria. There are currently three U.S. Food and Drug Administration (FDA)–approved fluorine 18 (18F)–labeled radiopharmaceuticals that allow in vivo detection of cerebral amyloid deposition, which is a hallmark pathologic feature of Alzheimer dementia. Knowledge of the common imaging features among these three 18F-labeled radiopharmaceuticals in the normal and abnormal brain will enable the radiologist to more accurately interpret amyloid PET studies. As in other subspecialties of radiology, imaging signs in amyloid PET are helpful to distinguish if a region is normal or abnormal. This article reviews appropriate use criteria for amyloid PET, introduces the properties of the radiopharmaceuticals, explains the algorithmic approach to interpretation with examples of normal and abnormal amyloid PET scans with MRI correlation, and provides an atlas of regional amyloid PET signs and common artifacts.

©RSNA, 2018

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Article History

Received: Apr 20 2018
Revision requested: May 25 2018
Revision received: June 29 2018
Accepted: July 2 2018
Published online: Nov 13 2018
Published in print: Nov 2018