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Nuclear Medicine

E1122. FDG PET/CT Artifacts and Physiologic Uptake: Pearls and Pitfalls

Lawhn Heath C,  Behr S,  Flavell R,  Hernandez Pampaloni M,  Naeger D. University of California, San Francisco, San Francisco, CA

Address correspondence to C. Lawhn Heath (courtney.lawhn.heath@gmail.com)

Background Information: The purpose of FDG PET/CT is to detect pathologic findings to guide patient management. However, artifacts and physiologic uptake are common and can mask or mimic pathology. It is important for the radiologist to distinguish true pathologic findings from these artifacts and physiologic uptake to properly guide the management of the patient.

Educational Goals/Teaching Points: The aim of this exhibit is to discuss common FDG PET/CT artifacts, why they occur, and how to identify them. We highlight the patterns of physiologic uptake on FDG PET/CT that can mimic disease or interfere with an accurate interpretation and review ways to accurately recognize artifactual or physiologic FDG uptake and distinguish it from pathology.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: We first discuss common FDG PET/CT artifacts such as attenuation correction errors, motion artifact, and misregistration. Understanding why and how these artifacts occur and how to identify them is crucial to maintaining the specificity of this modality. We also discuss common pitfalls that can lead to false positives, for example, mistaking patient head motion artifact for pathologic asymmetric FDG uptake in the brain. We also discuss physiologic uptake findings on FDG PET/CT, such as brown fat, bone marrow stimulation, nonfasting examination, and altered biomechanics. We review common locations for physiologic uptake, explore the physiologic process responsible for the uptake, and discuss how to differentiate physiologic from pathologic uptake.

Conclusion: Understanding the common FDG PET/CT artifacts and physiologic findings plays an important role in patient management by maintaining high diagnostic specificity and reducing false-positives.