Potential False-Positive FDG PET Imaging Caused by Subcutaneous Radiotracer Infiltration

Abstract

Whole-body fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning has been useful in the management of a variety of malignancies with high accuracy. However, numerous nonmalignant lesions can also result in increased FDG accumulation and consequently may cause potential false-positive interpretation if the causes are not recognized. A single focus of FDG accumulation in the axilla can often easily be attributed to tracer infiltration when the injection was on the same side. However, multiple foci of FDG uptake can be similar to malignant lesions. A case is presented in which the follow-up study clarified the nature of multifocal increased FDG uptake in the axilla.

Focal lung uptake of 18F-fluorodeoxyglucose (18F-FDG) without computed tomography findings

“…The absence of positive lymph nodes along the drainage route of the site of paravenous injection further supports the hypothesis that the radiotracer reached the lung through the bloodstream [9].…”

The use of positron emission tomography in detecting hepatoblastoma recurrence—a cautionary tale

“…[18][19][20] We postulate that the reasons for the false-positive results in our series may be a very high degree of sensitivity in detection of increased metabolic activity using PET. Second, because the liver has regenerative capacity, hyperplasia of hepatocytes at the resection margin may also mimic tumor recurrence.…”

A false-positive finding in therapeutic evaluation: hypermetabolic axillary lymph node in a lymphoma patient following FDG extravasation

“…The case report we describe here is an example of a complex scan where discordant findings are to be interpreted in the context of an overall decrease or disappearance of previous FDG uptake sites and where the appearance of an FDG avid lymph node is situated next to an area of radiotracer extravasation. FDG accumulation within the axilla following subcutaneous radiotracer infiltration has been described before with FDG [8] and with bone tracer MDP [9].…”