Variants of physiological FDG vascular activity on digital PET.

Area of Science:

• Nuclear Medicine
• Radiology
• Vascular Imaging

Background:

• Fluorodeoxyglucose PET/computed tomography (FDG PET/CT) is crucial for diagnosing large vessel vasculitis.
• Digital PET cameras offer enhanced spatial resolution, potentially increasing the visibility of physiological arterial wall uptake.
• Distinguishing normal variants from pathological findings is essential for accurate diagnosis.

Purpose of the Study:

• To define qualitative normal variants of arterial FDG uptake on digital PET/CT.
• To establish criteria for interpreting arterial wall activity in the context of suspected vasculitis.

Main Methods:

• Retrospective review of 126 oncological FDG PET/CT studies.
• Exclusion of patients with vasculitis, immunosuppressants, hyperglycemia, or altered FDG biodistribution.
• Visual grading of arterial wall activity (large vessels and cranial arteries) by two nuclear physicians using defined criteria.

Main Results:

• Most subjects (69%) showed grade 1 large vessel uptake; 3% had grade 2 uptake, associated with longer uptake times.
• 3% of subjects had grade 1 vertebral artery uptake.
• No cranial artery uptake was observed in temporal, maxillary, or occipital arteries.

Conclusions:

• Grade 2 large vessel uptake and grade 1 cranial artery uptake can represent normal variants on digital PET/CT.
• These variants may be linked to longer uptake times, older age, and higher glycemia.
• Findings necessitate cautious interpretation in patients evaluated for vasculitis.