Reference values of physiological 18F-FET uptake: Implications for brain tumor discrimination

Area of Science:

• Neuroimaging
• Radiochemistry
• Oncology

Background:

• 18F-fluoro-ethyl-L-tyrosine positron emission tomography (18F-FET-PET) is a crucial imaging modality.
• Accurate differentiation between tumor and normal brain tissue is essential for diagnosis and treatment planning.
• Establishing reference values for 18F-FET-PET uptake in normal brain structures is necessary.

Purpose of the Study:

• To derive reference values for 18F-FET-PET uptake in normal brain and head structures.
• To enable better differentiation between tumorous and healthy tissues.
• To provide a quantitative basis for interpreting 18F-FET-PET scans.

Main Methods:

• Analysis of dynamic 18F-FET-PET data from 70 patients.
• Assessment of Maximum Standardized Uptake Value (SUVmax), Target-to-Background Ratio (TBR), and Time Activity Curve (TAC).
• Statistical comparison of uptake values in eight normal anatomic structures and tumor tissue.

Main Results:

• All analyzed normal structures showed 18F-FET uptake higher than background (TBR > 1.5).
• Venous sinuses and cranial muscles had the highest TBR (2.03±0.46), followed by gray matter structures (TBR 1.42±0.17).
• No significant differences in SUVmax, TBR, and TAC were observed between high-grade and low-grade gliomas, except for the SUVmax of the pineal gland.

Conclusions:

• Normal brain tissue exhibits increased 18F-FET uptake compared to background.
• Two distinct uptake clusters were identified: venous structures and gray matter.
• Reference uptake values aid in distinguishing normal tissues from potential pathologies on 18F-FET-PET scans.