Quantitative brain [¹⁸F]FDG PET beyond normal blood glucose levels

Area of Science:

• Neuroscience
• Nuclear Medicine
• Preclinical Imaging

Background:

• Standardized Uptake Value (SUV) from static [¹⁸F]FDG PET is crucial in preclinical research for assessing brain glucose metabolism.
• SUV measurements are sensitive to variations in blood glucose levels (BGL), complicating interpretation and reproducibility.
• Kinetic modeling, while accurate, requires complex dynamic PET acquisitions, making SUV a simpler alternative.

Purpose of the Study:

• To develop and validate a novel model for standardizing [¹⁸F]FDG SUV measurements across a wide range of BGL.
• To investigate the feasibility of SUV-based approaches for preclinical brain imaging under diverse glycemic conditions.
• To establish reproducible SUV measurements independent of pre-scan BGL variations.

Main Methods:

• Performed dynamic and static brain [¹⁸F]FDG PET scans in 52 rats with controlled BGL (hypoglycemia, hyperglycemia, normoglycemia).
• Calculated whole-brain and regional SUV from co-registered PET images.
• Estimated Cerebral Metabolic Rate of Glucose (CMRglc) using 2-Tissue Compartment Model (2TCM) and Patlak plot for validation.

Main Results:

• Established normoglycemia reference value at BGL = 100±6 mg/dL.
• Developed a 2nd-degree polynomial model (C1=0.66E-4, C2=-0.0408, C3=7.298) correlating SUV and BGL (10-338 mg/dL) using pre-injection BGL.
• Corrected SUV estimations showed high correlation with CMRglc (R²=0.54 for 2TCM, R²=0.49 for Patlak), validating the model's accuracy.

Conclusions:

• A robust, non-linear model was established to standardize [¹⁸F]FDG SUV measurements based on pre-scan BGL.
• The model effectively generates SUV-based surrogates of CMRglc across a broad spectrum of BGL.
• This approach offers potential for adoption as a standard protocol in preclinical brain [¹⁸F]FDG PET imaging.