Accuracy of arterial [¹⁸F]-Fluorodeoxyglucose uptake quantification: A kinetic modeling study

Area of Science:

• Nuclear medicine
• Cardiovascular imaging
• Biomedical engineering

Background:

• 2-deoxy-2-[18F]fluoro-D-glucose (FDG) PET is crucial for assessing vessel wall inflammation.
• Current guidelines recommend mean standardized uptake value (SUVmax) and target-to-blood ratio (TBRmax) for FDG signal analysis in arteries.
• These metrics lack validation against gold standards like ex vivo tissue activity or kinetic modeling-derived net uptake rate (Ki).

Purpose of the Study:

• To evaluate the accuracy of mean SUVmax and mean TBRmax in quantifying aortic wall FDG signal.
• To compare these commonly used metrics against the net uptake rate of FDG (Ki) obtained through kinetic modeling.

Main Methods:

• Dynamic PET data from 13 subjects without cardiovascular disease were analyzed.
• Ex vivo plasma activity served as the input function for voxel-by-voxel Patlak analysis (t* = 20 min) to generate Ki images.
• FDG signal in the ascending aorta was quantified using mean SUVmax and mean TBRmax according to current vascular imaging guidelines.

Main Results:

• Mean TBRmax, but not mean SUVmax, significantly correlated with aortic wall Ki (r=0.82, P<0.001).
• Similarly, mean TBRmax correlated strongly with K_i_max (r=0.83, P<0.001), while mean SUVmax did not (r=0.17, P=NS).
• Kinetic modeling (Ki) and its maximum value (Ki_max) showed strong correlation (R=0.96, P<0.0001).

Conclusions:

• Kinetic modeling validates the use of mean TBRmax as a reliable surrogate for assessing FDG net uptake rate in the arterial wall.
• These findings support the utility of TBRmax for accurate FDG signal quantification in vascular inflammation studies.
• The results have implications for PET imaging of vascular uptake, irrespective of the specific tracer's biological significance.