Comparison of 2-amino-[3-¹¹C]isobutyric acid and 2-deoxy-2-[¹⁸F]fluoro-D-glucose in nude mice with xenografted tumors and acute inflammation.

OBJECTIVE: 2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) accumulates in tumors and also during active inflammation, including therapy-related inflammation. Additional PET tracers that are less avid to inflammation could be useful in differentiating cancer from inflammation and could complement the limitation of [18F]FDG-PET. 2-Amino-[3-11C]isobutyric acid ([3-11C]AIB) is a potential PET tracer for this purpose. We compared [3-11C]AIB and [18F]FDG uptakes in tumors and acute inflammation in a mouse model.

METHODS: Acute inflammatory lesions were induced in the hind legs of tumor-bearing mice by intramuscular injection of turpentine, and we conducted biodistribution and dynamic PET studies on [3-11C]AIB and [18F]FDG.

RESULTS: [3-11C]AIB tumor uptake increased with time and was statistically significantly higher than [18F]FDG uptake. In inflamed muscles, [3-11C]AIB uptake was statistically significantly lower than [18F]FDG uptake, and the tumor-to-inflammation ratio for [3-11C]AIB was statistically significantly higher than that for [18F]FDG.

CONCLUSION: [3-11C]AIB accumulates more selectively in tumor tissue than does [18F]FDG and thus has the potential of discriminating between tumors and inflammatory lesions better and of complementing the limitation of [18F]FDG.