18F-FAMT PET Is Useful to Distinguish between Specific Uptake and Nonspecific Uptake Compared to 18F-Flourodeoxyglucose Position Emission Tomography in Esophageal Cancer Patients.

BACKGROUND: L-[3-18F]-α-methyltyrosine (18F-FAMT) solely accumulates in tumor cells via an amino acid transport system. This selective uptake pattern results in a very high tumor-to-background ratio, enabling clear delineation of the tumor. The purpose of the present study was to assess the significance of 18F-FAMT PET, which shows little nonspecific uptake compared to 18F-flourodeoxyglucose position emission tomography (FDG PET) in esophageal cancer patients.

METHODOLOGY: PET-CT studies with 18F-FAMT and 18F-FDG were performed as part of pretreatment work-up in 82 patients with histologically confirmed esophageal cancer. We evaluated nonspecific uptakes of 18F-FDG and 18F-FAMT PET.

RESULTS: The nonspecific uptake of 18F-FAMT PET was lower than that of 18F-FDG PET (p = 0.282). In the operation group, 26.1% demonstrated nonspecific uptake in 18F-FDG PET, whereas only 2.38% (1 case) demonstrated nonspecific uptake in 18F-FAMT PET (p = 0.433). In the inoperable group, 47.5% showed nonspecific uptake in 18F-FDG PET, whereas 5.0% showed nonspecific uptake in 18F-FAMT PET (p = 0.079).

CONCLUSION: A crucial point for the diagnostic value of PET is distinguishing specific and nonspecific uptake. 18F-FAMT-PET is a very superior modality with regard to the lower rate of nonspecific uptake in esophageal cancer.