A Phase 0 Study for Amino Acid Imaging Using _D-¹⁸F-FMT PET in Human Brains

Aim: The aim of the present phase 0 study was to obtain information about distribution, toxicity, pharmacokinetics, and optimal scan time of _D-¹⁸F-FMT (FMT), a new amino acid PET tracer. Materials and

Methods: Six control subjects (median age = 21 y) and 7 patients (median age = 66 y) with primary (n = 3) or metastatic brain tumor (n = 4) were enrolled (M: F = 6: 7). We acquired 5 times of whole-body PET images during 4 hours (4 control subjects) after injection of 370 MBq of FMT or a 60 min dynamic brain PET image (2 control subjects and 7 patients). The distribution of FMT in each organ was assessed on whole-body PET dataset and the ratios of brain tumor to normal cerebral uptake (TN ratio) were calculated on each PET dataset.Results: The estimated whole-body radiation dose was 13.2 µSv/MBq and the highest uptake was observed in the kidney and urinary bladder. No adverse event was observed. In normal brain, FMT cerebral uptake decreased to 5 min after injection, but gradually increased from 10 min to 60 min. Ten min after the FMT injection, the TN ratios of 7 patients was highest at 5.30 ± 1.51, and then gradually decreased. The TN ratio was higher than 4 from 3 min to 30 min after the FMT injection, while the mean TN ratio was 3.41 ± 0.74 between 30 min and 60 min after the FMT injection.Conclusion: FMT is safe and its kinetic behavior is suitable for amino acid imaging in the brain. The PET images within 30 min after the FMT injection are more favorable for the imaging of the brain tumor because the TN ratio is higher than the PET images after 30 min.