RT Journal Article SR Electronic T1 Difference of transport efflux in the rat C6 gliomas: comparative PET study between L and D-isomer of 11C-Methionine. JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1278 OP 1278 VO 59 IS supplement 1 A1 Naoki Tani A1 Tadashi Watabe A1 Nobuto Hirai A1 Tatsuya Sakai A1 Yuwei Liu A1 Sadahiro Naka A1 Yasukazu Kanai A1 Mitsuaki Tatsumi A1 Eku Shimosegawa A1 Jun Hatazawa YR 2018 UL http://jnm.snmjournals.org/content/59/supplement_1/1278.abstract AB 1278Purpose: 11C-Methionine is a major amino acid PET tracer and L-isomer is usually used for the PET examinations. Previous study reported that D-isomer of 11C-Methionine (D-11C-Met) showed lower uptakes in the liver, but higher uptakes in the tumor compared to L-11C-Methionine (L-11C-Met) in the rats. The purpose of this study was to evaluate the usefulness of D-11C-Met as a tumor-detection probe and to compare the results with our previous study on L-11C-Met. [Methods] The rat tumor xenograft models (male F344 rat) were established by subcutaneous injection of glioma cells and the rat inflammation models (male Wistar rat) by subcutaneous injection of turpentine oil. The rat tumor xenograft models (n=6, weight = 184 ± 13.5g, 8 weeks old) and the rat inflammation models (n=6, weight = 212 ± 6.3g, 8 weeks old) were administered D-11C-Met (43.7 ± 9.28 MBq) via tail vein under 2% isoflurane anesthesia. 30min dynamic PET scans (n=4) and 10min static PET scans (n=8, 20min after administration) were performed. We analyzed the PET/CT images by Pmod (Ver 3.6) and placed volumes of interest (VOIs) over the tumors and inflammatory lesions. The accumulation of D-11C-Met was evaluated by standardized uptake value (SUV) and compared the uptakes between the tumors and the inflammatory lesions and to the previous study of L-11C-Met by unpaired t-test. After the PET scans, tumor tissues and inflammatory lesions were resected for histological analyses. [Results] Time activity curves showed that uptakes of D-11C-Met in the tumors was significantly higher than those in the inflammatory lesions (p<0.01). Static PET analysis based on SUVmax showed the accumulation of D-11C-Met was significantly higher in the tumors than in inflammations (SUVmax = 2.33 ± 0.26, 1.58 ± 0.18, respectively, p<0.01). In comparison with our previous study using L-11C-Met, the peak uptake of the both probes showed no significant differences (3min after administration), but the accumulation of D-11C-Met in the tumors was significantly lower than that of L-11C-Met in tumors from 11min after administration (p<0.01). In the static PET analysis, D-11C-Met showed significantly lower accumulation in the tumor than L-11C-Met did. (SUVmax = 2.16 ± 0.30, 3.39 ± 0.43, respectively). On the other hand, time activity curves and static PET scans of the inflammations showed there was no significant difference between D-11C-Met and L-11C-Met. In histological analysis, in inflammatory lesions, infiltrating macrophages and granulocytes and granulation and fibrous tissues that surrounded these cells were observed in inflammatory lesions. In tumor sections, irregular cell proliferation was observed. [Conclusion] D-11C-Met showed high accumulation in the tumor and low accumulation in the inflammatory lesion. However, in comparison with L-11C-Met, D-11C-Met was washed out faster from the tumor, suggesting low utility of D-isomer in the metabolic pathway to the protein synthesis. It was indicated that D-11C-Met was inferior to L-11C-Met as tumor-detection probe possibly due to the faster efflux via amino acid transporter from the intracellular pool.