Author/Authors :
Nishii, Ryuichi Department of Molecular Imaging and Theranostics - National Institute of Radiological Sciences (NIRS) - Inage-ku - Chiba, Japan , Higashi, Tatsuya Department of Molecular Imaging and Theranostics - National Institute of Radiological Sciences (NIRS) - Inage-ku - Chiba, Japan , Kagawa, Shinya Shiga Medical Center Research Institute - Moriyama - Moriyama - Shiga, Japan , Arimoto, Maya Department of Diagnostic Imaging and Nuclear Medicine - Graduate School of Medicine - Kyoto University - Shogoin Kawahara-cho - Sakyo-ku - Kyoto, Japan , Kishibe, Yoshihiko Shiga Medical Center Research Institute - Moriyama - Moriyama - Shiga, Japan , Takahashi, Masaaki Shiga Medical Center Research Institute - Moriyama - Moriyama - Shiga, Japan , Yamada, Shigeki Department of Neurosurgery - Rakuwakai Otowa Hospital - Otowachinjicho - Yamashina-ku - Kyoto, Japan , Saiki, Masaaki Department of Radiology - Japanese Red Cross Otsu Hospital - Otsu - Shiga, Japan , Arakawa, Yoshiki Department of Neurosurgery - Graduate School of Medicine - Kyoto University - ShogoinKawahara-cho - Sakyo-ku - Kyoto, Japan , Yamauchi, Hiroshi Shiga Medical Center Research Institute - Moriyama - Moriyama - Shiga, Japan , Okuyama, Chio Shiga Medical Center Research Institute - Moriyama - Moriyama - Shiga, Japan , Hojo, Masato Department of Neurosurgery - Shiga Medical Center - Moriyama - Moriyama - Shiga, Japan , Munemitsu, Toshihiro Department of Neurosurgery - Shiga Medical Center - Moriyama - Moriyama - Shiga, Japan , Sawada, Masahiro Department of Neurosurgery - Shiga Medical Center - Moriyama - Moriyama - Shiga, Japan , Kobayashi, Masato Kanazawa University - Kodatsuno - Kanazawa - Ishikawa, Japan , Kawai, Keiichi Kanazawa University - Kodatsuno - Kanazawa - Ishikawa, Japan , Nagamachi, Shigeki Department of Radiology - Faculty of Medicine - University of Miyazaki - Kihara Kiyotake-cho - Miyazaki, Japan , Hirai, Toshinori Department of Radiology - Faculty of Medicine - University of Miyazaki - Kihara Kiyotake-cho - Miyazaki, Japan , Miyamoto, Susumu Department of Neurosurgery - Graduate School of Medicine - Kyoto University - ShogoinKawahara-cho - Sakyo-ku - Kyoto, Japan
Abstract :
[N-methyl-C-11]α-Methylaminoisobutyric acid (MeAIB) is an artificial amino acid radiotracer used for PET study,
which is metabolically stable in vivo. In addition, MeAIB is transported by system A neutral amino acid transport, which is
observed ubiquitously in all types of mammalian cells. It has already been shown that MeAIB-PET is useful for malignant
lymphoma, head and neck cancers, and lung tumors. However, there have been no reports evaluating the usefulness of MeAIBPET in the diagnosis of brain tumors. e purpose of this study is to investigate the ecacy of system A amino acid transport PET
imaging, MeAIB-PET, in clinical brain tumor diagnosis compared to [S-methyl-C-11]-L-methionine (MET)-PET. Methods.
irty-one consecutive patients (male: 16, female: 15), who were suspected of having brain tumors, received both MeAIB-PETand
MET-PET within a 2-week interval. All patients were classified into two groups: Group A as a benign group, which included
patients who were diagnosed as low-grade astrocytoma, grade II or less, or other low-grade astrocytoma (n = 12) and Group B as
a malignant group, which included patients who were diagnosed as anaplastic astrocytoma, glioblastoma multiforme (GBM), or
recurrent GBM despite prior surgery or chemoradiotherapy (n = 19). PET imaging was performed 20 min after the IV injection of
MeAIB and MET, respectively. Semiquantitative analyses of MeAIB and MET uptake using SUVmax and tumor-to-contralateral normal brain tissue (T/N) ratio were evaluated to compare these PETimages. ROC analyses for the diagnostic accuracy of MeAIBPET and MET-PET were also calculated. Results. In MeAIB-PET imaging, the SUVmax was 1.20 ± 1.29 for the benign group and
2.94 ± 1.22 for the malignant group (p < 0.005), and the T/N ratio was 3.77 ± 2.39 for the benign group and 16.83 ± 2.39 for the
malignant group (p < 0.001). In MET-PET, the SUVmax was 3.01 ± 0.94 for the benign group and 4.72 ± 1.61 for the malignant
group (p < 0.005), and the T/N ratio was 2.64 ± 1.40 for the benign group and 3.21 ± 1.14 for the malignant group (n.s.). For the
analysis using the T/N ratio, there was a significant difference between the benign and malignant groups with MeAIB-PET with
p < 0.001. -e result of ROC analysis using the T/N ratio indicated a better diagnosis accuracy for MeAIB-PET for brain tumors
than MET-PET (p < 0.01). Conclusions. MeAIB, a system A amino acid transport-specific radiolabeled agents, could provide
better assessments for detecting malignant type brain tumors. In a differential diagnosis between low-grade and high-grade
astrocytoma, MeAIB-PET is a useful diagnostic imaging tool, especially in evaluations using the T/N ratio. Clinical trial registration. -is trial was registered with UMIN000032498.
