(11)C-methylaminoisobutyric acid (MeAIB) PET for evaluation of prostate cancer: compared with (18)F-fluorodeoxyglucose PET.

α-N-methyl-(11)C-methylaminoisobutyric acid ((11)C-MeAIB) is a selective substrate of system A amino acid transport, and known to accumulate in malignant lesions. The aim of this study was to evaluate the utility of MeAIB PET for the assessment of prostate cancer, compared with FDG PET.

Thirty-four men (age range 57-77 years) with prostate cancer were prospectively enrolled, and underwent MeAIB PET and FDG PET between January 2011 and January 2013. MeAIB PET and FDG PET were performed at 20 and 50 min post-injection, respectively. SUVmax of the prostate was calculated, and visual analysis was conducted for MeAIB and FDG PET studies. MRI images were visually evaluated if available. All patients received total prostatectomy subsequently, and imaging findings were compared with pathological results, including T stage, Gleason score, and tumor size. The patient-based and lesion-based sensitivity and specificity were calculated according to pathological significant cancer.

Mean value of SUVmax of (11)C-MeAIB PET and (18)F-FDG PET in prostate cancer were 3.18 (±1.90, range; 1.55-9.57) and 3.88 (±2.85, range; 2.04-14.47). MeAIB PET and FDG PET were positive by visual analysis in 47.1 % (16/34) and 44.1 % (15/34) of the patients. MRI was positive in 51.5 % (17/33). Pathological stage and Gleason score were as follows: Stage 2 (n = 23), 3 (n = 8), and 4 (n = 3); Gleason score 6 (n = 13), 7 (n = 16), 8 (n = 3), and 9 (n = 2). The sensitivities tended to be higher according to higher pathological T stage or Gleason sum score for both MeAIB and FDG PET studies. Visual analysis of both MeAIB PET and FDG PET had significant correlation with extraprostatic extension (p < 0.05). MeAIB PET and FDG PET had complementary results by visual analysis in the assessment of prostate cancer. The patient-based sensitivity of MeAIB PET, FDG PET, and MRI were 51.6, 48.4, and 56.7 %, respectively. The patient-based specificity of these modalities was 100 % for each modality.

MeAIB PET has better diagnostic results than FDG PET for the assessment of significant prostate cancer, and these PET studies showed complementary results. MRI has even better diagnostic results than (11)C-MeAIB PET. MeAIB accumulates in prostate cancer, which indicates that the system A amino acid transport pathway is activated in prostate cancer.

Annals of nuclear medicine. 2016 Jun 21 [Epub ahead of print]

Maya K Arimoto, Tatsuya Higashi, Ryuichi Nishii, Shinya Kagawa, Masaaki Takahashi, Yoshihiko Kishibe, Hiroshi Yamauchi, Satoshi Ishitoya, Hiroyuki Oonishi, Yuji Nakamoto, Kaori Togashi

Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan. ., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba, 263-8555, Japan., Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Shiga Medical Center Research Institute, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Department of Urology, Shiga Medical Center, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Department of Urology, Shiga Medical Center, 5-4-30 Moriyama, Moriyama, Shiga, 524-8524, Japan., Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto, Kyoto, 606-8507, Japan., Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Graduate School of Medicine, 54, Shogoin Kawahara-cho, Sakyo-ku, Kyoto, Kyoto, 606-8507, Japan.