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Watanabe S, Nishijima KI, Okamoto S, Magota K, Hirata K, Toyonaga T, Shiga T, Kuge Y, Tamaki N. Biodistribution and internal radiation dosimetry of a novel probe for thymidine phosphorylase imaging, [ 123I]IIMU, in healthy volunteers. Ann Nucl Med 2020; 34:595-599. [PMID: 32361818 DOI: 10.1007/s12149-020-01469-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/21/2020] [Indexed: 11/25/2022]
Abstract
OBJECTIVE We evaluated the radiation dosage, biodistribution, human safety, and tolerability of the injection of a single dose of [123I] 5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil (IIMU), a new radiotracer targeting thymidine phosphorylase (TP), in healthy volunteers. METHODS Potential participants were tested at our hospital to confirm their eligibility. Two healthy male adults passed the screening tests. They were injected with 56 and 111 MBq of [123I]IIMU, respectively. Safety assessments were performed before and at 1, 3, 6, 9, 24, 48 h, and 1-week post-injection. Whole-body emission scans were conducted at 1, 3, 6, 24, and 48 h post-injection. Regions of interest were manually drawn to enclose the entire body at each time point, identifying high-uptake organs to obtain the time-activity curves. Urine and blood samples were collected at 1, 2, 3, 4, 5, 6, 9, 24, and 48 h post-injection. The radiation dose for each organ and the effective doses were estimated using OLINDA/EXM 1.1 software. RESULTS No adverse events were observed as of the follow-up visit > 1-week post-injection. In both subjects, the highest uptake of [123I]IIMU occurred in the liver, with peak injected activity (%IA) values of 17.7% and 15.1%, respectively. The second highest uptake was in the thyroid (0.35% and 0.66% IA). The %IA decreased gradually toward the end of the study (48 h) in all organs except the liver and thyroid. By the end of the study, 52.5% and 51.5% of the injected activity of [123I]IIMU had been excreted via the subjects' renal systems. The estimated mean effective doses of [123I]IIMU were 9.19 μSv/MBq and 10.1 μSv/MBq, respectively. CONCLUSION In this preliminary study, [123I]IIMU was safely administered to healthy adults, and its potential clinical use in TP imaging was revealed.
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Affiliation(s)
- Shiro Watanabe
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan. .,Department of Diagnostic Radiology, Hokkaido Cancer Center, 3-54, Kikusui4-2, Shiroishi-ku, Sapporo, 003-0804, Japan.
| | - Ken-Ichi Nishijima
- Central Institute of Isotope Science, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.,Advanced Clinical Research Center, Fukushima Global Medical Science Center, Fukushima Medical University, 1 Hikariga-oka, Fukushima, 960-1295, Japan
| | - Shozo Okamoto
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.,Department of Radiology, Obihiro Kosei Hospital, West 14, South 10-1, Obihiro, 080-0024, Japan
| | - Keiichi Magota
- Division of Medical Imaging and Technology, Hokkaido University Hospital, Kita-14, Nishi-5, Kita-ku, Sapporo, 060-8648, Japan
| | - Kenji Hirata
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.,Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Takuya Toyonaga
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.,PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Tohru Shiga
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Yuji Kuge
- Central Institute of Isotope Science, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan
| | - Nagara Tamaki
- Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8638, Japan.,Department of Radiology, Kyoto Prefectural University of Medicine, Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
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Higashikawa K, Horiguchi S, Tarisawa M, Shibata Y, Ohkura K, Yasui H, Takeda H, Kuge Y. Preclinical investigation of potential use of thymidine phosphorylase-targeting tracer for diagnosis of nonalcoholic steatohepatitis. Nucl Med Biol 2019; 82-83:25-32. [PMID: 31869736 DOI: 10.1016/j.nucmedbio.2019.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/05/2019] [Accepted: 12/15/2019] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Although liver biopsy is the gold standard for the diagnosis of nonalcoholic steatohepatitis (NASH), it has several problems including high invasiveness and sampling errors. Therefore, the development of alternative methods to overcome these disadvantages is strongly required. In this study, we evaluated the potential use of our tracer targeting thymidine phosphorylase (TYMP), 5-[123I]iodo-6-[(2-iminoimidazolidinyl)methyl]uracil ([123I]IIMU) for the diagnosis of NASH. METHODS The mice used as the NASH model (hereafter, NASH mice) were prepared by feeding a methionine- and choline-deficient diet for 4 weeks. A control group was similarly given a control diet. The expression levels of the TYMP gene and protein in the liver were examined by real-time reverse-transcription polymerase chain reaction and western blot analyses. The localizations of [125I]IIMU and the TYMP protein in the liver were examined by autoradiography and immunohistochemical staining, respectively. Finally, the mice were injected with [123I]IIMU and single-photon emission tomography (SPECT) imaging was conducted. RESULTS The hepatic expression levels of TYMP were significantly lower in the NASH mice than in the control mice at both mRNA and protein levels, suggesting that a decrease in TYMP level could be an indicator of NASH. [125I]IIMU was uniformly distributed in the liver of the control mice, whereas it showed a patchy distribution in that of the NASH mice. The localization of [125I]IIMU was visually consistent with that of the TYMP protein in the liver of the control and NASH mice. SPECT analysis indicated that the hepatic accumulation of [123I]IIMU in the NASH mice was significantly lower than that in the control mice [SUV (g/ml): 4.14 ± 0.87 (Control) vs 2.31 ± 0.29 (NASH)]. CONCLUSIONS [123I]IIMU may provide a noninvasive means for imaging TYMP expression in the liver and may be applicable to the diagnosis of NASH.
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Affiliation(s)
- Kei Higashikawa
- Central Institute of Isotope Science, Hokkaido University, Hokkaido 060-0815, Japan; Graduate School of Biomedical Science and Engineering, Hokkaido University, Hokkaido 060-0815, Japan.
| | - Sawako Horiguchi
- Faculty of Pharmaceutical Sciences, Hokkaido University, Hokkaido 060-0812, Japan
| | - Makoto Tarisawa
- Faculty of Pharmaceutical Sciences, Hokkaido University, Hokkaido 060-0812, Japan
| | - Yuki Shibata
- Graduate School of Biomedical Science and Engineering, Hokkaido University, Hokkaido 060-0815, Japan
| | - Kazue Ohkura
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Hokkaido 061-0293, Japan
| | - Hironobu Yasui
- Central Institute of Isotope Science, Hokkaido University, Hokkaido 060-0815, Japan; Graduate School of Biomedical Science and Engineering, Hokkaido University, Hokkaido 060-0815, Japan
| | - Hiroshi Takeda
- Faculty of Pharmaceutical Sciences, Hokkaido University, Hokkaido 060-0812, Japan
| | - Yuji Kuge
- Central Institute of Isotope Science, Hokkaido University, Hokkaido 060-0815, Japan; Graduate School of Biomedical Science and Engineering, Hokkaido University, Hokkaido 060-0815, Japan
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