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Xia Y, Zeng C, Zhao Y, Zhang X, Li Z, Chen Y. Comparative evaluation of 68Ga-labelled TATEs: the impact of chelators on imaging. EJNMMI Res 2020; 10:36. [PMID: 32297029 PMCID: PMC7158967 DOI: 10.1186/s13550-020-00620-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/19/2020] [Indexed: 01/01/2023] Open
Abstract
Background 68Ga-labelled peptides targeting somatostatin receptor 2 (SSTR2) have demonstrated encouraging results in managing patients with neuroendocrine tumours (NETs). In addition to metal chelation, bifunctional chelators have also been found to impact imaging outcomes due to their differences in stability, charge, hydrophilicity, etc. In the present work, a comparative pharmacokinetic evaluation and imaging characteristics were performed between 68Ga-labelled somatostatin analogues (TATE) using NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) and DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) as bifunctional chelating agents (BFCAs). Results Both 68Ga-NOTA-TATE and 68Ga-DOTA-TATE were obtained with high radiochemical purity. 68Ga-NOTA-TATE demonstrated higher in vitro stability (≥ 99%) than 68Ga-DOTA-TATE (≥ 95%) after 3 h of incubation. The water solubilities (partition coefficients, − 1.76 ± 0.06 vs. − 2.72 ± 0.16) and plasma protein binding rates (12.12% vs. 30.6%) were lower for 68Ga-NOTA-TATE than for 68Ga-DOTA-TATE. Differential pharmacokinetics and comparable tumour affinities (within 1 h) were observed in AR42J tumour-bearing mice. Healthy volunteer imaging studies showed comparable distribution patterns of these two imaging agents. However, the maximum standardized uptake values (SUVmax) of the two tracers varied in each organ. The two PET agents demonstrated almost identical SUVmax values in the kidneys. 68Ga-NOTA-TATE did have a lower SUVmax in most other organs compared with 68Ga-DOTA-TATE, including the liver (4.2 vs. 10.1), potentially due to the lower protein binding rate. Conclusion 68Ga-NOTA-TATE and 68Ga-DOTA-TATE demonstrated comparable tumour uptake in an AR42J mouse model. An initial clinical study revealed that 68Ga-NOTA-TATE may have reduced background uptake in the major organs such as the liver. Although the subject numbers were limited, further investigation of 68Ga-NOTA-TATE is warranted for detecting SSTR2-positive neuroendocrine tumours.
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Affiliation(s)
- Yuxiao Xia
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China.,Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China
| | - Chengrun Zeng
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China.,Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China
| | - Yanhong Zhao
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China.,Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China
| | - Xinyi Zhang
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China.,Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China
| | - Zibo Li
- Biomedical Research Imaging Center, Department of Radiology, and UNC Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, 27514, USA.
| | - Yue Chen
- Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China. .,Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province, No. 25, Taiping St, Luzhou, 646000, Sichuan, People's Republic of China.
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