This title appears in the Scientific Report :
2016
Isotopic radiolabelling of the MR-contrast agent Gd-DOTA with Gd-147/149
Isotopic radiolabelling of the MR-contrast agent Gd-DOTA with Gd-147/149
Objectives Due to the new multimodal capabilities of in vivo imaging techniques, the supply of 147/149Gd appears interesting for SPECT or autoradiographic imaging with the aim to evaluate (new) MRI contrast agents. Although the production of 147/149Gd by irradiation of Sm and Eu has been published[1...
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Personal Name(s): | Buchholz, Martin (Corresponding author) |
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Brandt, Marie / Vanasschen, Christian / Spahn, Ingo / Coenen, Heinrich Hubert | |
Contributing Institute: |
Nuklearchemie; INM-5 |
Imprint: |
2015
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Conference: | 21st International Symposium on Radiopharmaceutical Sciences, Columbia (USA), 2015-05-26 - 2015-05-31 |
Document Type: |
Conference Presentation |
Research Program: |
Neuroimaging |
Publikationsportal JuSER |
Objectives Due to the new multimodal capabilities of in vivo imaging techniques, the supply of 147/149Gd appears interesting for SPECT or autoradiographic imaging with the aim to evaluate (new) MRI contrast agents. Although the production of 147/149Gd by irradiation of Sm and Eu has been published[1,2], an in vivo application of radiogadolinium has hitherto not been reported. Also the isolation of 147,149Gd from the more effective target material Eu was not described. Therefore, a bulk separation from the Eu target material was developed, followed by the authentic labeling of Gd-DOTA and a stability assessment of the complex in human blood serum (HBS). Methods A described separation of Sm2O3 and Gd2O3 with a Na-Hg amalgam[2] was systematically adapted for the new target material Eu2O3. The influence of extraction time, europium mass, amalgam mass and inert atmosphere was assessed. The resulting Eu/Gd mixture was absorbed on a DGA normal resin for the removal of excess sodium with 1 M HNO3. The lanthanides were eluted quantitatively with 0.1 M HCl, the resulting solution reduced to dryness and taken up in 0.5 ml pure water. Carrier-added and n.c.a.147/149Gd-DOTA was synthesized within 20 min at 90°C in a 0.1 M NaOAc buffer at pH 4-6 and the reaction monitored by radio-TLC. The stability of the complex in HBS was investigated at 37°C over a time period of 6 days. Results A 99.92% reduction of the Eu contamination down to 0.4 mg was achieved with the optimized Na-Hg amalgam extraction without loss of 147/149Gd. This was sufficient for first in vivo proof of principle tests with 147/149Gd-DOTA due to the strong chemical analogy of the neighboring lanthanides Gd and Eu. Removal of excess sodium was accomplished by a DGA resin enabling the application in an animal model. Carrier-added and n.c.a. 147,149Gd-DOTA were prepared with yields >99%. Additionally, over a time period of 6 days no decomposition or ion leaching was observed in HBS. Conclusions Bulk Eu was removed by amalgam extraction from c.a. as well as n.c.a 147/149Gd which was successfully used to label DOTA. This shows the possibility of an authentic labeling of (new) MRI contrast agents, allowing their in vitro or in vivo evaluation with autoradiography or SPECT. Acknowledgements The authors gratefully acknowledge the IKP-4 of FZJ for beam time and all cyclotron operators. References [1] Denzler F.-O. et al. (1997), Appl. Radiat. Isot., 48, 319. [2] Buchholz M. et al. (2014), Appl. Radiat. Isot., 91, 8 |