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@INPROCEEDINGS{Vanasschen:825273,
      author       = {Vanasschen, Christian and Brandt, Marie and Ermert,
                      Johannes and Neumaier, Bernd and Coenen, Heinrich Hubert},
      title        = {{A}uthentically radiolabelled {M}n({II}) complexes as
                      bimodal {PET}/{MR} tracers},
      reportid     = {FZJ-2016-07744},
      year         = {2015},
      abstract     = {Objectives: Hybrid PET/MR imaging will pave the way for a
                      better understanding of physiological and disease mechanisms
                      in preclinical and clinical settings. Authentic
                      radiolabeling of MR contrast agents ensures a fast and
                      simple access to such bimodal tracers. In this case, a
                      ligand chelating a paramagnetic metal ion (e.g. Mn) spiked
                      with the authentic PET isotope (such as 52gMn) leads to a
                      labelled molecule which can be detected with both imaging
                      modalities. Paramagnetic [55Mn(CDTA)]2- shows an excellent
                      compromise between thermodynamic stability, kinetic
                      inertness and MR contrast enhancement [1]. The aim of this
                      work was a proof of principle study of
                      cyclohexanediaminetetraacetic acid (CDTA) ligands as
                      prosthetic groups for Mn-labelled PET/MR tracers.Methods:
                      N.c.a. 52gMn [t1/2: 5.6 d; Eβ+: 575.8 keV $(29.6\%)]$ was
                      produced by proton irradiation of a natCr target and
                      purified by cation-exchange chromatography [2]. CDTA
                      radiolabeling with n.c.a. 52gMn2+ was performed in NaOAc
                      buffer (1M, pH 6) at RT and monitored by radio-TLC as well
                      as IC. Purification of the complex was performed by RP-HPLC
                      and a test on stability in NaOAc buffer. A hydroxyalkyl
                      functionalized CDTA ligand was synthesized starting from
                      3-cyclohexene-1-methanol in 5 steps.Results: The
                      quantitative formation of [52gMn(CDTA)]2- was observed
                      already within 30 min at RT. The complex was stable for at
                      least 48 h at 50 °C. If an isotopic 52g/55Mn2+ mixture was
                      applied the first prototypical manganese based bimodal
                      PET/MR tracer was obtained. Furthermore, the hydroxyalkyl
                      functionalized CDTA ligand was synthesized with an overall
                      yield of $18-25\%.$ Conclusions: Due to the hydrolytic
                      stability and simple preparation of [52g/55Mn(CDTA)]2-, the
                      CDTA ligand should be highly suitable for the preparation of
                      manganese based PET/MR bimodal tracers. Acknowledgements:
                      The authors thank M. Buchholz for production of
                      52gMnCl2.References: [1] Kalman, F. et al. (2012), Inorg.
                      Chem., 51, 10065.[2] Buchholz, M. et al. (2013), Radiochim.
                      Acta, 101, 491.},
      month         = {May},
      date          = {2015-05-26},
      organization  = {21st International Symposium on
                       Radiopharmaceutical Sciences, Columbia
                       (USA), 26 May 2015 - 31 May 2015},
      subtyp        = {Plenary/Keynote},
      cin          = {INM-5},
      cid          = {I:(DE-Juel1)INM-5-20090406},
      pnm          = {573 - Neuroimaging (POF3-573)},
      pid          = {G:(DE-HGF)POF3-573},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/825273},
}