title: Gadolinium-based magnetic resonance contrast agents at 7 Tesla: in vitro T1 relaxivities in human blood plasma.
abstract: PURPOSE/INTRODUCTION: The aim of this study was to determine the T1 relaxivities (r1) of 8 gadolinium (Gd)-based MR contrast agents in human blood plasma at 7 Tesla, compared with 3 Tesla.
  
  
  METHODS
  Eight commercially available Gd-based MR contrast agents were diluted in human blood plasma to concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. In vitro measurements were performed at 37 degrees C, on a 7 Tesla and on a 3 Tesla whole-body magnetic resonance imaging scanner. For the determination of T1 relaxation times, Inversion Recovery Sequences with inversion times from 0 to 3500 ms were used. The relaxivities were calculated.
  
  
  RESULTS
  The r1 relaxivities of all agents, diluted in human blood plasma at body temperature, were lower at 7 Tesla than at 3 Tesla. The values at 3 Tesla were comparable to those published earlier. Notably, in some agents, a minor negative correlation of r1 with a concentration of up to 2 mmol/L could be observed. This was most pronounced in the agents with the highest protein-binding capacity.
  
  
  CONCLUSIONS
  At 7 Tesla, the in vitro r1 relaxivities of Gd-based contrast agents in human blood plasma are lower than those at 3 Tesla. This work may serve as a basis for the application of Gd-based MR contrast agents at 7 Tesla. Further studies are required to optimize the contrast agent dose in vivo.
authors.affiliation: Department of Radiology, MR Centre- Highfield MR, Vienna, Austria. iris.noebauer@meduniwien.ac.at
authors.forename: Iris M
authors.initials: IM
authors.lastname: Noebauer-Huhmann
authors.forename: Pavol
authors.initials: P
authors.lastname: Szomolanyi
authors.forename: Vladimír
authors.initials: V
authors.lastname: Juras
authors.forename: Oliver
authors.initials: O
authors.lastname: Kraff
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D003287:Contrast Media / Q000737:chemistry / Q000493:pharmacokinetics; D005240:Feasibility Studies; D005682:Gadolinium / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D010949:Plasma / Q000737:chemistry / Q000000981:diagnostic imaging*; D011877:Radionuclide Imaging; D013223:Statistics as Topic
chemical_list: D003287:Contrast Media; D005682:Gadolinium