Cover Picture: When are Two Waters Worse Than One? Doubling the Hydration Number of a Gd–DTPA Derivative Decreases Relaxivity (Chem. Eur. J. 20/2005)

✍ Scribed by Peter Caravan; John C. Amedio Jr.; Stephen U. Dunham; Matthew T. Greenfield; Normand J. Cloutier; Sarah A. McDermid; Marga Spiller; Stephan G. Zech; Richard J. Looby; Arnold M. Raitsimring; Thomas J. McMurry; Randall B. Lauffer

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 151 KB
• Volume: 11
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200590063

✦ Synopsis

MRI contrast agents act by relaxing water protons. When an acetate group on the MRI angiography contrast agent MS‐325 is replaced with a methyl group, it opens up a coordination site for a second water ligand. The additional water is expected to improve the relaxivity of the new complex, and this is observed in buffer solution. However, in the presence of the plasma protein serum albumin the relaxivity is only about half that of MS‐325, making the new compound less attractive for blood vessel imaging. On page 5866 ff., P. Caravan et al. describe the synthesis of this novel gadolinium complex and report mechanistic studies indicating that slow water exchange limits relaxivity. The artwork was created by Vincent Jacques.