Fast water-exchange Gd3+-(DO3A-like) complex functionalized with aza-15-crown-5 showing prolonged residence lifetime in vivo.

A bis-hydrated Gd3+ complex based on tris acetic acid-1,4,7,10-tetraazacyclododecane (DO3A) that was functionalized with aza-15-crown-5 demonstrated a nearly optimal water-exchanging rate (k(ex) = 3.1 x 10(7) s(-1)) and low acute cytotoxicity. Efficient magnetic resonance signal intensity enhancements and prolonged residence lifetime induced by this small molecular complex in vivo were demonstrated even with one-fifth of the standard dosage used in the clinic.