Patent ID: 6875419

Claim:
A chemical exchange saturation transfer contrast agent comprising: a tetraazacyclododecane ligand having a general formula as follows: wherein pendent arms R, R′, R″ and R′″ are amides having a general formula: —CR 1 H—CO—NH—CH 2 —R 2 , wherein R 1 is selected from the group consisting of: H; Alkyl groups having 20 carbon atoms or less; Cycloalkyl groups having 20 carbon atoms or less; Alkyloxy groups having 20 carbon atoms or less; Alkyl ethers having 10 oxygen atoms or less and 20 carbon atoms or less; and Polyols having 20 carbon atoms or less, and R 2 is selected from the group consisting of: —COOEt; —COO − ; —POOEt; —PO 3 −2 ; pyridine; and phenol; a paramagnetic metal ion coordinated to said tetraazacyclododecane ligand wherein said paramagnetic metal is selected from the group consisting of: Eu 3+ ; Tb 3+ ; Dy 3+ ; Ho 3+ ; Pr 3+ ; Nd 3+ ; Sm 3+ ; Er 3+ ; and Tm 3+ ; and a water molecule bound to said tetraazacyclododecane ligand and said paramagnetic metal ion wherein said water molecule has a Δω·τ M ≧1 and a Δω≧6 ppm.