Cyclic triamine chelating agents

A method of providing an image of an internal region of a patient comprising administering to the patient a compound of the formula ##STR9## chelated with a paramagnetic metal ion wherein Z1 and Z2 each represent the atoms necessary to complete a monocyclic or polycyclic carbocyclic or heterocyclic ring system, said Z1 and Z2 independently optionally substituted with R.sup.6 and R.sup.7, respectively;

• R.sup.l, R.sup.2, R.sup.3 and R.sup.4 are independently carboxyalkyl (C.sub.1 -C.sub.2), --(CH.sub.2).sub.n --C(.dbd.O)--NH--R.sup.8, or --(CH.sub.2).sub.n --C(.dbd.O)--O--R.sup.8
• R.sup.5 is carboxyalkyl (C.sub.1 -C.sub.2);
• R.sup.6 and R.sup.7 are independently hydrogen, benzyl, or benzyloxy, said benzyl or benzyloxy optionally substituted with one, two or three substituents selected from the group consisting of amino, isocyanato (--N.dbd.C.dbd.O), isothiocyanato (--N.dbd.C.dbd.S) , --NH--C(.dbd.O)--X or --NH--C(.dbd.S)--X;
• R.sup.8 is alkyl (C.sub.1 -C.sub.20), --(CH.sub.2).sub.m --Ar, or polyhydroxyalkyl (C.sub.1 -C.sub.20);
• n is 1 or 2;
• m is 1 to 15;
• X is a targeting moiety;
• and
• Ar is phenyl optionally substituted with one, two or three substituents selected from the group consisting of amino, acylamino, hydroxy, alkyl (C1-C5) and halogen;
• and;
• scanning the patient using magnetic resonance imaging to obtain visible images of the region.