Use of metal complexes as liver and gallbladder X-ray diagnostic agents

In a method of computer tomography of the liver and/or biliary tracts of a human patient, the improvement comprising:

• administering to said patient a contrast-enhancing metal complex of a metal ion of atomic number 39-42, 44-51 or 56-83 and a complexing agent, wherein said metal complex is a compound of formula III ##STR37## wherein X is, in each case independently of one another, hydrogen or a metal ion equivalent of atomic number 39-42, 44-51 or 56-83, ##STR38## stands for a C.sub.6 -ring, which can be saturated, unsaturated or aromatic, and which is substituted n-fold by group R.sup.1,
• n is 0, 1 or 2, and
• R.sup.1 is, in each case, independently of one another, hydrogen or a radical of formula IIIa ##STR39## wherein m and p are each independently 0 or 1,
• R.sup.2 is, in each case independently of one another, hydrogen or a branched or unbranched, saturated or unsaturated C.sub.1 -C.sub.6 aliphatic radical, and
• L.sup.1, L.sup.2 and L.sup.3 are each independently a direct bond, an oxygen atom, a sulfur atom, --N(H)--, --N(R.sup.2)-- or a C.sub.1 -C.sub.10 -alkylene chain, optionally interrupted by an oxygen or a sulfur atom, an --N(H)-- or an --N(R.sup.2)-- group, wherein if m and/or p is equal to zero, no two or more heteroatoms are connected directly with one another,
• wherein each free carboxyl group not involved in complexing can also be present as a salt of a physiologically compatible cation or as an amide of formula ##STR40## wherein said metal complex contains at least one radical of formula IIIa.