Methods of diagnostic image analysis using lipophilic contrast agents

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to complexing acids and salts thereof which when combined with a paramagnetic, ferromagnetic or diamagnetic metal ion form contrast enhancing agents, wherein the acids are represented by the formula ##STR3## wherein a is 0 to 5; b is 1 to 5; each of a and b can be the same or different; each R is the same or different and is hydrogen, lower alkyl, hydroxy, halo, lower alkoxy, aryl, or lower aralkyl; at least one of R.
sub.
1, R.
sub.
2, R.
sub.
3, R.
sub.
4 or X has the formula ##STR4## wherein R.
sub.
5 is a saturated or unsaturated hydrocarbon chain having 6 to 30 carbon atoms; and the others of R.
sub.
1, R.
sub.
2, R.
sub.
3, R.
sub.
4 or X are hydrogen, hydroxyl, --COOR.
sub.
6, --CONR.
sub.
7 R.
sub.
8 or a chelating moiety wherein R.
sub.
6, R.
sub.
7, and R.
sub.
8 are the same or different and represent hydrogen, lower alkyl, lower alkoxy, lower carboxyalkylene, or a chelating moiety.
By "complexing acid" herein is meant an acid and may include a Lewis acid, which acts as a ligand for the metals of interest thereby forming a chelate.
As used herein, the term lower alkyl, when used singly or in combination, refer to alkyl groups containing one to six carbon atoms.
They may be straight chain or branched and include such groups as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl and the like.
The preferred alkyl groups contain one to four carbon atoms.
The term aryl, when used alone or in combination, refer to an aromatic ring containing six to ten ring carbon atoms.
The aryl group includes phenyl, and 1- or 2-naphthyl.
The preferred aryl group is phenyl.
The term aralkyl refers to aryl groups as described above which have alkyl groups as ring substituents.
The most preferred aralkyl group is benzyl.
As used herein, lower alkoxy refers to a lower alkyl group having at least one hydroxyl substituent.
Halo refers to the halogen compounds, especially bromine, iodine, chlorine and fluorine