Abstract: The present invention relates to a contrast agent for NMR imaging constituted by a complex between a chelating agent and paramagnetic metal cations, wherein said complex corresponds to the formula I: ##STR1## or a physiologically acceptable salt of this complex, in which formula: n and n' are whole numbers from 1 to 4R.sub.1 -R.sub.7 are selected from among H, a halogen, alkyl, alkoxy, aryl, alkenyl, and cycloalkyl groups; with the alkyl groups being optionally substituted by halogen, alkoxy, alkyl, nitrile, nitro or amino; >C(R.sub.6, R.sub.7) can in addition represent >C=O;the three substituents Y are identical or different and represent H or an ionic equivalent of a divalent or trivalent paramagnetic metal cation or of a physiologically acceptable cation derived from an inorganic or organic base,with the condition that at least two of the substituents Y represent ionic equivalents of paramagnetic metal cations.

Abstract: The subject of the present invention is compounds which correspond to the following general formula: ##STR1## in which R.sub.1 and R.sub.3 independently of one another represent H, an alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or an alkylaryl group, a heterocycle, or groups which are unsubstituted or substituted, in particular by one or more hydroxyl or alkoxy groups or halogen;n represents an integer from 1 to 5;i in each case takes values from 1 to n for the n successive ##STR2## links; R.sub.2, R.sub.4.sup.i and R.sub.5.sup.i independently of one another represent H, an alkyl, alkenyl, aryl, alkoxy, hydroxyalkyl, alkoxyalkyl, amido, acyl or carboxyalkyl group, or a salt, or an alkyl ester of the latter; or R.sub.4.sup.i and R.sub.5.sup.i together form an oxo group ##STR3## R.sub.6 and R.sub.7 represent H, or R.sub.6 and R.sub.7 together form an oxo group ##STR4## x represents a 5- or 6-membered heterocycle which contains at least one nitrogen atom, or, in the event that ##STR5## where R.sub.8 and R.sub.

Abstract: The present invention relates to a process for preparing lipid microparticles of microcrystalline appearance, of a water-insoluble substance possessing an affinity for phospholipids and of at least one phospholipid, the microparticles being stable in suspension in an aqueous solution, characterized in that:a) the said substance and the said phospholipid or phospholipids are dissolved in a common organic solvent for the said substance and for the said phospholipid or phospholipids,b) the solution of said substance and of the said phospholipid or phospholipids is mixed with an aqueous solution in an amount such that an insolubilization takes place in the form of a precipitate, andc) the organic solution is removed to recover an aqueous solution containing the microparticles in the form of microsuspensions.