Ultrasonic contrast agents, processes for their preparation and the use thereof as diagnostic and therapeutic agents

Claim 1

An ultrasonic contrast agent composed of microparticles which contains a gas and a polyaminodicarboxylic acid-co-imide derivative of the formula I, ##STR4## in which n is 1 or 2 x is 1 to 500 y is 1 to 500, where x+y is 2 to 1000, and R is O--R 1 or NH--R 2 , in which R 2 is H, (CH 2 ) m --OR 1 , (CH 2 ) m --O--C(O)--R 1 or (CH 2 ) m --O--C(O)--OR 1 , and m is 2 to 6, and R 1 is H, aryl, aralkyl, arylalkenyl, alkyl or C 3 -C 8 -cycloalkyl or a biologically inactive steroid alcohol or an amino acid, where aryl is unsubstituted or is substituted by C 1 -C 4 -alkyl, C 2 -C 4 -alkenyl, C 1 -C 4 -alkylcarbonyloxy, C 1 -C 4 -alkoxycarbonyl, C 1 -C 4 -alkoxy or hydroxyl, where the alkyl radicals specified for R 1 have 1-22 carbon atoms and the alkenyl radicals have 2-22 carbon atoms, which are not interrupted or are interrupted by a carbonyloxy or oxycarbonyl group, where the repeating units placed in square brackets are distributed randomly and/or in blocks in the polymer, and where both the repeating units labeled with x and those labeled with y are identical or different and where the amino acids are α- and/or β-linked.