Abstract: Stable injection solutions of radiodiagnostic aids ready for use are obtained by addition to the organ- or tissue-specific carrier, before, during of after the labeling with the pertechnetate, of a compound of the formula: ##STR1## in which R denotes hydrogen, and R' denotes a sulpho- or a carboxymethyl group, or R and R' each denote a sulpho- or a carboxymethyl group, or a water-soluble salt thereof, as stabilizer. These compounds do not alter the specific organ or tissue distribution of the carrier.

Abstract: Stable injection solutions of radiodiagnostic aids ready for use are obtained by addition to the organ-or tissue-specific carrier, before, during or after the labeling with the pertechnetate, of a compound of the formula: ##STR1## in which R denotes hydrogen, and R' denotes a sulpho- or a carboxymethyl group, or R and R' each denote a sulpho- or a carboxymethyl group, or a water-soluble salt thereof, as stabilizer. These compounds do not alter the specific organ or tissue distribution of the carrier.

Abstract: A colloidal solution of human serum albumin is prepared by mixing an aqueous solution of the latter with a non-ionic surface-active agent and an acid solution of a tin(II) salt, adjusting the pH to 3.5 to 8.0 and heating at a constant temperature between 45.degree. and 100.degree. C. until complete hydrolysis of the tin(II) salt and denaturation of the albumin have taken place; the colloidal solution can also be lyophilized. By treating the solution or the lyophilizate with a .sup.99m Tc-pertechnetate solution, a colloidal preparation is obtained for scintigraphy of the reticuloendothelial system or the lymphatic system. By suitable pH adjustment, the process makes it possible selectively to obtain colloids with a particle size of, for example, 3.0-0.2 or 0.2-0.03 or below 0.03 .mu.m.