Body Distribution of Ethiodol Following Lymphangiography

Abstract

Since 1955, when Kinmonth and his co-workers (8) described a practical method for the intralymphatic injection of contrast substance, lymphangiography has come into widespread use. The procedure is being employed in diagnosis, in radiotherapy, and in the study of the physiology of the lymphatic system in various diseases (1, 4, 6, 7, 9, and 11). Despite this extensive use of Ethiodol in the procedures mentioned, there has been little detailed investigation of the metabolic fate of the medium in either man or animals. This problem became of interest when the frequent radiographic appearance of oil in the lungs was noted after diagnostic procedures (2, 13). Because of this, it was concluded that the oil did not remain confined to the lymphatic system and possibly was widely distributed throughout the body. Knowledge of its distribution became of more practical significance with the advent of the therapeutic use of the medium (1, 12). It was believed that studies with radioactive tracer technics in dogs under controlled conditions would yield results which could be correlated with the experience of other investigators to provide useful information about the behavior of Ethiodol in man (3, 4, 12). Method Standard lymphangiography with I¹³¹-tagged Ethiodol was performed in 15 male beagle dogs, ranging in weight from 16 to 19 lb. The weight of the injected contrast material varied from 5.5 to 6.5 gm., with I¹³¹ concentrations of approximately 30 microcuries per gram. Seven dogs were sacrificed the third day after the injection, 3 the seventh day, 2 the tenth, and 3 the seventeenth. At autopsy, all organs and tissue masses were separated and weighed for subsequent assay of the radioactive content. The objective in tissue sampling was to obtain 3 ml. liquid samples representative in I¹³¹ concentrations of the organs from which they were drawn. Weighed samples of bulk tissue were chopped and liquefied in a food blender with known volumes of 5 normal potassium hydroxide in 95 per cent alcohol. Three milliliter aliquots of the liquefied tissue masses were prepared and counted in a well scintillation detector of standard size. Interspersed in the series of samples from organs were 4 or 5 identical sets of paired controls representative of the current activity of the Ethiodol injected. In order to learn something about the chemical form of the radioactive iodine in the various tissues at intervals after the injection, analyses were carried out to estimate relative amounts of the I¹³¹ as free iodide, and as iodine bound to lipids, protein, and amino acids. Discussion Presented in Table IA are average results of the in vivo distribution studies of the 15 dogs. As expected, the lymphatic system showed the highest concentration (percentage∕gram) of injected activity.