“…In the early 1930s iondinated oils were used for their good contrast in myelography but there were difficulties in filling nerve roots sheaths and showing any arachnoid adhesions thus these agents have in many centres been replaced with water-soluble contrast agents (Ahlgren, 1975;Danzinger, 1973;Grainger, 1971;Jensen, 1978;Junek, 1983). In the literature it appears that from the 1970's water-soluble contrast agents are preferred (Ahlgren, 1975;Danzinger, 1973;Grainger, 1971;Gensette, 1971;Jensen, 1978).…”