“…Localization of the site of the fistula can be difficult and many methods have been described (Fox 1933, Crow et al 1956, Kirchner & Proud 1960, Teng & Edalatpour 1963, Jungmann & Peyser 1963,Sinanan et al 1966.Radioactive iodinated serum albumen (RISA) cisternography is said to give good results (Di Chiro & Grove 1966, Ommaya et al 1968, Jacobson & Maran 1971, but has been superseded by indium (In l l l ) calcium OTPA injection (Hosain & Som 1972).The photon yield of RISA is low and there is a high incidence of febrile reactions. In II t is produced carrier free on the cyclotron and emits gamma radiation of 171 and 245 kev.…”