A kit for the instant preparation of 99Tcm-citrate for tumour and inflammation scintigraphy

A lyophilized kit has been developed to produce 99Tcm-citrate (99%) instantly when mixed with 99TcmO4-. The ingredients of the kit, citrate and stannous chloride, are in a ratio of 100:1 (w/w) and are bound to 700 MBq 99Tcm, sufficient for use in a single patient. The shelf life of the kit when kept refrigerated is at least 3 months. The blood clearance and organ distribution of 99Tcm-citrate have been studied in rabbits and mice respectively, showing its fast clearance (55% at 5 min) and low uptake by the reticulo-endothelial system and other organs. The main route of clearance is via the kidneys. Scintigraphic studies in experimental mice have demonstrated high levels of accumulation of 99Tcm-citrate in turpentine-induced abscess (target-to-non-target ratio 4.2:1) and EAT implanted tumour in mice (T/NT 5:1) 1 h after its administration. In keeping with these animal studies, low uptake of 99Tcm-citrate by normal organs and fast blood clearance have been demonstrated in human patients with infection and tumour as early as 5 min post-administration. This study documents a new kit developed for the preparation of 99Tcm-citrate suitable for the scintigraphic assessment of abscess, infection and tumour.