TL-201 AND TC-99(M)-J001X MACROPHAGE SCINTIGRAPHY - 2 RADIONUCLIDE IMAGING TECHNIQUES FOR THE SURVEILLANCE OF ACUTE LOCALIZED RADIATION OVER-EXPOSURES

The therapeutic or surgical management of acute localized irradiation is very complicated due to the delayed occurrence of ionizing radiatio n effects. There is a great need for non-invasive imaging techniques t o delineate healthy from exposed tissues. Such a technique should beef value considering that spread of damage can occur from apparently sil ent fibrotic foci. Of the scintigraphic procedures, Tc-99(m) first-pas s scintigraphy has already been recommended by the International Atomi c Energy Agency (IAEA) for the evaluation of irradiated tissues. In or der to improve the scintigraphic surveillance of accidental over-expos ures, the potentials of Tl-201 and Tc-99(m)-J001X were evaluated on an experimental porcine model reproducing the late fibrotic effect encou ntered after localized irradiation. J001X, an acylated poly-(1,3)-gala ctoside of bacterial origin, was used for the functional imaging of th e inflammatory reaction which took place after irradiation. This scint igraphy, based on targeting of activated macrophages recruited by lesi ons, was performed together with Tl-201 scans for the assessment of bl ood perfusion and cellular metabolism. Our results demonstrate that th ese two radiopharmaceuticals provide reliable information for the mana gement of accidental localized over-exposure, J001X allowing the asses sment of the inflammatory reaction and Tl-201-chloride being mainly us eful for imaging the delayed onset of fibrosis.