Fig. 1

Kinetics of ¹⁸F-FLT (top) and ¹⁸F-FDG (bottom) distribution up to 120 min after i.t infusion of 5 MBq in the primary tumor (pt) of nude mice bearing the colorectal HCT116 tumor as assessed by PET imaging. Tumors were implanted on each thigh and additionally on the right shoulder solely for animals injected with ¹⁸F-FLT. ¹⁸F-FLT uptake increased steadily in the distant contralateral (ct) and shoulder tumors (st) as it decreased in the i.t. injected tumor, in contrast to ¹⁸F-FDG that mostly diffused in the heart (he), brain (br), and kidneys (ki). Lower accumulation in healthy tissues was obtained with i.t. ¹⁸F-FLT. lu denotes the lung and li denotes the liver