Comparisons of the tumour-to-blood (a) and tumour-to-muscle (b) uptake ratios of 18
F-SIG343 and 18
F-SIG353. Results were presented as the ratios of the radioconcentration (%ID/g) in the tumour and in the blood or muscle at 15, 30, 60 and 120 min. Data are derived from the biodistribution studies in A373 tumour-bearing mice (means ± SEM, n = 5). *P < 0.05, **P < 0.01, ***P < 0.001 treatment versus control (unpaired, two-tailed Student's t test).