MIP images of SPECT/CT scans with 99mTc-J591Cdia in mice bearing subcutaneous prostate carcinoma tumours. Mice with established DU145-PSMA or control DU145 tumours received 10 to 13 μg (between 25 and 35 MBq/injection) of 99mTc-J591Cdia by tail vein injection. (a) Serial images at 5 min, 60 min, 4 h and 8 h post injection of a mouse with DU145-PSMA tumour. (b) Mouse with PSMA-negative DU145 tumour at 8 h p.i. (c) Mouse with DU145-PSMA tumour; binding of 99mTc-J591Cdia blocked with a 20 times excess of unlabelled diabody (cold competition, at 8 h p.i.). (d) Tumour uptake values in the DU145-PSMA (n = 3), DU145 (n = 3) and cold competition (comp, n = 4) groups over time as determined from SPECT/CT images (shown as mean ± SD). Arrows indicate the position of the tumour in each image. Images are scaled individually.