Table 1. Ex vivo biodistribution of ⁶⁸Ga-DOTA-peptide in VAP-1 positive wild type mice and VAP-1 negative knockout mice bearing melanoma xenografts.

	WT 60 min	WT 60 min + KO 60 min
		Competition
Blood	1.04 ± 0.44*	0.20 ± 0.02	0.25 ± 0.01
Kidney	5.10 ± 0.86	6.39 ± 1.19	7.78 ± 1.47
Liver	1.82 ± 0.25	0.74 ± 0.08	0.97 ± 0.07
Lung	0.69 ± 0.21	0.15 ± 0.01	0.02 ± 0.00
Muscle	0.21 ± 0.07	0.03 ± 0.00	0.04 ± 0.01
Small intestine	0.59 ± 0.16	0.10 ± 0.03	0.08 ± 0.01
Tumour	0.56 ± 0.12	0.17 ± 0.02	0.20 ± 0.02

WT, VAP-1 positive wild-type mice; KO, VAP-1 negative knock-out mice. Results are expressed as standardized uptake values (mean ± SD; WT n = 3, WT + peptide competition n = 3, KO n = 2). Competition was done by injecting 500-fold molar excess of unlabeled DOTA-peptide along with ⁶⁸Ga-DOTA-peptide.

^*Note that the relatively high level of radioactivity in the blood of WT mice is due to the soluble, enzymatically active VAP-1 in serum.