@article { , title = {The relationship between endogenous thymidine concentrations and [18F]FLT uptake in a range of preclinical tumour models}, abstract = {Background Recent studies have shown that 3′-deoxy-3′-[18F] fluorothymidine ([18F]FLT)) uptake depends on endogenous tumour thymidine concentration. The purpose of this study was to investigate tumour thymidine concentrations and whether they correlated with [18F]FLT uptake across a broad spectrum of murine cancer models. A modified liquid chromatography-mass spectrometry (LC-MS/MS) method was used to determine endogenous thymidine concentrations in plasma and tissues of tumour-bearing and non-tumour bearing mice and rats. Thymidine concentrations were determined in 22 tumour models, including xenografts, syngeneic and spontaneous tumours, from six research centres, and a subset was compared for [18F]FLT uptake, described by the maximum and mean tumour-to-liver uptake ratio (TTL) and SUV. Results The LC-MS/MS method used to measure thymidine in plasma and tissue was modified to improve sensitivity and reproducibility. Thymidine concentrations determined in the plasma of 7 murine strains and one rat strain were between 0.61 ± 0.12 μM and 2.04 ± 0.64 μM, while the concentrations in 22 tumour models ranged from 0.54 ± 0.17 μM to 20.65 ± 3.65 μM. TTL at 60 min after [18F]FLT injection, determined in 14 of the 22 tumour models, ranged from 1.07 ± 0.16 to 5.22 ± 0.83 for the maximum and 0.67 ± 0.17 to 2.10 ± 0.18 for the mean uptake. TTL did not correlate with tumour thymidine concentrations. Conclusions Endogenous tumour thymidine concentrations alone are not predictive of [18F]FLT uptake in murine cancer models.}, doi = {10.1186/s13550-016-0218-3}, eissn = {2191-219X}, issn = {2191-219X}, issue = {1}, journal = {EJNMMI Research}, publicationstatus = {Published}, publisher = {Springer Verlag}, url = {https://hull-repository.worktribe.com/output/972029}, volume = {6}, keyword = {Health and Health Inequalities, [18F]Fluorothymidine, Plasma, Tumour, Thymidine, Preclinical PET}, year = {2016}, author = {Heinzmann, Kathrin and Honess, Davina Jean and Lewis, David Yestin and Smith, Donna-Michelle and Cawthorne, Christopher and Keen, Heather and Heskamp, Sandra and Schelhaas, Sonja and Witney, Timothy Howard and Soloviev, Dmitry and Williams, Kaye Janine and Jacobs, Andreas Hans and Aboagye, Eric Ofori and Griffiths, John Richard and Brindle, Kevin Michael} }