Simon Walker-Samuel1, Jessica K. Boult1, Lesley D. McPhail1, Simon P. Robinson1
1Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Sutton, Surrey, UK
In this study, susceptibility MRI with ultra-small paramagnetic iron oxide (USPIO) was used to estimate the vessel size index (VSI) in orthotopic PC3 prostate tumours following treatment with ZD6126, a vascular disrupting agent. It was found that orthotopic tumours exhibited larger vessels than typically found in ectopic (subcutaneous) tumour xenograft models (VSI = 6525m), and that this significantly increased following treatment with ZD6126 (post-treatment VSI = 12236m, p<0.05). An excellent correspondence was found with histological measurements of vessel size. This study highlights the potential use of VSI as a biomarker for assessing vascular architecture and response to vascular disrupting agents.