Kirstie S. Opstad1, Simon P. Robinson2, Franklyn A. Howe1
1Division of Cardiac & Vascular Sciences, St. George's, University of London, London, United Kingdom; 2Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Sutton, United Kingdom
Vascular disrupting agents (VDAs) reduce tumour blood flow and non-invasive methods of monitoring are essential for brain tumours. Vessel size index (VSI) MRI was used to determine effects of the Tumour-VDA ASA404 (vadimezan, formerly AS1404, 5,6-dimethylxanthenone-4-acetic acid, DMXAA) on fractional blood volume (fBV) and blood vessel size (Rv) in orthotopic C6 gliomas. We show a post-treatment histogram shift towards reduced fBV and significant increase in fBV<0.4%, consistent with vascular collapse; and large post-ASA404 reductions in fBV and Rv indicate development of necrosis. In conclusion, VSI MRI appears effective in monitoring treatment effects of the Tumour-VDA ASA404 on brain tumour vasculature.