The effect of combretastatin A4 disodium phosphate and 5,6-dimethylxanthenone-4-acetic acid on water diffusion and blood perfusion in tumours.

To evaluate the effect of the vascular disrupting drugs combretastatin A-4 disodium phosphate (CA4DP) and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) on the intra/extracellular volume fraction of water and blood perfusion in tumours using MRI.Mice with C3H mammary carcinomas underwent repeated MRI T2-weighted imaging, water-diffusion and perfusion measurements before and up to 6-hours following CA4DP and DMXAA treatment.CA4DP treatment caused an increase in water diffusion in those tumour areas that presented the lowest blood perfusion, however this appeared only after five hours. The blood perfusion in highly perfused tumour regions decreased immediately after administration of CA4DP. DMXAA treatment caused an early decrease in water diffusion in the low-perfused tumour segments and followed by a subsequent decrease in the remaining part of the tumour. The blood perfusion decreased early in all parts of the tumour.The effect of CA4DP and DMXAA on tumour blood flow was comparable. The reduction in regional blood flow caused by CA4DP in the whole tumour segment occurred early, however, changes in ADC after DMXAA appeared more extended and earlier than after CA4DP treatment, especially in tumour areas already suffering from a low blood perfusion.