Monitoring tumor response to anti-vascular therapy using non-contrast intravoxel incoherent motion diffusion-weighted MRI

Anti-vascular therapy is a promising approach to the treatment of non-small-cell lung cancer (NSCLC), where an imaging modality capable of longitudinally monitoring treatment response could provide early prediction of the outcome. In this study, we sought to investigate the feasibility of using intravoxel incoherent motion (IVIM) diffusion MRI to quantitatively assess the efficacy of the treatments of a vascular disrupting agent CA4P or its combination with bevacizumab (BV) on experimental NSCLC tumors. CA4P caused a strong but reversible effect on tumor vasculature: all perfusion-related parameters-D*, f, fD*, and Ktrans-initially showed a decrease of 30%-60% at two hours and then fully recovered to baseline on day 2 for CA4P treatment or on days 4-8 for CA4P + BV treatment; the diffusion coefficient in tumors decreased initially at two hours and then increased from day 2 to day 8. We observed a good correlation between IVIM parameters and DCE-MRI (Ktrans). We also found that the relative change in f and fD* at two hours correlated well with changes in tumor volume on day 8. In conclusion, our results suggest that IVIM is a promising alternative to DCE-MRI for the assessment of the change in tumor perfusion as a result of anti-vascular agents and can be used to predict the efficacy of anti-vascular therapies without the need for contrast media injection.

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