Fig. 1.

Applying different models to extract quantitative parameters from the mean DWI signals derived within the gross tumor volume (GTV) of a oropharyngeal cancer patient. Blue: mono-exponential model (mExp) using high and low b-values (mExp_all), orange: mExp using only high b-values $>200$ $\mathrm{s}/{\mathrm{mm}}^2$ (mExp_high), green: intra-voxel incoherent motion (IVIM) model. Fit parameters are ADC = 1293 × ${10}^{-6}{\mathrm{mm}}^2/\mathrm{s}$ (mExp_all), $\text{ADC}=1018\times {10}^{-6}{\mathrm{mm}}^2/\mathrm{s}$ (mExp_high), and $f=0.21,D=958\times {10}^{-6}{\mathrm{mm}}^2/\mathrm{s}$, $D^{\ast }=16,500\times {10}^{-6}{\mathrm{mm}}^2/\mathrm{s}$ (IVIM). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)