DDC and α estimates from the stretched exponential model are more robust to variations in b-value selection than ADC estimates, in a cohort of 42 cervical tumours

The influence of b-value selection on fitted parameters from the stretched exponential model (distributed diffusion coefficient DDC, and ‘stretching parameter’ α) and mono-exponential model (apparent diffusion coefficient ADC) was investigated in a cohort of 42 patients with cervical tumours. Diffusion-weighted images images were acquired using 9 b-values between 0 and 800smm^-2, and fitted voxel-by-voxel using all b-values (0 to 800smm^-2) and b-values n-to-800smm^-2 (where n is 20,40,60,80,100, or 300smm^-2). ADC estimates are highly sensitive to b-value selection, with reduction in ADC when low b-values are excluded, whereas DDC and α are more robust to differences in b-value selection.