Repeatability of derived parameters from histograms following non-Gaussian diffusion modelling of diffusion-weighted imaging in a paediatric oncological cohort.

Objectives To examine repeatability of parameters derived from non-Gaussian diffusion models in data acquired in children with solid tumours.Methods Paediatric patients (30 %) over the histogram. ADC, D, DDC α , and DDC K were strongly correlated (ρ > 0.9), DDC α and α were not correlated (ρ = 0.083).Conclusion Perfusion- and kurtosis-related parameters displayed larger, more variable CV across the histogram, indicating observed clinical changes outside of D/DDC in these models should be interpreted with caution. Centiles below 5th for all parameters show high CV and are unreliable as diffusion metrics. The stretched exponential model behaved well for both DDC α and α, making it a strong candidate for modelling multiple-b-value diffusion imaging data.Key points • ADC has good repeatability as low 5th centile of the histogram distribution. • High CV was observed for all parameters at extremes of histogram. • Parameters from the stretched exponential model showed low coefficients of variation. • The median ADC, D, DDC α , and DDC K are highly correlated and repeatable. • Perfusion/kurtosis parameters showed high CV variations across their histogram distributions