Pre-trial quality assurance of diffusion-weighted MRI for radiomic analysis and the role of harmonisation

•Mean ADC values are robust across different scanners with imaging protocol standardisation.•Radiomic features of ADC map in a homogeneous phantom show substantial variation between MRI systems, even after ComBat harmonisation.•Resampling to a smaller voxel size provides more repeatable and reproducible radiomic features than resampling to a larger voxel size. The aim of this study was to perform a quantitative quality assurance of diffusion-weighted MRI to assess the variability of the mean apparent diffusion coefficient (ADC) and other radiomic features across the scanners involved in the REGINA trial. The NIST/QIBA diffusion phantom was acquired on six 3 T scanners from five centres with a rectum-specific diffusion protocol. All sequences were repeated in each scan session without moving the phantom from the table. Linear interpolation to two isotropic voxel spacing (0.9 and 4 mm) was performed as well as the ComBat feature harmonisation method between scanners. The absolute accuracy error was evaluated for the mean ADC. Repeatability and reproducibility within-subject coefficients of variation (wCV) were computed for 142 radiomic features. For the mean ADC, accuracy error ranged between 0.1 % and 8.5 %, repeatability was