Anatomical zone and tissue type impacts the repeatability of quantitative MRI parameters and radiomic features for longitudinal monitoring of treatment response in the prostate.

[OBJECTIVE] To (1) establish the repeatability coefficient (%RC) of region of interest (ROI) and voxel-wise measurements of a comprehensive range of quantitative MRI (qMRI) parameters and radiomic features in the prostate, and (2) assess the impact of different tissue types (benign vs tumor) and anatomical zones (peripheral, PZ, and non-peripheral, nPZ) on the %RCs.

[METHODS] Test-retest qMRI was acquired in ten prostate cancer patients and six healthy volunteers. Parametric maps of apparent diffusion coefficient (ADC), diffusion coefficient (D), perfusion fraction (f), hypoxia score (HS), longitudinal relaxation time (T1), and observed transverse relaxation rate (R2*) were calculated. Fifty-nine radiomic feature maps were calculated from each of the parametric maps and T2-weighted images. The %RCs between tissue type and anatomical zones were compared using the Student's t test at 95% significance level.

[RESULTS] The %RC of ADC, D and HS, and up to 118 (out of all 413) radiomic features was significantly different between either anatomical zones, or between tumor and benign tissue, or both.

[CONCLUSIONS] DWI-derived parameters and a portion of their radiomic features require %RCs to be established specifically for anatomical zones, tumor and benign tissues. The remaining qMRI parameters and features can have a single threshold for the whole prostate.