A DWI-based hypoxia model shows robustness in an external prostatectomy cohort

Prostate cancer hypoxia is a negative prognostic biomarker. A promising MRI-based tool to assess hypoxia is the 'Consumption and Supply based Hypoxia' (CSH) model based on diffusion-weighted imaging (DWI). The aim of the study was to validate the association between the CSH hypoxia fraction (HF_DWI) with pathological Grade Group (pGG) and pathological T-staging (pTstage) in an external prostatectomy cohort.

Apparent diffusion coefficient (ADC) and fractional blood volume (fBV) maps were assessed from DWI data from 291 prostatectomies and combined by the CSH model. HF_DWI was calculated for each lesion after median scaling of ADC and fBV to address differences in acquisition and analysis between centers. The absolute HF_DWI values and the associations of HF_DWI between pGG < 3 versus ≥ 3, and pTstage = 2 versus = 3 in the Netherlands Cancer Institute (NKI) cohort were compared to the obtained by original cohort (Oslo cohort). Statistical T- and Mann-Whitney tests (p<0.05) were performed. Pearson correlation was determined between HF_DWI and individual pGG groups.

The HF_DWI showed comparable absolute values and similar metric performance as in the original published cohort. Higher HF_DWI values were observed for higher pGG (Oslo: 0.27; NKI: 0.24) compared to lower pGG (Oslo: 0.11; NKI: 0.17). Similar results were obtained for pTstage. Furthermore, HF_DWI demonstrated a significant positive correlation with pGG groups 1-5 (ρ = 0.41, p<0.001).

The CSH model exhibited sufficient robustness in the external cohort, suggesting a plausible reflection of true hypoxia and enabling the use of the HF_DWI metric for further research into prostate cancer and hypoxia.