Diagnostic value of computed high b-value whole-body diffusion-weighted imaging for primary prostate cancer

Purpose: To investigate the utility of post-acquisition computed diffusion-weighted imaging (cDWI) for primary prostate cancer (PCa) evaluation in biparametric whole-body MRI (bpWB-MRI). Methods: Patients who underwent pelvic MRI for PCa screening and subsequent bpWB-MRI for staging were included. Two radiologists assessed the diagnostic performance of the following datasets for clinically significant PCa diagnosis (grade group ≥2 according to the Prostate Imaging-Reporting and Data System, version 2.1): bpMRI₂₀₀₀ (axial DWI scans with a b-value of 2,000 s/mm² + axial T2WI scans from pre-biopsy pelvic MRI), computed bpWB-MRI₂₀₀₀ (computed WB-DWI scans with a b-value of 2,000 s/mm² + axial WB-T2WI scans), and native bpWB-MRI₁₀₀₀ (native axial WB-DWI scans with a b-value of 1,000 s/mm² + axial WB-T2WI scans). Systemic biopsy was used as reference standard. Results: Fifty-one patients with PCa were included. The areas under the curve (AUCs) of bpMRI₂₀₀₀ (0.89 for reader 1 and 0.86 for reader 2) and computed bpWB-MRI₂₀₀₀ (0.86 for reader 1 and 0.83 for reader 2) were significantly higher (p < 0.001) than those of native bpWB-MRI₁₀₀₀ (0.67 for both readers). No significant difference was observed between the AUCs of bpMRI₂₀₀₀ and computed bpWB-MRI₂₀₀₀ (p = 0.10 for reader 1 and p = 0.25 for reader 2). Conclusions: The diagnostic performance of computed bpWB-MRI₂₀₀₀ was similar to that of dedicated pelvic bpMRI₂₀₀₀ for primary PCa evaluation. cDWI can be recommended for implementation in standard WB-MRI protocols to facilitate a one-step evaluation for concurrent detection of primary and metastatic PCa.