Transition Zone Prostate Cancer: Quantitative Synthetic MR Imaging and Diffusion‐Weighted Imaging in Tumour Detection

BACKGROUND: Differentiating transition zone (TZ) prostate cancer (PCa) from benign prostatic hyperplasia (BPH) on multiparametric MRI is challenging. The comparative performance of synthetic MRI (Sy-MRI) and apparent diffusion coefficient (ADC) for this task is unclear. PURPOSE: To evaluate the utility of Sy-MRI parameters and ADC in distinguishing TZ PCa from BPH. MATERIALS AND METHODS: This retrospective study included 261 patients (89 PCa, 172 BPH) who underwent preoperative MRI (including DWI and Sy-MRI). Two independent radiologists, who did not have access to the histopathological diagnosis and clinical data, placed regions of interest (ROIs) by manually tracing the lesion margins at the largest cross-sectional area of the lesion on the ADC map to record the ADC values. On synthetic T1-mapping, T2-mapping and proton density (PD) maps, ROIs of comparable size were placed at the same level and in a corresponding location to record T1, T2 and PD values. Parameters were compared using the t-test or Mann-Whitney U test. Diagnostic performance was assessed with ROC analysis and the DeLong test. RESULTS: T1, T2 and ADC values were significantly lower in PCa than in BPH (all p ≤ 0.001), while PD showed no difference (p = 0.073). ADC yielded the highest diagnostic performance (AUC, 0.996 [95% CI: 0.992, 1]), which was significantly higher than that of T1 (AUC, 0.928 [95% CI: 0.893, 0.964]) and T2 (AUC, 0.907 [95% CI: 0.868, 0.947]) (both p < 0.001). CONCLUSION: Sy-MRI-derived T1 and T2 values can help differentiate PCa from BPH in the TZ; however, ADC remains the superior diagnostic performance within this enriched cohort of predominantly intermediate- to high-risk tumours.