Evaluation of the Potential of Dwi in Prostate Cancer Detection

Background: Conventional T2W imaging alone has a poor sensitivity for prostate cancer detection. This study therefore evaluated combined T2-W and diffusion weighted (DW)-MRI vs. T2-W MRI alone for identifying tumour in patients with prostate cancer. Material and Methods: 54 consecutive patients with prostate cancer (46 Stage 1 and 2, 8 stage 3) and sextant biopsies within the previous 3 months were studied. Endorectal MR images were analysed by two radiologists (1 experienced, 1 trainee) blinded to patient information and histopathology. T2W images were scored first, followed by combined T2-W and isotropic apparent diffusion coefficient (ADC) maps calculated from DW-MRI (b=0, 300, 500 and 800 s/mm). Gland apex, middle and base for each side were scored negative, indeterminate or positive for tumour. Imaging data for each sextant were compared with histology. Sensitivity, specificity and inter-observer agreement were calculated. Results: Sensitivity and specificity for tumour identification significantly improved from 50% and 79.6% (T2-W alone, experienced observer) to 73.2% and 80.8% (p<0.001). For the trainee observer there was no improvement (44.3% and 72% T2-W alone vs. 45.1% and 69.2% T2-W plus ADC maps). Inter-observer agreement was moderate for T2-W imaging alone (kappa 0.51), and fair for T2-W plus ADC maps (kappa 0.33). Conclusion: In an experienced observer, DW-MRI together with T2-W imaging can significantly improve tumour identification in prostate cancer.