For men suspected of having prostate cancer, transrectal ultrasound-guided sextant biopsy in which 12 core tissue samples are obtained randomly from the prostate has been the standard. Research during the last decade, however, has shown that multiparametric magnetic resonance (MR) imaging of the prostate with ultrasound guidance improves the accuracy of prostate cancer biopsies, which has improved detection and localization of prostate cancer and decreased detection of clinically insignificant cancer. Radiologists mark lesions that are suspicious on high-resolution images captured with multiparametric MR imaging, allowing the urologist to pinpoint the areas to biopsy. Prostate Imaging Reporting and Data Systems (PI-RADS) is a 5-point scoring system that radiologists use to determine and report if an area in the prostate is likely to be cancerous. A score of 1 indicates that the presence of clinically critical cancer is unlikely, whereas a score of 5 indicates that the presence of clinically critical cancer is likely. According to PI-RADS, diffusion-weighted imaging criteria applies to the peripheral zone and transition zone of the prostate.5 Diffusion-weighted imaging should have 2 b values when imaging the prostate. T2-weighted imaging is used for transition zone assessment of the prostate.
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