Multiparametric MRI in Prostate Cancer

Prostate cancer (PCa) is the second most common cancer in men and an estimated 1.1 million men worldwide were diagnosed with prostate cancer in 2012 with almost 70% of the cases occurring in more developed regions [1]. With an estimated 307.00 deaths in 2012, prostate cancer is the fifth leading cause of death from cancer in men [1]. In patients with elevated or rising prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE), random systematic transrectal ultrasound (TRUS) guided prostate biopsy is the most commonly used technique to establish PCa diagnosis. However, PSA alone has a low specificity for PCa detection [2] and several modifications that may improve the specificity of PSA in PCa diagnosis have been described such as age-specific reference ranges, free-to-total PSA ratio, PSA velocity, PSA density, PSA transition zone density, PSA molecular forms (PHI (prostate health index) score (total PSA, free PSA, and p2PSA) and the 4Kscore, which measures blood plasma levels of four different prostate-derived kallikrein proteins: total PSA, free PSA, intact PSA, and human kallikrein 2 (hK2)), and numerous other novel biomarkers (PCA3, TMPRSS2-ERG Gene fusion, etc.). Random systematic prostate sampling with TRUS guided biopsy also has its inherent limitations. First of all, clinically insignificant cancers are often identified by chance and affect survival data due to lead and length time bias from overdetection and overtreatment of indolent disease [3]. Secondly , systematic biopsies through random sampling error may lead to incorrect risk stratification and may perform poorly at documenting the exact extent and heterogeneity of the disease [4]. Lastly, undersampling, particularly, when prostate volume is taken into account, occurs in up to 30% of cases with clinically significant tumors being missed (false-negativity) on initial random systematic biopsy [5]. Efforts to overcome these sampling errors include performing multiple repeat random biopsies or increasing the core number during random or systematic template-guided transperineal saturation biopsies. However, this approach results in a marginal increase in the overall detection rate without increasing the rate of significant cancer detection [6], while increasing cost and morbidity significantly. Imaging has always been problematic in respect to PCa diagnosis and has been essentially limited to biplanar transrectal ultrasound and its modifications. Technological ultrasound developments with contrast enhancement and 3D reconfiguration have been underutilized by the uro-logical community as a whole. Isotopic efforts with FDG and 11-choline PET scans have also disappointed in terms of diagnostic yield of prostatic disease. Recently, with …