Multiparametric magnetic resonance imaging of the prostate: Lights and shadows.

Prostate cancer is the second most commonly diagnosed cancer in man. Since the first MRI was performed, enormous progress has been made in diagnosis, treatment, and follow up of PCa, mainly due to multiparametric prostatic MRI (mpMRI). Although mpMRI has become the best imaging tool for identifying PCa, some limitations still exist. Prostate imaging with mpMRI is, to date, the best way to locate suspicious lesions to trigger prostate biopsy, plan active surveillance, or definitive treatment. In case of relapse, mpMRI can help detect local disease and provide specific management. It is well known that there is a subset of patients in whom mpMRI fails to depict csPCa. These missed significant cancers demand great attention. Prostate mpMRI quality depends on several factors related to equipment (including equipment vendor, magnet field and gradient strength, coil set used, software and hardware levels, sequence parameter choices), patient (medications, body habitus, motion, metal implants, rectal gas), and most importantly the radiologic interpretation of images (learning curve effects, subjectivity of observations, interobserver variations, and reporting styles). Inter-reader variability represents a huge current limitation of this method. Therefore, mpMRI remains the best imaging tool available to detect PCa, guiding diagnosis, treatment, and follow up while inter-reader variability represents the best limitation. Radiomics can help identifying imaging biomarkers to help radiologist in detecting significant PCa, reducing examination times, and costs.

Rate of clinically significant prostate cancer on repeat saturation biopsy after a diagnosis of atypical small acinar proliferation.

BACKGROUND: Atypical small acinar proliferation (ASAP) occurs in approximately 5% of prostate biopsies. Approximately 30%-40% of these patients may develop prostate cancer (PCa) within a 5-year period, often not clinically significant. Current guidelines recommend a repeat biopsy within 3-6 months after the initial diagnosis, but it seem not to be the best strategy. METHODS: Objectives-evaluating the natural history of ASAP, stratifying the risk of csPCa after ASAP, identifying predictive factors of PCa after atypical diagnosis. Materials and methods-retrospective single-institutional study on patients undergoing prostate biopsy for suspicious PCa (2005-2016). We evaluated the incidence of overall PCa, intermediate-high risk of PCa and csPCa in case of ASAP, according to D'Amico classification and Epstein modified criteria. RESULTS: Out of 4.567 patients undergoing prostate biopsy, ASAP was detected in 2.6% of cases. All patients with ASAP underwent repeat saturation biopsy within 6 months and PCa was diagnosed in 34.5%. According to D'Amico classification, 26%, 5.9%, and 2.5% had low, intermediate, and high-risk disease, respectively. According modified Epstein criteria, the incidence of csPCa was 12.6%. LRT showed that the overall probability to develop PCa doubled when PSA density (PSAD) moved from values lower than 0.13 ng/ml/cc to class 0.13-0.30 ng/ml/cc, and it tripled when PSAD was higher than 0.30 ng/ml/cc. CONCLUSIONS: The rate of csPCa in patients with an initial diagnosis of ASAP who had repeat biopsy was 12.6%. The overall PCa rate was 34.5%. Among patient undergoing RP, an upgrading from ncsPCa to csPCa was reported in 35% of cases. PSAD is the only predictive factor directly associated to the risk of developing PCa on repeat biopsy. These findings suggest that immediate repeat biopsy remains the correct strategy in absence of novel predictor factors and non-invasive diagnostic evaluations.