Multiparametric Magnetic Resonance Imaging (MRI) (mpMRI) of the prostate consists of three parameters: high-resolution T2-weighted anatomical imaging (T2w), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE) MRI. Minimal technical requirements for the acquisition of dedicated prostate MR-images have been described in the Prostate Imaging Reporting and Data System (PI-RADS), which currently is in its version 2.1 . It also contains a standardized reporting system, which groups imaging findings on T2w, DWI, and DCE and yields a final categorization into a 5-point scale predicting the likelihood of clinically significant prostate cancer.
The diagnostic performance of mpMRI of the prostate using PI-RADS has been amply studied in numerous high-quality studies during the last decade. In 2017, a meta-analysis consisting of 21 studies, including 3857 patients, calculated a pooled sensitivity of 89% (range 73%–100%) and a pooled specificity of 73% (range 7%–100%) . The large ranges can be explained by a number of factors.
Quality criteria and subsequent certification are the fastest way to ensure this kind of high-quality reading, similar to what happened in breast cancer screening. The European Society of Urogenital Radiology conducted a Delphi survey among its members to seek consensus about this matter. Preliminary results were that image quality should be optimized through compliance to PI-RADS v2.1 and regular self and peer assessments. Reading quality should equally be compliant to PI-RADS v2.1, with a percentage of PI-RADS 3 results lower than 25% (ideally 15%) and a percentage of PI-RADS 1–2 results higher than 30%. Histopathological feedback is mandatory (e.g. through MDT participation), in order to learn from both successes and mistakes.
In conclusion, mpMRI is a great tool for prostate cancer diagnosis. It results in less (unnecessary) biopsies overall, increases the yield of clinically significant cancers and decreases the number of insignificant cancers. However, the scientific triumphs as reported in the literature do not always translate into daily practice! Urologists who hear or read about these triumphs expect the same successes in their own hospitals, but if radiologists fail to deliver that quality, they lose credibility and a great tool becomes an unreliable tool… Therefore, technical and reporting standardization of mpMRI is mandatory (as accomplished in PI-RADS v2.1), but there is also a need for training, expanding knowledge and maximizing expertise. Furthermore, quality criteria and certification will pave the way to constant reader quality and referral confidence.
The authors have no competing interests to declare.
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