LAUSR

Editor: With great interest, we read the Letters to the Editor by Dr Scialpi and colleagues (1) in the January 2018 issue of Radiology and Drs Kaji and Inamura (2) in the February 2018 issue of Radiology commenting on the article by Dr Kuhl et al in the July 2017 issue of Radiology (3) about a possible reduction in acquisition time of multiparametric magnetic resonance (MR) imaging of the prostate. In particular, Dr Kuhl and colleagues investigated the diagnostic accuracy of a shortened biparametric MR imaging protocol composed by the sole evaluation of axial T2-weighted and diffusion-weighted imaging. The authors showed how this approach led to a similar diagnostic performance in the detection of prostatic lesions compared with the standard multiparametric MR imaging protocol. In the first letter, Dr Scialpi and colleagues (1) pointed out that the elimination of sagittal and coronal T2-weighted images could make it difficult to measure both prostate and lesion volume, as well as to perform targeted biopsy when using fusion systems that require these planes. Furthermore, Dr Scialpi and colleagues suggested that the sagittal plane is essential for the assessment of extraglandular disease. On the other hand, Drs Kaji and Inamura pointed out that, in the article by Dr Kuhl and colleagues, patients were considered having a positive index test result when they had a Prostate Imaging Reporting and Data System (PI-RADS) score of 3, 4, or 5 (2–3). In this setting, considering that dynamic contrast-enhanced (DCE) evaluation allows only for an upgrade of PI-RADS score from 3 to 4 (4), it is clear that its possible contribution to a correct diagnostic assessment is not significant. Our opinion, which is consistent with data available in the literature, is that biparametric MR imaging offers clear and significant advantages over standard multiparametric MR imaging, providing a similar diagnostic accuracy but leading to a significant reduction of acquisition time, which is directly related to both patient discomfort and costs (5). Future studies are strongly warranted to better identify and evaluate all possible strategies and combination of T2-weighted imaging and diffusion-weighted imaging, considering all advantages and disadvantages of their combination. However, in the transition from PI-RADS version 1 to PI-RADS version 2, the role of MR spectroscopy and DCE imaging was already reappraised and reduced, and at the time further concerns regarding the usefulness of DCE were raised (6). In light of the recently published articles on shortened biparametric MR imaging prostatic protocols (3,5,7), our opinion is that DCE should no longer be considered mandatory and its role further revised within a new and up-to-date version of PI-RADS.