Abbreviated Biparametric MRI (RSI + T2WI) for Prostate Cancer Detection: Correlation With Histopathology

Multiparametric MRI of the prostate (mpMRI) plays an integral role in contemporary prostate cancer management. It involves the acquisition of both anatomical sequences (T1- and T2-weighted images) as well as 'functional' imaging sequences (diffusion weighted imaging (DWI) and dynamic contrast enhanced (DCE) imaging), the latter sequences being those which image water diffusivity and tissue perfusion, respectively. Advantages of mpMRI include ability to risk stratify patients prior to biopsy, enhanced detection of clinically significant cancer and reduced diagnosis of insignificant cancers, the identification of active surveillance candidates and improved local staging for subsequent surgical and radiotherapy planning. However, there are ongoing challenges encountered with prostate mpMRI in terms of patient acceptance, image acquisition technical challenges, interpretive expertise and cost.

These challenges have motivated recent investigations employing tailored MRI protocols, i.e. faster and less expensive MR exams that eliminate one or more aspects of current mpMRI technique considered redundant, while retaining the essential imaging parameters needed for equivalent diagnostic interpretation. Among these is non-contrast biparametric MRI, which involves anatomic T2 weighted images along with diffusion weighted images (DWI) as the only retained functional sequence. Both single center studies and meta analyses have demonstrated no added value for DCE compared to the combination of T2WI and DWI, Overall cancer detection rates have been found to be equivalent for bpMRI compared to mpMRI, independent of reader experience, with comparable efficacy to guide cognitive targeted, MRI-targeted and MRI-US fusion guided biopsy. Equivalence between bpMRI and mpMRI for cancer detection has also been corroborated in two recently published meta analyses. Based upon our institution's experience with prostate mpMRI, avoidance of gadolinium and DCE imaging would be associated with a 30 percent reduction in scan cost and 40 percent reduction in total time (i.e. scan time plus patient preparatory time).