Table 4.
Summary of key differences proposed in PIRADS-v2.
| • Format and scope |
| − Intended as a “living” web-based document that will evolve with clinical practice |
| − Explicitly only for initial MRI examination, not for follow-up in active surveillance or assessment post-treatment |
| − Only proposes minimal technical parameters for an acceptable mpMRI examination, with the previous “optimal” parameters omitted |
| • MRI acquisition |
| − Spectroscopy is no longer used for PI-RADS assessment |
| − No delay in MRI post-biopsy if the primary purpose is to detect and characterise “clinically significant” cancer |
| − Anti-peristaltic medications recommended but no longer considered essential |
| − Single MRI protocol recommended, in contrast to original “detection”, “staging” and “node and bone” protocols |
| • Interpretation |
| − PI-RADS v2 score is based solely on mpMRI findings and does not take into account clinical factors |
| − Typically an overall PI-RADS score of 4 or 5 means a biopsy should be considered in this region, but the score does not explicitly state recommendations for management |
| − DWI is the dominant sequence for interpretation in the PZ, T2WI predominates for assessment of the TZ |
| − The secondary sequences are DCE in the PZ and DWI in the TZ. If the primary sequence has a PI-RADS score of 3, the secondary sequence may change the category to 4. |
| − For category 5 assessment in both the transition zone and peripheral zone, lesions must be >1.5 cm in size or demonstrate extraprostatic or invasive changes |
| − ADC maps should be consistently viewed with the same contrast windowing. Absolute ADC values should be interpreted with caution. |
| − For DCE-MRI interpretation, the presence of focal enhancement is important rather than the type of curve |
| − T2WI remains key for the purposes of staging |
| • Reporting |
| − Structured reports are recommended. Examples are yet to be provided |
| − Lesions with an overall PI-RADS score ≥3 should be reported, up to a maximum of 4 lesions, with the index lesion identified |
| − The maximal axial dimensions of a lesion should be reported using the ADC map as reference for PZ lesions and T2WI for TZ lesions |
| − Sector maps consist of 36 prostatic regions, compared to 16 (minimal) and 27 (optimal) in v1. The gland is again divided into anterior and posterior by the “17-mm line”, based on the likely reach of a 20 mm transrectal biopsy needle. |
| − The new schema incorporates the central zone and includes only alphabetic rather than alphanumeric abbreviations |
PI-RADS v2, Prostate Imaging—Reporting and Data System version 2; MRI, magnetic resonance imaging; mp, multiparametric; PZ, peripheral zone; TZ, transition zone; T2WI, T2-weighted imaging; DWI, diffusion-weighted imaging; DCE dynamic contrast-enhanced; ADC, apparent diffusion coefficient.