What is PI-RADS v2.1 and who publishes it?

PI-RADS (Prostate Imaging Reporting and Data System) v2.1 is a standardized prostate MRI scoring system published by the American College of Radiology (ACR) and the European Society of Urogenital Radiology (ESUR). Scores range from 1 (very low suspicion for clinically significant cancer) to 5 (very high suspicion). The system was updated from v2 to v2.1 in 2019 to refine transition zone scoring rules and clarify the role of DCE.

What is the dominant sequence for peripheral zone versus transition zone lesions?

For peripheral zone lesions, DWI/ADC is the dominant sequence. For transition zone and anterior lesions, T2 morphology is dominant. This zone-based approach reflects the fact that BPH creates background diffusion restriction in the TZ, making T2 morphology more specific for malignancy in that location.

When does DCE change the PI-RADS category?

In the peripheral zone only, positive focal early enhancement can upgrade a DWI score 3 lesion from PI-RADS 3 to PI-RADS 4. DCE does not drive transition zone scoring. If contrast is not administered (biparametric MRI), a PZ DWI 3 lesion cannot be upgraded and remains PI-RADS 3.

What does a PI-RADS 3 score mean clinically?

PI-RADS 3 is an intermediate or equivocal category indicating that clinically significant prostate cancer is possible but uncertain. Management depends on clinical context including PSA density, prior biopsy results, and patient risk profile. PSA density is particularly useful for stratifying PI-RADS 3 findings.

PI-RADS v2.1 Assistant | Prostate MRI Toolkit

1. Lesion location

Select lesion location. Choose multiple zones only if the lesion crosses boundaries or the origin is uncertain.

Click the image or the zone descriptions to select zone(s).

Selected zone(s)-

Dominant sequence-

DCE role-

Contrast administered? Determines DCE availability

Why zone matters: PI-RADS scoring depends on lesion location. Peripheral zone lesions follow a DWI/ADC-dominant pathway, while transition zone and anterior lesions follow a T2 morphology-dominant pathway. Read the overview.

Choose a lesion location to set the suggested workflow order.

ADC / high b-value DWI descriptor Dominant sequence for PZ DWI/ADC technically inadequate

T2 morphology descriptor Dominant sequence for TZ / anterior pathway

If a lesion crosses zones, choose the single T2 description that best matches the lesion morphology. The PZ pathway still follows DWI ± DCE; this T2 selection lets the assistant calculate the TZ/anterior pathway.

DCE behavior Only changes PZ lesions when DWI is 3

DCE will be ignored unless a peripheral-zone calculation has DWI score 3.

Size / invasive behavior modifier Applies only through PI-RADS v2.1 rules

Quick guide

PI-RADS v2.1 Quick Guide

PI-RADS v2.1 is a standardized prostate MRI scoring system used to estimate the likelihood of clinically significant prostate cancer and communicate findings consistently.

PI-RADS v2.1 score descriptions chart showing peripheral zone and transition zone decision logic — PI-RADS v2.1 quick reference: peripheral zone and transition zone score descriptions.

Peripheral zone: DWI is dominant

Peripheral zone lesions are scored primarily by ADC and high b-value DWI. A focal lesion that is dark on ADC and bright on high b-value DWI is more suspicious than a vague, linear, wedge-shaped, or diffuse abnormality.

Transition zone: T2 is dominant

Transition zone lesions are scored primarily by T2 morphology. Suspicious features include a lenticular or non-circumscribed shape, homogeneous moderate T2 hypointensity, and more invasive behavior. DWI can modify selected borderline TZ lesions, but it is not the dominant sequence.

When does DCE matter?

DCE has a limited but important role. In the peripheral zone, positive focal early enhancement can upgrade an otherwise PI-RADS 3 lesion to PI-RADS 4. DCE generally does not drive transition zone scoring.

Image quality caveat

If DWI or DCE is technically inadequate or not performed, PI-RADS assigns that component an “X.” Inadequate DWI is a major limitation, especially for peripheral-zone assessment. If DWI and DCE are both inadequate or absent, assessment should be limited to staging for extraprostatic extension.

When DWI/ADC Is Nondiagnostic

Susceptibility artifact, commonly related to adjacent rectal gas, may render DWI and ADC nondiagnostic. In this setting, the DWI score may be recorded as X. An overall PI-RADS category may still be assigned when T2-weighted imaging and DCE are adequate, using the PI-RADS v2.1 Assessment Without Adequate DWI pathway. The report should describe the technical limitation and acknowledge reduced diagnostic confidence. Repeat DWI should be considered when the cause of artifact can be corrected. If DCE is also inadequate or absent, a standard lesion PI-RADS category should not be assigned, and assessment is limited to evaluation for extraprostatic extension.

Reporting language example

DWI/ADC evaluation is nondiagnostic due to susceptibility artifact from adjacent rectal gas. DWI score: X. Overall PI-RADS category assigned using the PI-RADS v2.1 assessment pathway for technically inadequate DWI. This limitation reduces diagnostic confidence.

Bottom line

Remember the workflow: DWI drives peripheral zone scoring, T2 drives transition zone scoring, and DCE mainly helps decide whether a peripheral zone PI-RADS 3 lesion should be upgraded. PI-RADS should always be interpreted with the full MRI exam, sequence quality, PSA density, prior biopsy history, and clinical context.

References and further reading

About this article This educational article was written by Nicholas H. Shaheen, MD for the Prostate MRI Toolkit. It is intended for teaching and reference, is not peer reviewed, and should not replace local practice standards, institutional protocols, or formal society guidelines. Last updated: June 2026

PI-RADS v2.1
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PI-RADS Interactive Visual Guide