What is the dominant sequence for the peripheral zone?

Diffusion-weighted imaging (DWI) is the dominant sequence for peripheral zone lesions. Positive dynamic contrast enhancement (DCE) upgrades a PZ DWI score of 3 to PI-RADS 4.

What is the dominant sequence for the transition zone?

T2-weighted imaging (T2W) is the dominant sequence for transition zone lesions. DWI plays a subordinate role and can upgrade a TZ T2W score of 3 to 4 when the DWI finding is clearly abnormal.

What PI-RADS score threshold typically prompts biopsy?

PI-RADS 4 and 5 lesions generally warrant targeted biopsy. PI-RADS 3 is equivocal — clinical risk factors (PSA density, prior biopsy history, family history) usually guide the decision. PI-RADS 1 and 2 do not typically warrant immediate biopsy.

Does this tool diagnose prostate cancer?

No. PI-RADS scoring reflects the probability of clinically significant cancer based on imaging characteristics; it is not a diagnosis. Histopathological confirmation via biopsy is required for diagnosis. This tool is for educational reference only.

What counts as clinically significant prostate cancer in PI-RADS?

PI-RADS v2.1 defines clinically significant cancer as Gleason grade group ≥2 (Gleason score ≥3+4=7) and/or tumor volume ≥0.5 cc and/or extra-prostatic extension.

PI-RADS Helper

Score prostate MRI lesions using the PI-RADS v2.1 system and review criteria, score meanings, and management recommendations.

Step 1 — Select Anatomical Zone

Dominant sequence for PZ: DWI (T2W subordinate)

Step 2 — Select PI-RADS Score

Equivocal

Intermediate probability of clinically significant cancer

Management Guidance

Quick Reference — All Scores

Score	Likelihood	PZ (DWI dominant)	TZ (T2W dominant)

For PZ: DWI score of 3 upgrades to 4 when DCE is positive. For TZ: T2W score of 3 upgrades to 4 if DWI is also markedly abnormal.

Educational reference only. This tool presents PI-RADS v2.1 criteria for learning and reference purposes. It does not diagnose prostate cancer or replace a formal radiology report. Clinical decisions must be made by qualified clinicians with access to the full clinical picture.

Summary

PI-RADS (Prostate Imaging Reporting and Data System) version 2.1 is the standard framework for scoring lesions found on multiparametric prostate MRI (mpMRI). Each lesion receives a score of 1 through 5 based on findings from T2-weighted imaging (T2W) and diffusion-weighted imaging (DWI), with the dominant sequence depending on whether the lesion is in the peripheral zone (PZ) or the transition zone (TZ). A score of 1 or 2 indicates very low or low probability of clinically significant cancer; 3 is equivocal; 4 and 5 indicate high and very high probability, respectively. This tool presents the key criteria for each score and zone so radiologists, urologists, and trainees can review the classification logic quickly.

How it works

Select the anatomical zone — Peripheral Zone (PZ) or Transition Zone (TZ).
The dominant sequence updates automatically: DWI for PZ, T2W for TZ.
Click a PI-RADS score (1–5) to display the criteria for that score in the selected zone.
Read the score interpretation and clinical management guidance below the criteria.
Consult the quick-reference table for a full side-by-side view of all scores.

Use cases

Review PI-RADS v2.1 criteria during mpMRI reporting.
Cross-check a lesion score before finalizing a radiology report.
Study the classification system during radiology or urology training.
Explain PI-RADS findings to a colleague or referring clinician.

Frequently Asked Questions

Last updated: 2026-06-18 · Reviewed by Nham Vu