# PI-RADS (Prostate Imaging Reporting and Data System)

Source: https://onco.cc/terms/pi-rads/  
OnCo record `pi-rads` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The international scoring system radiologists use to say how likely a prostate MRI finding is to be a serious cancer, from 1 (very unlikely) to 5 (very likely). British NHS reports usually do not use it: NICE asks for a 5-point Likert score instead, and the two look identical on the page and are not the same thing.

## Summary

PI-RADS is a structured reporting system for multiparametric prostate magnetic resonance imaging, developed jointly by the American College of Radiology, the European Society of Urogenital Radiology and the Admetech Foundation. It assigns each suspicious finding an assessment category from 1 to 5 expressing the probability that it is clinically significant cancer, from very low at 1 to very high at 5, and it derives that overall category from scores given separately to the individual sequences: diffusion-weighted imaging with its apparent diffusion coefficient map is the determining sequence in the peripheral zone, T2-weighted imaging is dominant in the transition zone, and dynamic contrast enhancement acts as a tie-break that can move a peripheral-zone 3 to a 4. Clinically significant cancer, in the system's own definition, is Gleason score 7 or above including 3+4 with a prominent but not predominant pattern 4 component, or tumour volume above 0.5 cubic centimetres, or extraprostatic extension. The current version is 2.1, published in 2019 as a consensus revision of version 2 intended to reduce inter-reader variability, with changed guidance on the T2-weighted acquisition plane, diffusion b-values, dynamic contrast temporal resolution, the anterior fibromuscular stroma and the central zone, and the scoring of transition zone category 2.

A reader in Britain will meet a different word for the same job. NICE NG131 recommendation 1.2.2 offers multiparametric magnetic resonance imaging as the first-line investigation for suspected clinically localised prostate cancer and asks that the result be reported on a 5-point Likert scale. Recommendation 1.2.3 offers magnetic resonance imaging-influenced biopsy at a Likert score of 3 or more, and 1.2.4 allows omitting biopsy at Likert 1 or 2 after discussing the risks and benefits and reaching a shared decision, with systematic biopsy offered to anyone who still wants one. The Likert scale is the radiologist's overall subjective judgement of the probability of clinically significant cancer using all available information, including the prostate-specific antigen and the clinical picture; PI-RADS is a prescriptive algorithm that combines per-sequence scores by fixed rules and is intended to be read from the images alone. They share a 1 to 5 range and the same clinical thresholds in practice, and they are not interchangeable scores.

The number a man is given is therefore a probability statement and not a diagnosis. NG131 sets out what the threshold means in the two directions: between 11 and 28 out of 100 people with a low-risk magnetic resonance imaging result turn out to have clinically significant cancer, and between 18 and 23 out of 100 with a low-risk result who are biopsied receive a diagnosis of clinically insignificant cancer. And the score is a per-patient triage judgement, not a map: the same scan that is 93 percent sensitive for whether a man has clinically significant cancer detects only 65 percent of individual clinically significant lesions against whole-mount pathology.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: PI-RADS; PIRADS; PI-RADS v2.1; PI-RADS score; PI-RADS 3; PI-RADS 4; PI-RADS 5; Prostate Imaging Reporting and Data System
- Tags: gu; prostate-glossary

## Notes

- If your NHS report says Likert and not PI-RADS, nothing is missing. NICE NG131 1.2.2 asks for a 5-point Likert scale, which is the radiologist's overall probability judgement using the scan together with the clinical information, and NG131 writes its biopsy thresholds in Likert numbers: 3 or more means a magnetic resonance imaging-influenced biopsy is offered, 1 or 2 means omitting biopsy can be considered after a shared discussion. Many United Kingdom centres report both, and most international literature, private reports and American guidance are in PI-RADS.
- Why 3 is the difficult number in both systems. Category 3 means intermediate, which is to say the scan cannot tell. It is the score at which the decision moves off the image and onto other information: prostate-specific antigen density, family history, previous biopsies and the man's own preferences. NICE does not set a density threshold; it treats density as one of the things weighed in that conversation.
- The score describes a lesion's probability of being clinically significant cancer, not its size, its grade or its danger to the man. Grade comes from the biopsy, stage comes from the scan read against TNM, and the risk band comes from combining grade, prostate-specific antigen and stage.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/PI-RADS
- Turkbey et al., European Urology 2019: Prostate Imaging Reporting and Data System version 2.1, the 2019 update of PI-RADS version 2: https://doi.org/10.1016/j.eururo.2019.02.033
- American College of Radiology: PI-RADS, Prostate Imaging Reporting and Data System (v2.1, a joint development of the ACR, ESUR and the Admetech Foundation): https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Reporting-and-Data-Systems/PI-RADS
- NICE NG131: prostate cancer, diagnosis and management (recommendations): https://www.nice.org.uk/guidance/ng131/chapter/Recommendations
- Ahmed et al., The Lancet 2017 (PROMIS): diagnostic accuracy of multiparametric MRI and TRUS biopsy in prostate cancer: https://doi.org/10.1016/s0140-6736(16)32401-1
- Johnson et al., European Urology 2019: detection of individual prostate cancer foci via multiparametric magnetic resonance imaging: https://doi.org/10.1016/j.eururo.2018.11.031

## Connected records

- key papers: [Detection of individual prostate cancer foci via multiparametric magnetic resonance imaging](https://onco.cc/key-papers/paper-johnson-mpmri-individual-foci-eur-urol-2019/), [PRECISION: MRI-targeted or standard biopsy for prostate cancer diagnosis](https://onco.cc/key-papers/paper-precision-mri-targeted-biopsy-nejm-2018/), [PROMIS: diagnostic accuracy of multiparametric MRI and TRUS biopsy in prostate cancer](https://onco.cc/key-papers/paper-ahmed-promis-multiparametric-mri-lancet-2017/), [Prostate Cancer Screening with PSA and MRI Followed by Targeted Biopsy Only](https://onco.cc/key-papers/paper-goteborg-2-n-engl-j-med-2022/)
- terms: [Gleason score / Grade Group](https://onco.cc/terms/gleason-grade-group/), [PSA (prostate-specific antigen)](https://onco.cc/terms/psa/), [PSA density](https://onco.cc/terms/psa-density/), [Screening](https://onco.cc/terms/screening/), [Template mapping biopsy (transperineal template prostate mapping)](https://onco.cc/terms/template-mapping-biopsy/), [Whole-mount pathology](https://onco.cc/terms/whole-mount-pathology/)
- technologies: [Active surveillance](https://onco.cc/technologies/active-surveillance/), [MRI](https://onco.cc/technologies/mri/), [PSA and MRI-first prostate cancer screening](https://onco.cc/technologies/prostate-screening-psa-mri/)
- cancers: [Localised prostate cancer, high and very high risk](https://onco.cc/cancers/prostate-high-risk/), [Localised prostate cancer, intermediate risk](https://onco.cc/cancers/prostate-intermediate-risk/), [Localised prostate cancer, very low and low risk](https://onco.cc/cancers/prostate-low-risk/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- fronts: [Diagnostics & Biomarkers](https://onco.cc/fronts/diagnostics/), [Early Detection & Screening](https://onco.cc/fronts/early-detection/), [Imaging](https://onco.cc/fronts/imaging/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/), [Overdiagnosis and false alarms](https://onco.cc/bottlenecks/b-overdiagnosis/), [The hardest cancers are found late](https://onco.cc/bottlenecks/b-early-detection/)
- ideas: [MRI-first prostate screening with genetic pre-selection](https://onco.cc/ideas/idea-prev-mri-first-prostate-screening-prs/), [Prostate active surveillance without scheduled biopsies: MRI and blood tests decide](https://onco.cc/ideas/idea-prev-prostate-as-triggered-biopsy/), [Publish a per-lesion miss rate for every prostate MRI service before it is allowed to guide focal treatment](https://onco.cc/ideas/idea-prostate-per-lesion-mri-audit-before-focal-treatment/)

---
JSON: https://onco.cc/api/v1/entities/pi-rads.json