The use of PI-RADS vs 2.1 in pre-biopsy multi-parametric (mp) MRI

The aim of this audit is to evaluate reporting practices in accordance with the PI-RADS vs 2.1 guidance on mp MRI reporting in detection of Prostate Cancer.

Prostate cancer is the second leading cause of cancer death in men. The development of multi-parametric (mp) MRI has improved the ability to detect and characterise prostate tumours and is part of the routine investigation of patients with suspected prostate cancer.In order to maintain reporting standards, the Prostate Imaging-Reporting and Data System (PI-RADS) was developed to provide a framework for the acquisition, interpretation and reporting of mpMRI of the prostate.¹

More recently there has been a shift in the investigation of men with suspected cancer to performing the mpMRI before biopsy with reports designed to provide probability of cancer presence and targets for biopsy. MRI has also become the most accurate imaging modality where gland volume can be measured, replacing the transrectal ultrasound. The PSA density, calculated by dividing PSA by gland volume, is a useful parameter in deciding whether to biopsy patients, particularly those with indeterminate lesions on MRI (PIRADS 3/5)^2,3.

In order to maintain high standards of reporting, A joint committee from the European Society of urogenital Radiology (ESUR) and the American College of Urology (ACU) has published an update to the PI-RADS v2 which was then modified to PI-RADS v2.1 in March 2019. This updated version is anticipated that the adoption of these PI-RADS v2.1 modifications will improve inter-reader variability, simplify and standardize PI-RADS assessment of prostate magnetic resonance imaging, enhance interdisciplinary communications with referring clinicians and eventually improve the diagnostic quality of the scan for high risk patients.

The standard: 

All reports of pre-biopsy mpMRI should follow the PI-RADS vs 2.1 guidelines for reporting mpMRI.

The prostate volume should be routinely calculated using the ellipse formula: AP diameter x width x height x 0.52.

PSA density should be routinely calculated using the formula: PSA/Volume.

Up to 4 lesions of PIRADS 3 or greater should be measured on axial plane, localised within the gland and assessed for extra-capsular extension and seminal vesicle invasion.

Lymph node and bony status of the pelvis should be assessed for.

Target: 

PIRADS vs 2.1 scoring system should be applied to 100% of pre-biopsy mpMRI prostate reports.

100% of reports should contain prostate volume and PSA density (if PSA provided in the clinical information). 

100% should contain comment on presence /absence of extracapsular extension, seminal vesicle invasion, presence/absence of suspicious pelvic lymph nodes and suspicious bony lesions.

100% should contain radiological TNM staging if at least 1 lesion of PIRADS 3 or above is described.

Indicators: 

1. The prostate volume and PSA density is calculated

2. If a focal suspicious lesion is described, If so, it is given a PI-RADS score and its maximum size on axial plane and its location are noted

3. The presence of extra-capsular extension, seminal vesicle invasion, suspicious pelvic nodes and bony lesions reported and Radiological TNM staging applied

Data items to be collected: 

Inclusion criteria: 

50 consecutive mpMRI prostate reports to be included and assessed for the aforementioned audit parameters/indicators. Reports can come from outpatient referrals.

Exclusion Criteria:

Benign conditions such as prostatitis and active surveillance for previously known prostate cancer patients to be excluded as the definition of a patient with suspected cancer does not apply to them.

Suggested number: 

50 mpMRI prostate reports

1. Results should be disseminated and discussed amongst the prostate MRI reporters. Plans on how to improve compliance with PI-RADS v2.1 guidelines should be put in place. This part will be under taken by the main audit lead.

2. Audit results will be presented in the departmental quality improvement meeting. This step will be presented by the main audit lead or one of the auditors.

3. Plan for re-audit in 6 month time when reporters hopefully adopt the new recommendations into their own reporting practices. This step will be performed by the main audit lead.

1.    Turkbey B, Rosenkrantz AB, Haider MA, Padhani AR, Villeirs G, Macura KJ, et al. Prostate Imaging Reporting and Data System Version 2.1: 2019 Update of Prostate Imaging Reporting and Data System Version 2. Eur Urol. 2019.

2.    Brizmohun Appayya M, Sidhu HS, Dikaious N et al. Characterizing indeterminate (Likert-score 3/5) peripheral zone prostate lesions with PSA density, PI-RADS scoring and qualitative descriptors on multiparametric MRI. Br J Radiol.2017 Dec 15:20170645.

3.    Brizmohun Appayya M, Adshead J, Ahmed HU, Allen C, Bainbridge A, Barrett T et al. National Implementation of multi-parametric MRI for prostate cancer detection - Recommendations from a UK consensus meeting. BJU International. 2018 Apr 26. Available from, DOI: 10.1111/bju.14361

Dr Mohamed Galal Elsakaan