From the Guidelines
PI-RADS (Prostate Imaging-Reporting and Data System) is a standardized scoring system used to evaluate MRI findings of the prostate to detect and classify suspicious lesions that may indicate prostate cancer, with a 5-point scale where higher scores indicate a greater likelihood of clinically significant cancer, as supported by the most recent guidelines 1.
Key Points
- The system uses a 5-point scale where higher scores indicate a greater likelihood of clinically significant cancer, with PI-RADS 1 indicating a very low probability of cancer, PI-RADS 2 suggesting low probability, PI-RADS 3 representing an intermediate/equivocal risk, PI-RADS 4 indicating a high probability, and PI-RADS 5 signifies a very high probability of clinically significant cancer.
- The assessment incorporates findings from T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced MRI, with different sequences given priority depending on the prostate zone being evaluated (peripheral zone versus transition zone) 1.
- For patients with PI-RADS scores of 4 or 5, targeted biopsies are typically recommended, while those with scores of 1 or 2 may avoid unnecessary biopsies, as suggested by recent studies 1.
- PI-RADS 3 lesions often require clinical correlation with other factors like PSA levels and digital rectal exam findings to determine management, as emphasized in the latest guidelines 1.
Management Priorities
- Perform MRI before a confirmatory biopsy if no MRI has been performed before the initial biopsy, as recommended by the latest guidelines 1.
- Take both targeted biopsy (of any PI-RADS 3 lesion) and systematic biopsy if a confirmatory biopsy is performed, as suggested by recent studies 1.
- Consider MRI-targeted biopsy for patients with PI-RADS scores of 4 or 5, as supported by the most recent evidence 1.
From the Research
PI-RADS Prostatic Scores
- The Prostate Imaging Reporting and Data System (PI-RADS) score is a method of risk stratification for men with prostate cancer, using multiparametric MRI (mpMRI) to assign a score indicating the likelihood of clinically significant prostate cancer 2.
- Studies have shown that PI-RADS scores are associated with biochemical control and distant metastasis in men with intermediate-risk and high-risk prostate cancer treated with radiation therapy 2.
- A PI-RADS score of ≤3,4, or 5 has been defined, with a median nodule size of 0,8, and 18 mm, respectively, and men with PI-RADS ≤ 3,4, or 5 disease had 7-year freedom from biochemical failure (FFBF) of 100%, 92%, and 65%, respectively 2.
Prognostic Significance of PI-RADS Scores
- The prognostic significance of PI-RADS scores in prostate cancer patients has been investigated, with results showing that PI-RADS 5 lesions are associated with a significantly poorer postoperative prognosis 3.
- Univariate and multivariable analyses have revealed that PI-RADS scores are independently associated with biochemical recurrence after prostatectomy, with PI-RADS 5 lesions having a higher risk of recurrence compared to PI-RADS 3 or 4 lesions 3.
- PI-RADS scores have also been shown to be associated with prostate cancer upstaging on surgical pathology, with higher PI-RADS scores indicating a higher risk of upstaging 4.
Impact of Visible Tumor on Upgrading and Adverse Pathology
- The impact of visible tumor (PI-RADS ≥ 3) on upgrading and adverse pathology at radical prostatectomy has been investigated, with results showing that PI-RADS 4-5 lesions are independent predictors of upgrading and adverse pathology in low-risk prostate cancer patients 5.
- The number of positive cores and tumor volume have been shown to be significantly associated with upgrading and adverse pathology, with PI-RADS 4-5 lesions having a higher risk of adverse pathology compared to PI-RADS 3 lesions 5.
Risk Stratification of Prostate Cancer According to PI-RADS Categories
- A meta-analysis of prospective studies has shown that PI-RADS version 2 categories can be used for risk stratification of prostate cancer, with pooled detection rates of clinically significant prostate cancer monotonically increasing for each PI-RADS category 6.
- The detection rates of clinically significant prostate cancer have been shown to be 4% for category 1-2,17% for category 3,46% for category 4, and 75% for category 5, with substantial study heterogeneity noted in categories 1-2 and 4 6.