PI-RADS Prostate MRI — Interpretation of Categories
Multiparametric prostate MRI (mpMRI) using the PI-RADS classification system is the gold standard in the diagnosis of prostate cancer. It helps to avoid unnecessary biopsies and detect clinically significant tumours.
What is PI-RADS
PI-RADS (Prostate Imaging — Reporting and Data System) is a standard scale for assessing prostate lesions on MRI. Current version: PI-RADS v2.1 (2019). Each lesion is given a score of 1–5 indicating the likelihood of clinically significant cancer.
The PI-RADS scale — interpretation
| PI-RADS | Risk of cancer | Management |
|---|---|---|
| 1 | Very low (<5%) | No biopsy, PSA monitoring |
| 2 | Low (~10%) | No biopsy, follow-up |
| 3 | Intermediate (~20%) | Individual decision (PSA, age, PSA density) |
| 4 | High (~50%) | MR-fusion-guided biopsy recommended |
| 5 | Very high (>75%) | Biopsy mandatory |
Components of multiparametric prostate MRI
A full examination comprises 3 components:
- High-resolution T2 — anatomy of the peripheral and transitional zones
- DWI (Diffusion-Weighted Imaging) + ADC — detection of cancerous lesions (highest sensitivity)
- DCE (Dynamic Contrast Enhancement) — rapid enhancement of tumour lesions following contrast administration
Indications for prostate MRI
- Elevated PSA > 4 ng/ml (or >3 in younger patients)
- PSA velocity > 0.75 ng/ml/year
- Inconclusive TRUS biopsy results (negative despite high PSA)
- Active surveillance of low-risk prostate cancer
- Planning a targeted biopsy (MR-fusion biopsy)
- Assessment of recurrence following prostatectomy or radiotherapy
- Staging of detected cancer — bladder or lymph node invasion
Preparation for prostate MRI
- 3–4 hours beforehand — a light meal, not a heavy one
- Enema on the evening of the previous day (for better image quality)
- Refrain from sexual intercourse for 3 days beforehand (reduces physiological enhancement)
- Take your usual medication
- Tell the radiologist about any recent prostate biopsies (haematomas make interpretation difficult)
After the scan — what next
You will receive your prostate MRI results with a PI-RADS description within 24–48 hours. These will be interpreted by a urologist, who will decide on:
- Continued monitoring (PI-RADS 1–2)
- Repeating the MRI in 6–12 months (PI-RADS 3 with low risk)
- MR-fusion-guided biopsy (PI-RADS 4–5)
- Further diagnostic tests (PSMA-PET, CT)
Elevated PSA?
Multiparametric prostate MRI according to the PI-RADS v2.1 standard. Report with urological description.
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