Prostate — MRI (PI-RADS, PSA density)

MRIPI-RADS v2.1 (2019)

Multiparametric prostate MRI for elevated PSA or suspected cancer.

Applies to

Multiparametric prostate MRI for detection or staging

Does not apply to

Post-treatment prostate (use assessment for recurrence)
Studies without adequate diffusion-weighted imaging

What to report

Tap an item to check it off while dictating.

1.Prostate volume and PSA density
Report volume (ellipsoid) and calculate PSA density; ≥0.15 raises suspicion.
2.Lesion location
Use the 41-sector map; state the zone (peripheral vs transition) — the dominant sequence differs by zone.
Pitfall: In the transition zone T2 is dominant; in the peripheral zone DWI is dominant.
3.Index lesion size
Maximum diameter of the index lesion on the dominant sequence; ≥15 mm affects the category.
4.Sequence findings
T2, DWI/ADC, and DCE features, combined into a PI-RADS assessment category (1–5).
5.Extraprostatic extension
Capsular contact length, bulge, neurovascular bundle involvement, and seminal vesicle invasion.
6.Nodes and bone
Pelvic lymph nodes and marrow signal for metastatic disease.
7.Study quality
State adequacy: b-value, artifacts, and coil used, since these limit interpretation.

Scores & calculators

Prostate volume

Prostate volume from three orthogonal diameters (ellipsoid method).

Length (AP)

Width (transverse)

Height (craniocaudal)

Complete the inputs to see the result.

Ellipsoid formula V = (π/6) × L × W × H. 1 mL ≈ 1 g of prostate tissue.

PSA density

Serum PSA divided by prostate volume.

Serum PSA

ng/mL

Prostate volume

Complete the inputs to see the result.

PSA density = serum PSA ÷ prostate volume. A threshold of ≥0.15 ng/mL/cc is commonly used but is not universal.

Sources

PI-RADS v2.1 — Turkbey B et al. Eur Urol (2019)

Content review: Content pending clinical review · 2026-07-09

Educational reference for trained clinicians. Verify every result against the cited original guideline before use. Not a substitute for clinical judgment or medical advice.