What this calculator does
Combines lesion zone with T2, diffusion, and dynamic contrast-enhancement scores.
Select the lesion zone and sequence scores. The calculator applies the PI-RADS v2.1 dominant-sequence rules.
Clinical scope
Use PI-RADS v2.1 for multiparametric MRI assessment of the untreated prostate when evaluating the likelihood of clinically significant prostate cancer. The dominant sequence differs between peripheral-zone and transition-zone lesions.
Applicability and exclusions
- The score is not a staging system and does not assess nodal, osseous, or metastatic disease.
- Post-treatment prostate and substantial post-biopsy change require separate interpretation; clinical history, PSA, and prior pathology remain essential.
Method and calculation logic
For peripheral-zone lesions, diffusion is the dominant sequence and dynamic contrast enhancement can upgrade a qualifying score 3 lesion. For transition-zone lesions, T2-weighted imaging is dominant with diffusion used in the specified tie-breaking pathway.
Interpretation table
| Score | Likelihood of clinically significant cancer |
|---|---|
| 1 | Very low |
| 2 | Low |
| 3 | Intermediate / equivocal |
| 4 | High |
| 5 | Very high |
Worked example
Case: Fictional example: a peripheral-zone lesion has DWI score 3 and focal positive dynamic contrast enhancement.
Calculation: Peripheral zone selects DWI as dominant; qualifying positive DCE upgrades the overall assessment from 3 to 4.
Interpretation: Example output: PI-RADS 4. Confirm image quality, lesion measurements, and the complete v2.1 rules before reporting.
How to use this calculator
- Complete the visible imaging and measurement fields. Required inputs are marked in the workbench.
- Review the calculated category, score, measurements, and any recommendation or warning.
- Copy the report-ready text only after checking the result against the complete examination and source guideline.
Calculator-specific questions
Why does lesion zone matter?
Because DWI is dominant in the peripheral zone, while T2-weighted imaging is dominant in the transition zone.
Does PI-RADS include PSA density?
No. PSA density is clinically relevant but is calculated separately and does not change the imaging score itself.
Are patient measurements sent to RadPhrases?
No. Calculator inputs and results are processed in the browser and are not submitted by this page.