PI-RADS Prostate Imaging Reporting and Data System v2.1

{
  "applicability": {
    "purpose": "Detect, localize, characterize, and risk-stratify clinically significant prostate cancer on pretreatment prostate MRI.",
    "clinically_significant_cancer": "Gleason score >=3+4 (grade group >=2), and/or tumor volume >=0.5 cc, and/or extraprostatic extension.",
    "assessment_inputs": "Assign the category from mpMRI findings only; do not incorporate PSA, digital rectal examination, clinical history, or planned treatment into the imaging category."
  },
  "axes": {
    "zone": [
      "peripheral",
      "transition"
    ],
    "dominant_sequence": {
      "peripheral": "DWI_ADC",
      "transition": "T2W"
    },
    "DCE": [
      "positive",
      "negative",
      "inadequate_or_absent"
    ],
    "component_quality": [
      "diagnostic",
      "X_inadequate_or_absent"
    ]
  },
  "sequence_scores": {
    "DWI_ADC": [
      {
        "score": 1,
        "finding": "No abnormality on ADC or high-b-value DWI."
      },
      {
        "score": 2,
        "finding": "Linear or wedge-shaped ADC hypointensity and/or linear or wedge-shaped high-b-value DWI hyperintensity."
      },
      {
        "score": 3,
        "finding": "Focal abnormality discrete from background with ADC hypointensity and/or high-b-value DWI hyperintensity, but not marked on both."
      },
      {
        "score": 4,
        "finding": "Focal markedly low ADC and markedly high high-b-value DWI signal, greatest dimension <15 mm."
      },
      {
        "score": 5,
        "finding": "Same diffusion pattern as score 4 with greatest dimension >=15 mm, or definite extraprostatic extension/invasive behavior."
      }
    ],
    "T2W_transition_zone": [
      {
        "score": 1,
        "finding": "Normal-appearing transition zone or a round completely encapsulated typical nodule."
      },
      {
        "score": 2,
        "finding": "Mostly encapsulated nodule, homogeneous circumscribed nodule without encapsulation, or homogeneous mildly hypointense area between nodules."
      },
      {
        "score": 3,
        "finding": "Heterogeneous signal with obscured margins, including findings that do not qualify as 2, 4, or 5."
      },
      {
        "score": 4,
        "finding": "Lenticular or noncircumscribed homogeneous moderately T2-hypointense focus, greatest dimension <15 mm."
      },
      {
        "score": 5,
        "finding": "Same morphology as score 4 with greatest dimension >=15 mm, or definite extraprostatic extension/invasive behavior."
      }
    ],
    "T2W_peripheral_zone": [
      {
        "score": 1,
        "finding": "Uniform T2 hyperintense signal (normal)."
      },
      {
        "score": 2,
        "finding": "Linear or wedge-shaped hypointensity, or diffuse mild hypointensity, usually with indistinct margins."
      },
      {
        "score": 3,
        "finding": "Heterogeneous signal or a noncircumscribed rounded moderately hypointense focus that does not qualify as 2, 4, or 5."
      },
      {
        "score": 4,
        "finding": "Circumscribed homogeneous moderately T2-hypointense focus confined to the prostate, greatest dimension <15 mm."
      },
      {
        "score": 5,
        "finding": "Same morphology as score 4 with greatest dimension >=15 mm, or definite extraprostatic extension/invasive behavior."
      }
    ],
    "DCE": {
      "positive": "Focal enhancement earlier than or contemporaneous with adjacent normal prostate that corresponds to a suspicious T2W and/or DWI finding.",
      "negative": "No early enhancement, or diffuse/noncorresponding enhancement, or focal enhancement matching a T2W feature of BPH."
    }
  },
  "categories": [
    "1",
    "2",
    "3",
    "4",
    "5"
  ],
  "cells": {
    "peripheral_zone": [
      {
        "DWI_ADC_score": 1,
        "DCE": "any",
        "outcome_code": "1"
      },
      {
        "DWI_ADC_score": 2,
        "DCE": "any",
        "outcome_code": "2"
      },
      {
        "DWI_ADC_score": 3,
        "DCE": "negative",
        "outcome_code": "3"
      },
      {
        "DWI_ADC_score": 3,
        "DCE": "positive",
        "outcome_code": "4"
      },
      {
        "DWI_ADC_score": 4,
        "DCE": "any",
        "outcome_code": "4"
      },
      {
        "DWI_ADC_score": 5,
        "DCE": "any",
        "outcome_code": "5"
      }
    ],
    "transition_zone": [
      {
        "T2W_score": 1,
        "DWI_ADC_score": "any",
        "outcome_code": "1"
      },
      {
        "T2W_score": 2,
        "DWI_ADC_score": "<=3",
        "outcome_code": "2"
      },
      {
        "T2W_score": 2,
        "DWI_ADC_score": ">=4",
        "outcome_code": "3"
      },
      {
        "T2W_score": 3,
        "DWI_ADC_score": "<=4",
        "outcome_code": "3"
      },
      {
        "T2W_score": 3,
        "DWI_ADC_score": 5,
        "outcome_code": "4"
      },
      {
        "T2W_score": 4,
        "DWI_ADC_score": "any",
        "outcome_code": "4"
      },
      {
        "T2W_score": 5,
        "DWI_ADC_score": "any",
        "outcome_code": "5"
      }
    ]
  },
  "inadequate_components": {
    "DWI_ADC_X": {
      "warning": "Usually repeat DWI if the cause can be remedied; otherwise acknowledge the substantial limitation in the report.",
      "fallback_cells": [
        {
          "T2W_score": 1,
          "DCE": "any",
          "outcome_code": "1"
        },
        {
          "T2W_score": 2,
          "DCE": "any",
          "outcome_code": "2"
        },
        {
          "T2W_score": 3,
          "DCE": "negative",
          "outcome_code": "3"
        },
        {
          "T2W_score": 3,
          "DCE": "positive",
          "outcome_code": "4"
        },
        {
          "T2W_score": 4,
          "DCE": "any",
          "outcome_code": "4"
        },
        {
          "T2W_score": 5,
          "DCE": "any",
          "outcome_code": "5"
        }
      ]
    },
    "DCE_X": {
      "peripheral_zone": "Determine the category from the DWI assessment category.",
      "transition_zone": "Use the standard T2W-by-DWI transition-zone matrix."
    },
    "DWI_ADC_and_DCE_X": "Limit assessment to staging for extraprostatic extension; do not infer a lesion PI-RADS category from missing components."
  },
  "management_scope": {
    "rule": "PI-RADS v2.1 does not prescribe management; decisions must incorporate laboratory and clinical history, local expertise, and standards of care.",
    "category_1_2": "The document says biopsy should not be based on PI-RADS 1 or 2 alone.",
    "category_3": "Biopsy may or may not be appropriate depending on factors outside mpMRI.",
    "category_4_5": "Biopsy should be considered, but the final decision remains clinical.",
    "forbidden_inference": "Do not invent PSA-density cutoffs, follow-up intervals, or a biopsy mandate from PI-RADS alone."
  },
  "source_locator": "ACR/ESUR/AdMeTech PI-RADS v2.1 (2019), assessment categories and management scope p 10; zone matrices p 11; inadequate-component tables pp 15-16; T2W scoring p 18; DWI scoring pp 20-21; DCE definition and caveats pp 22-23."
}