MaRIA Magnetic Resonance Index of Activity for Crohn disease

{
  "categories": [
    {
      "outcome_code": "inactive",
      "segmental_MaRIA": "less_than_7",
      "endoscopic_reference": "no_active_endoscopic_lesion_detected_in_the_scored_segment"
    },
    {
      "outcome_code": "active",
      "segmental_MaRIA": "greater_than_or_equal_to_7",
      "endoscopic_reference": "endoscopic_lesion_of_any_severity",
      "nesting": "includes_segments_that_also_meet_the_severe_threshold"
    },
    {
      "outcome_code": "severe",
      "segmental_MaRIA": "greater_than_or_equal_to_11",
      "endoscopic_reference": "superficial_or_deep_ulceration",
      "nesting": "subset_of_active_not_a_disjoint_third_state"
    }
  ],
  "applicability": {
    "use_for": "Quantifying inflammatory activity in the terminal ileum and five colonic segments on an adequately performed contrast-enhanced MR enterography examination in known or suspected ileocolonic Crohn disease.",
    "classification_unit": "one_named_bowel_segment_at_one_timepoint; global_MaRIA_is_the_sum_of_all_six_segmental_scores",
    "original_six_segments": [
      "terminal_ileum",
      "ascending_colon",
      "transverse_colon",
      "descending_colon",
      "sigmoid_colon",
      "rectum"
    ],
    "required_inputs": [
      "segment_name",
      "maximum_mural_thickness_mm",
      "pre_gadolinium_wall_signal",
      "post_gadolinium_wall_signal",
      "pre_and_post_noise_standard_deviation",
      "mural_edema_present_or_absent",
      "ulceration_present_or_absent",
      "adequate_distension",
      "motion_and_sequence_adequacy",
      "comparison_protocol_and_date"
    ],
    "outside_scope": [
      "perianal_fistula_activity",
      "upper_GI_or_jejunal_thresholds_without_validation_context",
      "fibrosis_quantification",
      "stricture_or_penetrating_complication_grade",
      "clinical_Crohn_diagnosis_from_MRI_alone",
      "automatic_treatment_selection",
      "individual_prognosis"
    ]
  },
  "original_segmental_formula": {
    "equation": "1.5_times_wall_thickness_mm_plus_0.02_times_RCE_plus_5_times_edema_binary_plus_10_times_ulceration_binary",
    "wall_thickness_mm": "Maximum mural thickness measured perpendicular to the bowel axis in the named segment.",
    "edema_binary": "1 when mural T2 hyperintensity relative to psoas muscle is present, otherwise 0.",
    "ulceration_binary": "1 when a depression or irregularity in the inner surface of a thickened segment, including a linear enhancing fissure, is present, otherwise 0.",
    "RCE_equation": "((wall_signal_post_minus_wall_signal_pre)_divided_by_wall_signal_pre)_times_100_times_(noise_SD_pre_divided_by_noise_SD_post)",
    "ROI_rule": "Use comparable wall regions of interest before and after gadolinium and retain acquisition timing and noise correction; do not substitute visual enhancement for a numeric RCE while still calling the result original MaRIA."
  },
  "calculation_and_assignment_algorithm": [
    {
      "priority": 1,
      "if": "any_required_component_or_original_contrast_sequence_is_missing_or_unreliable",
      "output": "MaRIA_not_calculable_with_missing_component_named"
    },
    {
      "priority": 2,
      "action": "calculate_each_segmental_MaRIA_from_the_original_formula_before_rounding"
    },
    {
      "priority": 3,
      "if": "segmental_MaRIA_greater_than_or_equal_to_11",
      "output_codes": [
        "active",
        "severe"
      ]
    },
    {
      "priority": 4,
      "if": "segmental_MaRIA_greater_than_or_equal_to_7_and_less_than_11",
      "output_code": "active"
    },
    {
      "priority": 5,
      "if": "segmental_MaRIA_less_than_7",
      "output_code": "inactive"
    },
    {
      "priority": 6,
      "action": "sum_the_six_segmental_values_only_when_all_intended_segments_and_protocol_are_defined",
      "output": "global_MaRIA_continuous_value"
    }
  ],
  "decisive_boundaries": {
    "exactly_7": "Active; the threshold is inclusive.",
    "exactly_11": "Active and severe; severe is nested within active.",
    "segmental_only": "The 7 and 11 cutoffs apply to a segmental MaRIA score. Never apply them to the global six-segment sum.",
    "continuous_score": "Retain the numeric segmental score even when a label is returned; small measurement changes around a threshold should remain visible."
  },
  "acquisition_and_validity_gate": {
    "original_protocol": "The derivation used T2 plus pre- and post-gadolinium T1 imaging, oral contrast and active colonic distension with water enema.",
    "distension_limit": "Inadequate luminal distension can mimic or obscure wall thickening. The 2018 guideline noted uncertainty about maintaining the original diagnostic accuracy without colonic distension.",
    "gadolinium_rule": "Original MaRIA requires quantitative contrast enhancement. If gadolinium is omitted, report that original MaRIA is unavailable and use a separately named validated noncontrast index only when its own inputs are present.",
    "longitudinal_rule": "For serial comparison, retain field strength, bowel preparation and distension, sequence timing, contrast use, segment definitions and reader method; protocol drift can change the score independently of biology."
  },
  "original_versus_simplified_MaRIA": {
    "original": "Uses continuous wall thickness and RCE plus binary edema and ulceration; active at 7 or more and severe at 11 or more per segment.",
    "simplified": "sMaRIA equals 1 point for wall thickness over 3 mm, 1 for edema, 1 for fat stranding and 2 for ulcers; active at 1 or more and severe at 2 or more per segment.",
    "no_crosswalk": "MaRIA and sMaRIA are different validated indices. Never use sMaRIA inputs or thresholds while labeling the result original MaRIA, and never convert one score arithmetically into the other."
  },
  "inflammation_damage_and_complication_boundary": {
    "inflammation": "MaRIA estimates mural inflammatory activity relative to an endoscopic reference; it is not a direct histologic or full-thickness biomarker.",
    "fibrosis": "Wall thickening or enhancement cannot by itself partition inflammation from fibrosis. Do not label a stricture inflammatory or fibrotic from the MaRIA total.",
    "complications_separate": [
      "stricture_length_and_prestenotic_dilatation",
      "obstruction",
      "fistula_or_sinus_tract",
      "abscess_or_phlegmon",
      "perforation",
      "bleeding",
      "perianal_disease",
      "extraintestinal_findings"
    ],
    "extent_separate": "The global sum mixes activity and extent; preserve each segmental value and affected length rather than reporting only one total."
  },
  "management_boundary": {
    "appropriate_use": "Use segmental and global measurements as objective imaging evidence in multidisciplinary monitoring, paired with symptoms, biomarkers, endoscopy when indicated, complications and prior therapy.",
    "contemporary_context": "MRE and intestinal ultrasound are central noninvasive monitoring tools in the 2025 multisociety guideline, while formal imaging scores remain most established for standardized assessment and clinical trials.",
    "no_threshold_treatment": "No MaRIA threshold independently starts, stops, escalates or de-escalates corticosteroid, immunomodulator, biologic, small-molecule, nutritional or surgical therapy.",
    "inactive_guard": "A segment below 7 does not prove whole-patient remission, mucosal healing in unscored bowel, absence of fibrosis or freedom from complications.",
    "severe_guard": "A segment at or above 11 indicates an ulcerative reference phenotype, not automatically a clinical emergency, hospitalization criterion or operation indication."
  },
  "risk_and_response_boundary": {
    "no_personal_prognosis": "The score and cutoffs do not directly predict an individual's hospitalization, surgery, cancer, relapse or bowel-damage risk.",
    "cohort_metrics": "Published sensitivity, specificity, accuracy and correlations are cohort properties tied to protocol and reference standard; do not attach them as personal probabilities.",
    "response": "A change can support treatment-response assessment only with comparable protocols and timing. Do not invent a universal minimal important change or transmural-healing threshold from a single score pair."
  },
  "agent_output_contract": [
    "Return protocol, contrast and distension adequacy, field strength, comparison date and every scored segment.",
    "Return wall thickness, pre/post signal measurements, noise correction, calculated RCE, edema and ulceration before the score.",
    "Return continuous segmental MaRIA, active threshold state and severe nested state for each segment.",
    "Return the global sum only with its included segments and never apply 7 or 11 to the global value.",
    "Return affected length, strictures, penetrating complications and perianal disease outside the MaRIA formula.",
    "Name original MaRIA versus sMaRIA explicitly and never mix their components or cutoffs.",
    "Keep imaging activity, symptoms, biomarkers, endoscopy, prognosis and treatment decisions separate."
  ],
  "missing_input_behavior": [
    "If gadolinium or a reliable RCE component is absent, do not calculate original MaRIA.",
    "If a segment is collapsed or motion-degraded, mark it unscorable rather than treating apparent thickness as activity.",
    "If ulceration is equivocal, preserve the resulting numeric interval or uncertainty because the binary term changes the score by 10 points.",
    "If not all six original segments were assessed, do not present the partial sum as a standard global MaRIA without naming the omissions.",
    "If a query supplies only the total, do not infer which segment is active, ulcerated or complicated."
  ],
  "supporting_sources": [
    {
      "role": "derivation",
      "citation": "Rimola et al. Gut. 2009;58:1113-1120",
      "doi": "10.1136/gut.2008.167957",
      "pmid": "19136510"
    },
    {
      "role": "validated_threshold_and_protocol_guidance",
      "citation": "Sturm et al. J Crohns Colitis. 2019;13:273-284",
      "doi": "10.1093/ecco-jcc/jjy114"
    },
    {
      "role": "current_MRE_score_context",
      "citation": "Bhatnagar et al. J Crohns Colitis. 2024;18:1450-1463",
      "doi": "10.1093/ecco-jcc/jjae042"
    },
    {
      "role": "current_multisociety_monitoring_guideline",
      "citation": "Kucharzik et al. and Yanai et al. J Crohns Colitis. 2025;19:jjaf106-jjaf107",
      "dois": [
        "10.1093/ecco-jcc/jjaf106",
        "10.1093/ecco-jcc/jjaf107"
      ]
    }
  ]
}