Assign vascular territories, not just clock-face positions. Preserve multiple involved segments, anatomy variants, uncertainty, and the distinction between anatomic localization and treatment planning.
{
"categories": [
{
"outcome_code": "I",
"section": "caudate",
"position": "dorsal_adjacent_to_IVC",
"portal_tier": "independent"
},
{
"outcome_code": "II",
"section": "left_lateral",
"position": "superior",
"portal_tier": "above_transverse_portal_plane"
},
{
"outcome_code": "III",
"section": "left_lateral",
"position": "inferior",
"portal_tier": "below_transverse_portal_plane"
},
{
"outcome_code": "IV",
"section": "left_medial",
"position": "whole_segment_or_level_unresolved",
"subdivisions": [
"IVa",
"IVb"
]
},
{
"outcome_code": "IVa",
"parent_code": "IV",
"section": "left_medial",
"position": "superior",
"portal_tier": "above_transverse_portal_plane"
},
{
"outcome_code": "IVb",
"parent_code": "IV",
"section": "left_medial",
"position": "inferior",
"portal_tier": "below_transverse_portal_plane"
},
{
"outcome_code": "V",
"section": "right_anterior",
"position": "inferior",
"portal_tier": "below_transverse_portal_plane"
},
{
"outcome_code": "VI",
"section": "right_posterior",
"position": "inferior",
"portal_tier": "below_transverse_portal_plane"
},
{
"outcome_code": "VII",
"section": "right_posterior",
"position": "superior",
"portal_tier": "above_transverse_portal_plane"
},
{
"outcome_code": "VIII",
"section": "right_anterior",
"position": "superior",
"portal_tier": "above_transverse_portal_plane"
}
],
"applicability": {
"use_for": "Anatomic localization of liver parenchyma, focal lesions, vascular territories and segment-oriented interventions on cross-sectional imaging.",
"classification_unit": "lesion_or_parenchymal_territory; multiple segment codes may be required",
"required_inputs": [
"relationship_to_portal_venous_branches",
"relationship_to_middle_right_and_left_hepatic_veins",
"relationship_to_IVC_and_hilum",
"level_relative_to_the_transverse_portal_plane",
"presence_of_anatomic_variant_or_mass_effect"
],
"preferred_basis": "Follow the portal territory and three-dimensional vascular relationships rather than assigning a segment from surface morphology or lesion centroid alone."
},
"anatomic_principles": {
"intrasegmental_structures": "Portal venous branches travel with hepatic arterial and biliary branches inside the supplied segmental territory.",
"intersegmental_structures": "The major hepatic veins generally course in planes between portal territories and serve as practical imaging landmarks, but the vascular boundaries are three-dimensional and variable.",
"functional_midplane": "The middle-hepatic-vein plane from the gallbladder fossa toward the IVC separates functional right liver (V-VIII) from functional left liver (II-IV); this is not the external falciform division.",
"right_intersectional_plane": "The right-hepatic-vein plane separates the right anterior section (V,VIII) from the right posterior section (VI,VII).",
"original_Couinaud_left_scissura": "The left-hepatic-vein/left-portal-scissura model separates original Couinaud's left posterior sector (II) from the left anterior or paramedian sector (III,IV).",
"Brisbane_left_section_rule": "Brisbane does not use that left hepatic-vein sector boundary for its sections: the falciform-ligament/umbilical-fissure plane separates the left lateral section (II,III) from the left medial section (IV).",
"transverse_portal_plane": {
"superior": [
"II",
"IVa",
"VII",
"VIII"
],
"inferior": [
"III",
"IVb",
"V",
"VI"
]
},
"segment_I_exception": "Segment I is the caudate territory, commonly receives portal inflow from both sides and drains directly to the IVC through short hepatic veins; it is not assigned by the superior/inferior pairing rule."
},
"section_map": [
{
"section": "left_lateral",
"segment_codes": [
"II",
"III"
]
},
{
"section": "left_medial",
"segment_codes": [
"IV",
"IVa",
"IVb"
]
},
{
"section": "right_anterior",
"segment_codes": [
"V",
"VIII"
]
},
{
"section": "right_posterior",
"segment_codes": [
"VI",
"VII"
]
},
{
"section": "caudate",
"segment_codes": [
"I"
]
}
],
"terminology_models": {
"original_Couinaud_sectors": [
{
"sector": "left_posterior",
"segment_codes": [
"II"
]
},
{
"sector": "left_anterior_or_paramedian",
"segment_codes": [
"III",
"IV",
"IVa",
"IVb"
]
},
{
"sector": "right_anterior",
"segment_codes": [
"V",
"VIII"
]
},
{
"sector": "right_posterior",
"segment_codes": [
"VI",
"VII"
]
}
],
"Brisbane_2000_sections": [
{
"section": "left_lateral",
"segment_codes": [
"II",
"III"
]
},
{
"section": "left_medial",
"segment_codes": [
"IV",
"IVa",
"IVb"
]
},
{
"section": "right_anterior",
"segment_codes": [
"V",
"VIII"
]
},
{
"section": "right_posterior",
"segment_codes": [
"VI",
"VII"
]
}
],
"safety_rule": "Do not use sector and section as synonyms on the left side; name the convention when surgical anatomy depends on it."
},
"assignment_rules": [
"First determine functional right versus left using the middle-hepatic-vein plane and portal inflow.",
"On the right, determine anterior versus posterior section using the right-hepatic-vein plane and supplying portal branch.",
"On the left, distinguish original Couinaud sectors from Brisbane sections: use the left hepatic scissura for the former and the falciform/umbilical-fissure division for the latter.",
"Then determine superior versus inferior level relative to the portal bifurcation and segmental portal branches.",
"For segment IV, return IVa or IVb when the craniocaudal subdivision is supported; retain IV when the whole segment is involved or the subdivision cannot be resolved.",
"If a lesion crosses a vascular boundary, report every involved segment and identify the dominant portal territory only when demonstrable."
],
"reporting_contract": [
"report_segment_or_segments_and_lobe_or_section",
"state_IVa_or_IVb_when_resolved_without_discarding_parent_segment_context",
"describe_relationship_to_portal_pedicles_hepatic_veins_IVC_hilum_and_bile_ducts_when_relevant",
"state_boundary_crossing_and_anatomic_variants",
"use_right_and_left_as_functional_hemilivers_not_surface_lobes",
"do_not_convert_location_alone_into_resectability_or_treatment"
],
"Brisbane_resection_context": {
"single_segment": "segmentectomy",
"two_contiguous_segments": "bisegmentectomy",
"left_lateral_section": "II_and_III",
"left_medial_section": "IV_including_IVa_and_IVb",
"right_anterior_section": "V_and_VIII",
"right_posterior_section": "VI_and_VII",
"right_hepatectomy_or_hemihepatectomy": "V_through_VIII",
"left_hepatectomy_or_hemihepatectomy": "II_through_IV",
"segment_I_rule": "When segment I is included with another named resection, state with_resection_of_segment_1 or extended_to_segment_1 explicitly.",
"notation_rule": "Brisbane terminology favors Arabic Sg numbers; RadCommons retains Roman outcome codes for API compatibility and exposes the exact mapping here."
},
"version_context": [
{
"date": "1957",
"status": "origin",
"detail": "Couinaud described the classic segmental model in Le foie: etudes anatomiques et chirurgicales."
},
{
"date": "1999",
"status": "anatomic_reassessment",
"detail": "Couinaud supported portal plus hepatic-vein segmentation from a 110-cast anatomic series (PMID 10805544; DOI 10.1159/000018770)."
},
{
"date": "2000",
"status": "terminology_standardization",
"detail": "The IHPBA Brisbane consensus standardized hemiliver, section, segment and resection terminology (DOI 10.1016/S1365-182X(17)30755-4)."
},
{
"date": "2020_consensus_published_2021",
"status": "adjacent_update",
"detail": "Tokyo terminology added definitions for anatomic segmentectomy and subsegmentectomy without replacing the base Couinaud segment map (DOI 10.1002/jhbp.1091)."
}
],
"uncertainty_and_limits": [
"Portal and hepatic venous branching varies, hepatic-vein planes are approximations, and large lesions or prior surgery can distort landmarks; state uncertainty rather than forcing one segment.",
"Some later Couinaud and Brisbane literature uses Sg9 for a paracaval caudate portion. This RadCommons decision system preserves the classic I-VIII output set; when a source uses Sg9, retain that source terminology and request the institutional convention instead of silently mapping it to I or VIII.",
"A segment code provides no biological prognosis and does not by itself determine technical resectability, future liver remnant, operative approach, ablation safety, or oncologic management."
],
"supporting_sources": [
{
"role": "primary_anatomic_reassessment",
"citation": "Couinaud C. Dig Surg. 1999;16:459-467",
"doi": "10.1159/000018770",
"pmid": "10805544"
},
{
"role": "IHPBA_consensus",
"citation": "Strasberg et al. HPB. 2000;2:333-339",
"doi": "10.1016/S1365-182X(17)30755-4"
},
{
"role": "open_anatomic_and_resection_context",
"citation": "Orcutt et al. Front Surg. 2016;3:14",
"doi": "10.3389/fsurg.2016.00014",
"pmcid": "PMC4786552"
},
{
"role": "current_adjacent_terminology",
"citation": "Nagino et al. J Hepatobiliary Pancreat Sci. 2021",
"doi": "10.1002/jhbp.1091"
}
],
"source_locator": "IHPBA Brisbane 2000 consensus, DOI 10.1016/S1365-182X(17)30755-4, Figures 1-4 and division/resection terminology; Couinaud 1999, PMID 10805544, portal and hepatic-vein segmentation; Orcutt et al., PMC4786552, Figures 1-2 and segment-oriented resection text; Tokyo 2020 consensus, DOI 10.1002/jhbp.1091, definitions 1-2."
}