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Keros

classification of olfactory fossa depth

Side-specific CT classification of olfactory-fossa depth from the vertical height of the lateral lamella of the cribriform plate: type I up to 3 mm, type II over 3 through 7 mm and type III over 7 mm. Return the continuous measurement and all other skull-base hazards; Keros is one anatomic descriptor, not a complete surgical-risk score or a treatment rule.

vigenteKeros / sinonasal and skull-base imaging literature1962 depth framework; preoperative CT limitations reviewed through 20201962CT
Fonte primária3 categorias
IType I, olfactory fossa depth up to 3 mmIIType II, depth over 3 through 7 mmIIIType III, depth over 7 mm (classically 8-16 mm)

Aplicar o Keros a um achado

Descreva o achado como no laudo. A resposta aponta uma das categorias publicadas, com a probabilidade e o trecho que a decide.

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Categorias

Reescritas a partir da fonte e citadas
I
1 de 3

Type I, olfactory fossa depth up to 3 mm

Keros type I: side-specific olfactory-fossa depth up to 3 mm, measured on coronal bone-window CT as the vertical difference between the cribriform plate and ethmoid roof represented by the lateral-lamella height. Return the continuous value, side and measurement location.

CondutaFor preoperative planning, report the side-specific type and depth together with asymmetry, low skull-base side, lateral-lamella length and angle, dehiscence and the remaining CLOSE landmarks. Type I does not waive careful review or select a surgical technique.
RiscoTraditionally the shallowest group, but not a safe-skull-base label. Type-I patients can have a long or acutely angled lateral lamella, a low or reverse-sloping roof, asymmetry or dehiscence; Keros alone supplies no individual injury probability.
verificadoOlfactory fossa depth classification (Keros), reproduced in a CT analysis of 1200 patientsSouza et al., PMC6319094, Keros type I depth definition and measurement method; O'Brien et al. 2016, DOI 10.1148/radiol.2016152230, Figures 8-9 and CLOSE checklist; Hamour et al. 2020, DOI 10.1055/s-0040-1716690, type-I safety limitation.
II
2 de 3

Type II, depth over 3 through 7 mm

Keros type II: side-specific olfactory-fossa depth greater than 3 mm and up to 7 mm, measured as the vertical cribriform-plate-to-ethmoid-roof difference on a true or high-quality coronal CT reformation. Preserve millimeters rather than only the ordinal type.

CondutaCommunicate the measured right and left anatomy and all coexisting skull-base hazards to the operating team. The intermediate depth is one planning input and does not by itself require navigation, alter the operative corridor or mandate or prohibit surgery.
RiscoIntermediate depth exposes a longer lateral-lamella component than type I in the classic model, but complication risk also depends on side asymmetry, roof height and slope, lamellar angle and length, artery course, dehiscence and procedure. No calibrated risk percentage follows from type II.
verificadoOlfactory fossa depth classification (Keros), reproduced in a CT analysis of 1200 patientsSouza et al., PMC6319094, type II 4-7 mm description and bilateral measurements; O'Brien et al. 2016, DOI 10.1148/radiol.2016152230, coronal measurement and operative-hazard checklist; Hamour et al. 2020, PMC8824605, multidimensional limits.
III
3 de 3

Type III, depth over 7 mm (classically 8-16 mm)

Keros type III: side-specific olfactory-fossa depth greater than 7 mm, classically reported as 8-16 mm, with a deep fossa and long vertical lateral-lamella component. Report the exact depth and side and inspect for anterior-posterior variation.

CondutaExplicitly highlight the deep side and associated skull-base anatomy for preoperative planning, while separately reporting dehiscence, asymmetry and CLOSE landmarks. The type increases anatomic caution but does not alone cancel surgery, choose instrumentation or prescribe an approach.
RiscoThe classic deep-fossa warning is associated with greater vulnerability to lateral-lamella penetration and cerebrospinal-fluid leak during endoscopic surgery. It is an anatomic association rather than a personal complication probability, and other hazards can dominate in any Keros type.
verificadoOlfactory fossa depth classification (Keros), reproduced in a CT analysis of 1200 patientsSouza et al., PMC6319094, type III 8-16 mm and dangerous-ethmoid discussion; O'Brien et al. 2016, DOI 10.1148/radiol.2016152230, Keros and asymmetry figures; Hamour et al. 2020, DOI 10.1055/s-0040-1716690, warning against single-metric risk assessment.
Lógica de decisão estruturada

Return one measurement and type per side, plus asymmetry and the remaining skull-base hazards. Keros describes depth only: type III is the traditional deep-fossa warning, but no type is intrinsically safe and no type alone determines surgery.

{
  "categories": [
    {
      "outcome_code": "I",
      "olfactory_fossa_depth_mm": "less_than_or_equal_to_3",
      "lateral_lamella": "short_depth_component",
      "traditional_label": "shallow"
    },
    {
      "outcome_code": "II",
      "olfactory_fossa_depth_mm": "greater_than_3_and_less_than_or_equal_to_7",
      "lateral_lamella": "intermediate_depth_component",
      "traditional_label": "intermediate"
    },
    {
      "outcome_code": "III",
      "olfactory_fossa_depth_mm": "greater_than_7",
      "original_reported_range_mm": "8_to_16",
      "lateral_lamella": "long_depth_component",
      "traditional_label": "deep"
    }
  ],
  "applicability": {
    "use_for": "Anatomic description of each olfactory fossa on high-resolution coronal reformatted CT, especially during preoperative evaluation for endoscopic sinus or skull-base surgery.",
    "classification_unit": "one_side_at_one_anterior_posterior_location_with_right_and_left_reported_separately",
    "required_inputs": [
      "thin_section_bone_algorithm_CT",
      "true_coronal_or_high_quality_coronal_reformation",
      "side",
      "vertical_cribriform_plate_level",
      "ethmoid_roof_level",
      "continuous_depth_mm",
      "measurement_location",
      "skull_base_symmetry",
      "lateral_lamella_length_and_angle_when_relevant",
      "anterior_ethmoid_artery_course",
      "adjacent_dehiscence_or_postoperative_distortion"
    ],
    "outside_scope": [
      "sinus_inflammatory_burden",
      "diagnosis_of_chronic_rhinosinusitis",
      "complete_FESS_risk_prediction",
      "automatic_operability_or_navigation_decision",
      "grading_olfactory_function",
      "applying_population_prevalence_to_an_individual"
    ]
  },
  "measurement_protocol": {
    "definition": "Measure the vertical difference between the cribriform plate and the ethmoid roof, represented by the height of the lateral lamella, on a coronal bone-window image.",
    "side_rule": "Measure and classify right and left independently. Do not average bilateral depths or report only the deeper or shallower side.",
    "location_rule": "Depth and lateral-lamella angle can vary from anterior to posterior; retain the measured location and do not assume one mid-coronal value describes the entire skull base.",
    "boundaries": [
      {
        "if": "depth_mm_less_than_or_equal_to_3",
        "output_code": "I"
      },
      {
        "if": "depth_mm_greater_than_3_and_less_than_or_equal_to_7",
        "output_code": "II"
      },
      {
        "if": "depth_mm_greater_than_7",
        "output_code": "III"
      }
    ],
    "precision_rule": "Return the measured millimeters with the type so borderline values and rounding remain auditable.",
    "technical_failure_rule": "If the cribriform plate or ethmoid roof is obscured, dehiscent, distorted by prior surgery, fracture or mass, or the reconstruction is oblique or too thick, report the limitation and avoid a false precise type."
  },
  "laterality_and_skull_base_context": {
    "asymmetry": "State right-left depth and level asymmetry explicitly; different Keros types can coexist in the same patient and asymmetry itself matters for operative orientation.",
    "low_side_guard": "The side with the more inferiorly positioned skull base can be hazardous even when its numeric Keros type is lower.",
    "additional_features": [
      "lateral_lamella_length",
      "lateral_lamella_horizontal_angle",
      "fovea_ethmoidalis_height_and_slope",
      "cribriform_or_lateral_lamella_dehiscence",
      "anterior_ethmoid_artery_course_and_bony_coverage",
      "lamina_papyracea_integrity",
      "Onodi_cells_and_optic_canal_relationship",
      "sphenoid_pneumatization_and_carotid_or_optic_canal_dehiscence"
    ],
    "CLOSE_mnemonic": {
      "C": "cribriform_plate_and_anterior_skull_base",
      "L": "lamina_papyracea",
      "O": "Onodi_cell",
      "S": "sphenoid_sinus_pneumatization",
      "E": "anterior_ethmoidal_artery"
    }
  },
  "risk_interpretation": {
    "traditional_type_III_signal": "A deep type III fossa has a longer exposed lateral lamella and is traditionally associated with greater vulnerability to penetration and cerebrospinal-fluid leak during endoscopic surgery.",
    "no_safe_type": "Type I is not synonymous with a safe skull base. Long or acutely angled lateral lamellae, a low or reverse-sloping roof, asymmetry, dehiscence and artery exposure can create substantial hazard in any type.",
    "no_probability": "Keros type does not provide a calibrated probability of surgical injury, cerebrospinal-fluid leak, anosmia, meningitis or another complication for an individual.",
    "anatomy_not_outcome": "Observed population frequencies by sex, side or ancestry are descriptive cohorts and must not be used to infer an individual type or outcome without measurement."
  },
  "management_boundary": {
    "appropriate_use": "Communicate the side-specific measurement, type and coexisting skull-base variants to the operating team for preoperative planning and intraoperative orientation.",
    "no_type_specific_order": "No type alone mandates or prohibits surgery, selects the surgical corridor, requires navigation, changes consent or prescribes a technique; those decisions belong to the surgeon and full clinical-anatomic plan.",
    "urgency_guard": "A Keros type on an otherwise routine CT is not an emergency finding. Actual dehiscence, fracture, meningoencephalocele, cerebrospinal-fluid leak or invasive disease is reported separately and can change urgency."
  },
  "agent_output_contract": [
    "Return CT technique, bone reconstruction adequacy and whether anatomy is native, postoperative or distorted.",
    "Return right and left continuous depths, exact measurement locations and separate Keros types.",
    "Return asymmetry, the lower skull-base side, lateral-lamella length or angle when assessable and relevant anterior-posterior variation.",
    "Return the other CLOSE landmarks and any dehiscence, fracture, encephalocele or anterior ethmoid artery exposure separately.",
    "Describe traditional relative hazard without calling type I safe or attaching an individual complication percentage.",
    "Never convert Keros type into Lund-Mackay inflammatory burden or a surgical order."
  ],
  "missing_input_behavior": [
    "If only one side is measurable, report that side and leave the other unclassified rather than assuming symmetry.",
    "If a rounded value lies near 3 or 7 mm, preserve the underlying measurement precision and flag the boundary.",
    "If the image plane is oblique or the roof is incompletely covered, request diagnostic coronal reformations before classification.",
    "If prior surgery, fracture or tumor has altered landmarks, describe the anatomy directly and do not force the native Keros framework.",
    "If only the Keros type is supplied, do not infer the exact depth, side, artery course, dehiscence or total operative risk."
  ],
  "supporting_sources": [
    {
      "role": "original_ranges_reproduced_in_large_CT_series",
      "citation": "Souza et al. Indian J Otolaryngol Head Neck Surg. 2018",
      "pmcid": "PMC6319094"
    },
    {
      "role": "preoperative_CT_reporting_checklist",
      "citation": "O'Brien et al. Radiology. 2016;281:10-21",
      "doi": "10.1148/radiol.2016152230"
    },
    {
      "role": "single_metric_safety_limitation",
      "citation": "Hamour et al. J Neurol Surg B Skull Base. 2020;83:53-58",
      "doi": "10.1055/s-0040-1716690",
      "pmcid": "PMC8824605"
    }
  ]
}

Referência, não é dispositivo médico. Confira a publicação primária vigente. O radiologista que assina o laudo continua autor e responsável.