Three-dimensional numerical simulations of susceptibility-induced magnetic field inhomogeneities in the human head.

Magnetic resonance imaging · 2002 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3840

Study snapshot

PublicationMagnetic resonance imaging · 2002

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Three-dimensional numerical simulations of the static magnetic field in the human head were carried out to assess the field inhomogeneity due to magnetic susceptibility differences at tissue interfaces. We used a finite difference method and magnetic permeability distributions obtained by segmentation of computed tomography images. Computations were carried out for four models, consisting of the head and the neck; the head, neck, and shoulders; the head, neck, and thorax; and the head tilted backwards, including the neck and the shoulders. Considerable magnetic field inhomogeneities were observed in the inferior frontal lobes and inferior temporal lobes, particularly near the sphenoid sinus and the temporal bones. Air/tissue interfaces at the shoulders were found to induce substantial magnetic field inhomogeneities in the occipital lobes and the cerebellum, whereas air/tissue interfaces in the lungs appeared to have less influence on the magnetic field in the brain. Tilting the head backwards could significantly reduce the field inhomogeneities superior to the planum sphenoidale as well as in the occipital lobes and the cerebellum.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationHuman head (computational models based on CT segmentation)

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

3D finite-difference simulations using permeability distributions from segmented CT images found considerable susceptibility-induced static magnetic field inhomogeneities in inferior frontal and inferior temporal lobes, particularly near the sphenoid sinus and temporal bones. Air/tissue interfaces at the shoulders induced substantial inhomogeneities in occipital lobes and cerebellum, while lung air/tissue interfaces had less influence on brain field. Tilting the head backwards could significantly reduce inhomogeneities superior to the planum sphenoidale and in occipital lobes/cerebellum.

Outcomes measured

Static magnetic field inhomogeneity in the human head due to magnetic susceptibility differences at tissue interfaces
Regional distribution of susceptibility-induced field inhomogeneities (e.g., frontal/temporal/occipital lobes, cerebellum)
Effect of body anatomy inclusion (shoulders, thorax, lungs) and head tilt on field inhomogeneity

Limitations

Numerical simulation study; no direct measurements in participants reported in the abstract
No health outcomes assessed; focuses on magnetic field inhomogeneity patterns
Sample size and imaging/segmentation details not provided in the abstract

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "MRI static magnetic field (numerical simulation)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Human head (computational models based on CT segmentation)",
  "sample_size": null,
  "outcomes": [
    "Static magnetic field inhomogeneity in the human head due to magnetic susceptibility differences at tissue interfaces",
    "Regional distribution of susceptibility-induced field inhomogeneities (e.g., frontal/temporal/occipital lobes, cerebellum)",
    "Effect of body anatomy inclusion (shoulders, thorax, lungs) and head tilt on field inhomogeneity"
  ],
  "main_findings": "3D finite-difference simulations using permeability distributions from segmented CT images found considerable susceptibility-induced static magnetic field inhomogeneities in inferior frontal and inferior temporal lobes, particularly near the sphenoid sinus and temporal bones. Air/tissue interfaces at the shoulders induced substantial inhomogeneities in occipital lobes and cerebellum, while lung air/tissue interfaces had less influence on brain field. Tilting the head backwards could significantly reduce inhomogeneities superior to the planum sphenoidale and in occipital lobes/cerebellum.",
  "effect_direction": "unclear",
  "limitations": [
    "Numerical simulation study; no direct measurements in participants reported in the abstract",
    "No health outcomes assessed; focuses on magnetic field inhomogeneity patterns",
    "Sample size and imaging/segmentation details not provided in the abstract"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "static magnetic field",
    "magnetic susceptibility",
    "field inhomogeneity",
    "finite difference method",
    "CT segmentation",
    "human head model",
    "MRI"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1016/s0730-725x(02)00601-x
PubMed: 12591571

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