Tailoring magnetic field gradient design to magnet cryostat geometry.

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference · 2006 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3482

Study snapshot

PublicationConference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference · 2006

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Eddy currents induced within a magnetic resonance imaging (MRI) cryostat bore during pulsing of gradient coils can be applied constructively together with the gradient currents that generate them, to obtain good quality gradient uniformities within a specified imaging volume over time. This can be achieved by simultaneously optimizing the spatial distribution and temporal pre-emphasis of the gradient coil current, to account for the spatial and temporal variation of the secondary magnetic fields due to the induced eddy currents. This method allows the tailored design of gradient coil/magnet configurations and consequent engineering trade-offs. To compute the transient eddy currents within a realistic cryostat vessel, a low-frequency finite-difference time-domain (FDTD) method using total-field scattered-field (TFSF) scheme has been performed and validated.

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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

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

The paper describes an approach to use eddy currents induced in an MRI cryostat bore constructively with gradient currents to improve gradient uniformity within a specified imaging volume over time. It reports simultaneous optimization of gradient coil current spatial distribution and temporal pre-emphasis, and states that a low-frequency FDTD method with a TFSF scheme was performed and validated to compute transient eddy currents in a realistic cryostat vessel.

Outcomes measured

Gradient field uniformity over time
Transient eddy currents in MRI cryostat bore
Secondary magnetic fields due to eddy currents
Validation of low-frequency FDTD (TFSF) simulation method

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "MRI gradient coils / cryostat bore (eddy currents)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Gradient field uniformity over time",
    "Transient eddy currents in MRI cryostat bore",
    "Secondary magnetic fields due to eddy currents",
    "Validation of low-frequency FDTD (TFSF) simulation method"
  ],
  "main_findings": "The paper describes an approach to use eddy currents induced in an MRI cryostat bore constructively with gradient currents to improve gradient uniformity within a specified imaging volume over time. It reports simultaneous optimization of gradient coil current spatial distribution and temporal pre-emphasis, and states that a low-frequency FDTD method with a TFSF scheme was performed and validated to compute transient eddy currents in a realistic cryostat vessel.",
  "effect_direction": "unclear",
  "limitations": [],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "MRI",
    "gradient coils",
    "cryostat bore",
    "eddy currents",
    "gradient uniformity",
    "pre-emphasis",
    "finite-difference time-domain",
    "FDTD",
    "total-field scattered-field",
    "TFSF"
  ],
  "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: 10.1109/iembs.2006.259223
PubMed: 17945575

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