Magnetic field gradients in the MRI suite and their effects on aneurysm clips.

Neurological research · 1996 · Mixed · Low evidence

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MixedLow evidencePaper 4204

Study snapshot

PublicationNeurological research · 1996

Study typeother

Reported directionMixed

Evidence ratingLow

Abstract

We studied magnetic field intensity in the magnetic resonance imaging suite at our hospital and its possible effect on several different types of aneurysm clips, including one Heifetz 17-7 PH, six Heifetz Elgiloy, one Mayfield, six Perneczky, fifteen Sugita, one Sundt-Kees Variangle, four Variangle-McFadden and fifteen Yasargil clips. We carefully observed the clips for any translational or rotational movements along the path from the door towards the magnetic resonance imaging gantry. The magnetic field strength was 0.04 kiloGauss at the entrance of the room, with an acute increase of magnetic strength at 310 cm away from the entrance to the room, 90 cm to the entrance of the gantry. The magnetic strength continued to increase at a rate of 1.0-1.5 kiloGauss for every 20 cm up to the entrance to the gantry. No movement was observed in any of the clips at the entrance to the suite except for the Heifetz 17-7 PH clip, which showed small movement in the longitudinal plane of the clip. At the entrance to the gantry, the Heifetz 17-7 PH, Sundt-Kees Variangle, and Mayfield clips were aligned on the walls of the test container perpendicular to the magnetic bore. The, Heifetz Elgiloy, Perneczky, Sugita, Variangle-McFadden, and Yasargil clips showed no movement throughout the path of the stretcher or near the gantry.

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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 typeother

Effect directionmixed

PopulationNot supplied

Sample size49

ExposureNot supplied

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Magnetic field strength in the MRI suite was 0.04 kiloGauss at the room entrance and increased sharply approaching the gantry (reported 1.0–1.5 kiloGauss per 20 cm). Most clip types (Heifetz Elgiloy, Perneczky, Sugita, Variangle-McFadden, Yasargil) showed no observed movement along the path or near the gantry; small movement was observed for the Heifetz 17-7 PH at the suite entrance, and at the gantry entrance the Heifetz 17-7 PH, Sundt-Kees Variangle, and Mayfield clips aligned perpendicular to the magnetic bore.

Outcomes measured

Translational movement of aneurysm clips in MRI suite magnetic field gradient
Rotational/alignment movement of aneurysm clips near MRI gantry

Limitations

Single-hospital MRI suite measurements; generalizability to other MRI systems/suites not stated
Observational assessment of movement; measurement methods/quantification of forces not described in abstract
No information on repeated trials, blinding, or inter-observer reliability in the abstract
MRI system field strength (e.g., 1.5T) not specified in the abstract

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "MRI suite (static magnetic field gradients)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": 49,
  "outcomes": [
    "Translational movement of aneurysm clips in MRI suite magnetic field gradient",
    "Rotational/alignment movement of aneurysm clips near MRI gantry"
  ],
  "main_findings": "Magnetic field strength in the MRI suite was 0.04 kiloGauss at the room entrance and increased sharply approaching the gantry (reported 1.0–1.5 kiloGauss per 20 cm). Most clip types (Heifetz Elgiloy, Perneczky, Sugita, Variangle-McFadden, Yasargil) showed no observed movement along the path or near the gantry; small movement was observed for the Heifetz 17-7 PH at the suite entrance, and at the gantry entrance the Heifetz 17-7 PH, Sundt-Kees Variangle, and Mayfield clips aligned perpendicular to the magnetic bore.",
  "effect_direction": "mixed",
  "limitations": [
    "Single-hospital MRI suite measurements; generalizability to other MRI systems/suites not stated",
    "Observational assessment of movement; measurement methods/quantification of forces not described in abstract",
    "No information on repeated trials, blinding, or inter-observer reliability in the abstract",
    "MRI system field strength (e.g., 1.5T) not specified in the abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "MRI",
    "static magnetic field",
    "magnetic field gradient",
    "aneurysm clips",
    "translational movement",
    "rotational movement",
    "gantry"
  ],
  "suggested_hubs": [
    {
      "slug": "mri-safety",
      "weight": 0.9,
      "reason": "Study measures MRI suite magnetic field gradients and observes aneurysm clip movement/alignment near the gantry."
    }
  ]
}

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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: 10.1080/01616412.1996.11740458
PubMed: 8985946

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