Theoretical and experimental investigation of the relationship among SAR, tissues and radio frequencies in MRI.

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) · 2005 · Unclear · Low evidence

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UnclearLow evidencePaper 3587

Using FDTD simulations, average SAR in muscle, brain, and bone increased by 7.49-fold, 10.87-fold, and 12.92-fold, respectively, when magnetic field strength increased from 0.5 T to 3 T. Phantom experiments at 1.5 T and 3 T agreed with simulations within 11% …

Study snapshot

PublicationPhysica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) · 2005

Study typeexposure_assessment

Reported directionUnclear

Evidence ratingLow

Abstract

The specific absorption rates (SAR) of three tissues (muscle, brain, bone) are investigated both theoretically and experimentally for MRI at the first time. Finite difference time domain (FDTD) analysis is used to simulate the average SAR of three tissues at three magnetic field strengths (0.5 T, 1.5 T, 3T). Simulations show that the SAR of muscle, brain and bone increase 7.49 folds, 10.87 folds and 12.92 folds respectively when the magnetic field strength increases from 0.5 T to 3 T. Experiments are carried out to measure SRAS of different phantoms which simulate the three human tissues at 1.5T and 3T. The experiment results agree with the simulation data very well and within only 11% difference.

Machine Enhanced Logic

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 typeexposure_assessment

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Outcomes measured

Specific absorption rate (SAR) in muscle, brain, and bone (simulated and phantom-measured)
Relationship between SAR and MRI magnetic field strength (0.5 T, 1.5 T, 3 T)

Limitations

Radiofrequency (MHz) not reported in abstract
SAR values (e.g., W/kg) not reported; only fold-changes are provided
Experimental measurements were performed on phantoms rather than human tissues
Only three tissue types and limited field strengths (0.5 T, 1.5 T, 3 T) described

View raw extracted JSON

{
  "study_type": "exposure_assessment",
  "exposure": {
    "band": null,
    "source": "MRI",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Specific absorption rate (SAR) in muscle, brain, and bone (simulated and phantom-measured)",
    "Relationship between SAR and MRI magnetic field strength (0.5 T, 1.5 T, 3 T)"
  ],
  "main_findings": "Using FDTD simulations, average SAR in muscle, brain, and bone increased by 7.49-fold, 10.87-fold, and 12.92-fold, respectively, when magnetic field strength increased from 0.5 T to 3 T. Phantom experiments at 1.5 T and 3 T agreed with simulations within 11% difference.",
  "effect_direction": "unclear",
  "limitations": [
    "Radiofrequency (MHz) not reported in abstract",
    "SAR values (e.g., W/kg) not reported; only fold-changes are provided",
    "Experimental measurements were performed on phantoms rather than human tissues",
    "Only three tissue types and limited field strengths (0.5 T, 1.5 T, 3 T) described"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "MRI",
    "specific absorption rate",
    "SAR",
    "FDTD",
    "phantom",
    "muscle",
    "brain",
    "bone",
    "magnetic field strength",
    "0.5 T",
    "1.5 T",
    "3 T"
  ],
  "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/s1120-1797(05)80020-1
PubMed: 18348846

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