Radiofrequency applicator concepts for thermal magnetic resonance of brain tumors at 297 MHz (7.0 Tesla).

International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group · 2020 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 5638

Study snapshot

PublicationInternational journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group · 2020

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

Thermal intervention is a potent sensitizer of cells to chemo- and radiotherapy in cancer treatment. Glioblastoma multiforme (GBM) is a potential clinical target, given the cancer's aggressive nature and resistance to current treatment options. The annular phased array (APA) technique employing electromagnetic waves in the radiofrequency (RF) range allows for localized temperature increase in deep seated target volumes (TVs). Reports on clinical applications of the APA technique in the brain are still missing. Ultrahigh field magnetic resonance (MR) employs higher frequencies than conventional MR and has potential to provide focal temperature manipulation, high resolution imaging and noninvasive temperature monitoring using an integrated RF applicator (ThermalMR). This work examines the applicability of RF applicator concepts for ThermalMR of brain tumors at 297 MHz (7.0 Tesla). Electromagnetic field (EMF) simulations are performed for clinically realistic data based on GBM patients. Two algorithms are used for specific RF energy absorption rate based thermal intervention planning for small and large TVs in the brain, aiming at maximum RF power deposition or RF power uniformity in the TV for 10 RF applicator designs. For both TVs , the power optimization outperformed the uniformity optimization. The best results for the small TV are obtained for the 16 element interleaved RF applicator using an elliptical antenna arrangement with water bolus. The two row elliptical RF applicator yielded the best result for the large TV. This work investigates the capacity of ThermalMR to achieve targeted thermal interventions in model systems resembling human brain tissue and brain tumors.

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 typeengineering

Effect directionunclear

PopulationClinically realistic data based on glioblastoma multiforme (GBM) patients (simulation/model systems resembling human brain tissue and brain tumors)

Sample sizeNot supplied

ExposureRF · 297 MHz

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

EMF simulations at 297 MHz evaluated 10 RF applicator designs using two SAR-based planning algorithms for small and large brain target volumes. For both target volumes, power optimization outperformed uniformity optimization; the best small-TV result was with a 16-element interleaved elliptical antenna arrangement with water bolus, and the best large-TV result was with a two-row elliptical RF applicator.

Outcomes measured

Electromagnetic field (EMF) simulation results for RF applicator designs
Specific RF energy absorption rate (SAR)-based thermal intervention planning performance
RF power deposition in target volume (TV)
RF power uniformity in target volume (TV)
Identification of best-performing RF applicator designs for small vs large target volumes

Limitations

Reports on clinical applications of the APA technique in the brain are still missing (context suggests limited clinical evidence)
Study is based on EMF simulations/model systems rather than reported clinical outcomes
Sample size and quantitative performance metrics are not provided in the abstract

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "MRI (7.0 Tesla) RF applicator / ThermalMR",
    "frequency_mhz": 297,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Clinically realistic data based on glioblastoma multiforme (GBM) patients (simulation/model systems resembling human brain tissue and brain tumors)",
  "sample_size": null,
  "outcomes": [
    "Electromagnetic field (EMF) simulation results for RF applicator designs",
    "Specific RF energy absorption rate (SAR)-based thermal intervention planning performance",
    "RF power deposition in target volume (TV)",
    "RF power uniformity in target volume (TV)",
    "Identification of best-performing RF applicator designs for small vs large target volumes"
  ],
  "main_findings": "EMF simulations at 297 MHz evaluated 10 RF applicator designs using two SAR-based planning algorithms for small and large brain target volumes. For both target volumes, power optimization outperformed uniformity optimization; the best small-TV result was with a 16-element interleaved elliptical antenna arrangement with water bolus, and the best large-TV result was with a two-row elliptical RF applicator.",
  "effect_direction": "unclear",
  "limitations": [
    "Reports on clinical applications of the APA technique in the brain are still missing (context suggests limited clinical evidence)",
    "Study is based on EMF simulations/model systems rather than reported clinical outcomes",
    "Sample size and quantitative performance metrics are not provided in the abstract"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ThermalMR",
    "hyperthermia",
    "glioblastoma multiforme",
    "brain tumors",
    "7.0 Tesla",
    "297 MHz",
    "RF applicator",
    "annular phased array",
    "electromagnetic field simulations",
    "specific absorption rate",
    "thermal intervention planning",
    "water bolus"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.2,
      "reason": "Involves RF exposure/SAR concepts relevant to EMF safety frameworks, though primarily an engineering hyperthermia/MRI applicator study."
    }
  ]
}

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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: 10.1080/02656736.2020.1761462
PubMed: 32484019

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