Thermographic studies of phantom and canine kidneys thawed by microwave radiation.

Cryobiology · 1990 · Mixed · Low evidence

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MixedLow evidencePaper 6264

Study snapshot

PublicationCryobiology · 1990

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

Whole organs, such as kidneys, must be thawed quickly and uniformly to prevent damage during thawing due to excessive heating. Electromagnetic heating with microwaves thaws the kidneys quickly but frequently produces "hot spots" with heat damage. To study heat damage, phantom gelatin kidneys with different dielectric constants and canine kidneys perfused with 12.5% glycerol, ethylene glycol, or dimethyl sulfoxide before freezing were microwave thawed, and the interior temperature was measured by thermography. Phantom kidneys were thawed free standing and canine kidneys were either free standing or packed in a gel mixture. Both phantom and canine kidneys were split symmetrically and separated with a sheet of Styrofoam to facilitate immediate separation and evaluation of the halves after thawing (approximately 3 sec). All the phantoms, regardless of dielectric properties, had areas less than 0 degrees C or greater than 37 degrees C after thawing. The free-standing canine kidneys and the gel-packed ethylene glycol-perfused kidneys had frozen areas (less than 0 degrees C) and hot spots (greater than 37 degrees C). However, glycerol- and dimethyl sulfoxide-perfused kidneys packed in gel before thawing had no areas less than 0 degrees C or greater than 37 degrees C. Altering the geometry from a "kidney shape" to a cylindrical shape with increased volume improved the uniformity of thawing and was more effective than altering the dielectric constant over the range evaluated.

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 typeanimal

Effect directionmixed

PopulationPhantom gelatin kidneys and canine kidneys (perfused with 12.5% glycerol, ethylene glycol, or dimethyl sulfoxide)

Sample sizeNot supplied

Exposuremicrowave

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Microwave thawing produced non-uniform temperature distributions with frozen areas and/or hot spots in all phantom kidneys and in free-standing canine kidneys and gel-packed ethylene glycol-perfused kidneys. Glycerol- and dimethyl sulfoxide-perfused canine kidneys packed in gel showed no areas <0°C or >37°C after thawing. Changing organ geometry to a larger cylindrical shape improved thawing uniformity more than changing dielectric constant over the evaluated range.

Outcomes measured

Thawing uniformity assessed by interior temperature distribution (thermography)
Presence of frozen areas (<0°C) after thawing
Presence of hot spots (>37°C) after thawing

Limitations

No microwave frequency, power, or dosimetry (e.g., SAR) reported in the abstract
Sample size not reported
Outcome focused on temperature distribution/thermal damage risk rather than biological endpoints beyond heating
Animal/phantom model; generalizability to other organs or clinical settings unclear from abstract

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "microwave",
    "source": "microwave radiation (electromagnetic heating)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Phantom gelatin kidneys and canine kidneys (perfused with 12.5% glycerol, ethylene glycol, or dimethyl sulfoxide)",
  "sample_size": null,
  "outcomes": [
    "Thawing uniformity assessed by interior temperature distribution (thermography)",
    "Presence of frozen areas (<0°C) after thawing",
    "Presence of hot spots (>37°C) after thawing"
  ],
  "main_findings": "Microwave thawing produced non-uniform temperature distributions with frozen areas and/or hot spots in all phantom kidneys and in free-standing canine kidneys and gel-packed ethylene glycol-perfused kidneys. Glycerol- and dimethyl sulfoxide-perfused canine kidneys packed in gel showed no areas <0°C or >37°C after thawing. Changing organ geometry to a larger cylindrical shape improved thawing uniformity more than changing dielectric constant over the evaluated range.",
  "effect_direction": "mixed",
  "limitations": [
    "No microwave frequency, power, or dosimetry (e.g., SAR) reported in the abstract",
    "Sample size not reported",
    "Outcome focused on temperature distribution/thermal damage risk rather than biological endpoints beyond heating",
    "Animal/phantom model; generalizability to other organs or clinical settings unclear from abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "microwave thawing",
    "electromagnetic heating",
    "thermography",
    "kidney",
    "phantom model",
    "canine",
    "hot spots",
    "cryobiology",
    "dielectric constant",
    "geometry"
  ],
  "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: 10.1016/0011-2240(90)90030-8
PubMed: 2379417

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