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Post-mortem Tissue Degassing Using Positive Pressure Is Superior to Negative Pressure.
Victor Barrere1, Yuanshan Wu2, Aiguo Han3
1Research Service, VA San Diego Healthcare System, San Diego, CA, USA; Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA.
Ultrasound in Medicine & Biology
|May 9, 2024
Summary
Positive pressure effectively reduces gas in biological tissues for acoustic imaging, unlike negative pressure which may paradoxically increase gas. This study highlights positive pressure as a reliable method for tissue degassing.
Area of Science:
- Biomedical Engineering
- Acoustic Imaging
- Tissue Preparation
Background:
- Gas inclusions in biological tissues can impede acoustic imaging quality.
- Effective tissue degassing is crucial for accurate ultrasound analysis.
Purpose of the Study:
- To compare the efficacy of positive pressure (PP) and negative pressure (NP) in reducing gas inclusions in biological tissues.
- To determine the optimal method for tissue preparation for acoustic imaging.
Main Methods:
- Porcine liver samples were subjected to either PP (0.41 MPa for 10 min) or NP (-0.08 MPa for 30 min) in degassed saline.
- Backscatter coefficients (BSCs) were measured before and after treatment to quantify gas reduction.
- Paired-samples t-tests were used for statistical analysis.
Main Results:
- Positive pressure significantly decreased BSC (p = .001), indicating reduced gas content.
- Negative pressure showed no significant change in BSC (p = .177) and, for most samples, increased gas content.
- PP resulted in a mean BSC decrease from -13.0 ± 4.3 dB to -18.9 ± 5.0 dB.
Conclusions:
- Simple positive pressure chambers effectively reduce tissue gas at lower pressures than previously reported.
- Negative pressure (vacuum) methods are ineffective for tissue degassing and may be counterproductive.
- Positive pressure is recommended for preparing biological tissues for acoustic imaging to minimize gas inclusions.
