Research Service, VA San Diego Healthcare System, San Diego, CA, USA; Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA.
Research Service, VA San Diego Healthcare System, San Diego, CA, USA; Department of Bioengineering, University of California, San Diego, San Diego, CA, USA.
Ultrasound Med Biol. 2024 Aug;50(8):1287-1291. doi: 10.1016/j.ultrasmedbio.2024.04.004. Epub 2024 May 8.
To compare the effectiveness of positive pressure (PP) and negative pressure (NP) for reducing gas inclusions in biological tissues in preparation for acoustic imaging.
Eighteen pieces of porcine liver in degassed saline were included in this study. For the PP group (n = 9 samples), a wristwatch waterproof tester was used to pressurize samples to 0.41 MPa (59 psi) for 10 min. For the NP group (n = 9 samples), a desiccator at -0.08 MPa (-12 psi) was used for 30 min. Backscatter coefficients (BSCs) were calculated over the central frequency range of the backscattered spectra and paired-samples t-tests were performed.
Utilization of PP resulted in a decrease in BSC for all samples, indicating less gas post-PP (pre-PP -13.0 ± 4.3 dB [mean ± SD], post-PP -18.9 ± 5.0 dB, p = .001). Utilization of NP resulted in an increase in BSC for the majority of samples (pre-NP -14.6 ± 6.0 dB, post-NP -13.1 ± 5.3 dB, p = .177).
Utilization of a simple PP chamber consistently resulted in a decrease in tissue gas, at lower pressures than previously reported. The vacuum method is ineffective, may result in a paradoxical increase in tissue gas, and may not be recommended for tissue degassing.
比较正压（PP）和负压（NP）在减少生物组织中气体包裹方面的效果，为声学成像做准备。
本研究纳入了 18 块脱气盐水中的猪肝。对于 PP 组（n = 9 个样本），使用手表防水测试仪将样本加压至 0.41 MPa（59 psi）持续 10 分钟。对于 NP 组（n = 9 个样本），使用干燥器在-0.08 MPa（-12 psi）下处理 30 分钟。计算背散射谱中心频率范围内的背散射系数（BSC），并进行配对样本 t 检验。
所有样本使用 PP 后 BSC 降低，表明 PP 后气体减少（PP 前-13.0 ± 4.3 dB [均值 ± 标准差]，PP 后-18.9 ± 5.0 dB，p =.001）。大多数样本使用 NP 后 BSC 增加（NP 前-14.6 ± 6.0 dB，NP 后-13.1 ± 5.3 dB，p =.177）。
使用简单的 PP 室可始终如一地降低组织气体，压力低于之前的报道。真空法无效，可能导致组织气体反常增加，不建议用于组织脱气。
