Zhao Yuning, Czarnota Gregory J, Park Trevor H, Miller Rita J, Oelze Michael L
Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
bioRxiv. 2024 Feb 9:2024.02.07.579320. doi: 10.1101/2024.02.07.579320.
The study aims to assess the capability of Quantitative Ultrasound (QUS) based on the backscatter coefficient (BSC) for classifying disease states, such as breast cancer response to neoadjuvant chemotherapy and quantifying fatty liver disease. We evaluate the effectiveness of an titanium (Ti) bead as a reference target in calibrating the system and mitigating attenuation and transmission loss effects on BSC estimation.
Traditional BSC estimation methods require external references for calibration, which do not account for ultrasound attenuation or transmission losses through tissues. To address this issue, we use an titanium (Ti) bead as a reference target, because it can be used to calibrate the system and mitigate the attenuation and transmission loss effects on estimation of the BSC. The capabilities of the calibration approach were assessed by quantifying consistency of BSC estimates from rabbit mammary tumors (). Specifically, mammary tumors were grown in rabbits and when a tumor reached 1 cm or greater in size, a 2-mm Ti bead was implanted into the tumor as a radiological marker and a calibration source for ultrasound. Three days later, the tumors were scanned with a L-14/5 38 array transducer connected to a SonixOne scanner with and without a slab of pork belly placed on top of the tumors. The pork belly acted as an additional source of attenuation and transmission loss. QUS parameters, specifically effective scatterer diameter (ESD) and effective acoustic concentration (EAC), were calculated using calibration spectra from both an external reference phantom and the Ti bead.
For ESD estimation, the 95% confidence interval between measurements with and without the pork belly layer was (6.0,27.4) using the bead and (114, 135.1) with the external reference phantom. For EAC estimation, the 95% confidence interval were (-8.1, 0.5) for the bead and (-41.5, -32.2) for the phantom. These results indicate that the bead method shows reduced bias in QUS estimates due to intervening tissue losses.
The use of an Ti bead as a radiological marker not only serves its traditional role but also effectively acts as a calibration target for QUS methods. This approach accounts for attenuation and transmission losses in tissue, resulting in more accurate QUS estimates and offering a promising method for enhanced disease state classification in clinical settings.
本研究旨在评估基于背向散射系数（BSC）的定量超声（QUS）对疾病状态进行分类的能力，例如乳腺癌对新辅助化疗的反应以及对脂肪肝疾病进行量化。我们评估了钛（Ti）珠作为参考目标在校准系统以及减轻对BSC估计的衰减和传输损失影响方面的有效性。
传统的BSC估计方法需要外部参考进行校准，而这些方法没有考虑超声通过组织时的衰减或传输损失。为了解决这个问题，我们使用钛（Ti）珠作为参考目标，因为它可用于校准系统并减轻对BSC估计的衰减和传输损失影响。通过量化来自兔乳腺肿瘤（）的BSC估计的一致性来评估这种校准方法的能力。具体而言，在兔体内培育乳腺肿瘤，当肿瘤大小达到1厘米或更大时，将一个2毫米的Ti珠植入肿瘤中作为放射学标记和超声校准源。三天后，使用连接到SonixOne扫描仪的L-14/5 38阵列换能器对肿瘤进行扫描，扫描时在肿瘤上方放置或不放置一块猪肚。猪肚作为额外的衰减和传输损失源。使用来自外部参考体模和Ti珠的校准光谱计算QUS参数，特别是有效散射体直径（ESD）和有效声浓度（EAC）。
对于ESD估计，有猪肚层和没有猪肚层测量之间的95%置信区间，使用Ti珠时为（6.0,27.4），使用外部参考体模时为（114, 135.1）。对于EAC估计，95%置信区间，使用Ti珠时为（-8.1, 0.5），使用体模时为（-41.5, -32.2）。这些结果表明，由于中间组织损失，Ti珠方法在QUS估计中显示出较小的偏差。
使用钛Ti珠作为放射学标记不仅发挥其传统作用，还有效地作为QUS方法的校准目标。这种方法考虑了组织中的衰减和传输损失，从而产生更准确的QUS估计，并为临床环境中增强疾病状态分类提供了一种有前景的方法。
