Metzner Kai L, Fang Qi, Sanderson Rowan W, Mowla Alireza, Kennedy Brendan F
BRITElab, Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, and Centre for Medical Research, The University of Western Australia, Perth, WA 6009, Australia.
Department of Electrical, Electronic & Computer Engineering, School of Engineering, The University of Western Australia, Perth, WA 6009, Australia.
Biomed Opt Express. 2023 Sep 11;14(10):5127-5147. doi: 10.1364/BOE.494013. eCollection 2023 Oct 1.
Quantitative micro-elastography (QME) is a compression-based optical coherence elastography technique capable of measuring the mechanical properties of tissue on the micro-scale. As QME requires contact between the imaging window and the sample, the presence of friction affects the accuracy of the estimated elasticity. In previous implementations, a lubricant was applied at the contact surfaces, which was assumed to result in negligible friction. However, recently, errors in the estimation of elasticity caused by friction have been reported. This effect has yet to be characterized and is, therefore, not well understood. In this work, we present a systematic analysis of friction in QME using silicone phantoms. We demonstrate that friction, and, therefore, the elasticity accuracy, is influenced by several experimental factors, including the viscosity of the lubricant, the mechanical contrast between the compliant layer and the sample, and the time after the application of a compressive strain. Elasticity errors over an order of magnitude were observed in the absence of appropriate lubrication when compared to uniaxial compression testing. Using an optimized lubrication protocol, we demonstrate accurate elasticity estimation (<10% error) for nonlinear elastic samples with Young's moduli ranging from 3 kPa to 130 kPa. Finally, using a structured phantom, we demonstrate that friction can significantly reduce mechanical contrast in QME. We believe that the framework established in this study will facilitate more robust elasticity estimations in QME, as well as being readily adapted to understand the effects of friction in other contact elastography techniques.
定量微弹性成像（QME）是一种基于压缩的光学相干弹性成像技术，能够在微观尺度上测量组织的力学性能。由于QME需要成像窗口与样品之间进行接触，摩擦力的存在会影响弹性估计的准确性。在以前的实施方案中，在接触表面涂抹润滑剂，假定其产生的摩擦力可忽略不计。然而，最近有报道称摩擦力会导致弹性估计出现误差。这种效应尚未得到表征，因此人们对此了解不足。在这项工作中，我们使用硅胶体模对QME中的摩擦力进行了系统分析。我们证明，摩擦力进而弹性准确性会受到几个实验因素的影响，包括润滑剂的粘度、柔顺层与样品之间的力学对比度以及施加压缩应变后的时间。与单轴压缩测试相比，在没有适当润滑的情况下观察到弹性误差超过一个数量级。通过使用优化的润滑方案，我们证明了对于杨氏模量范围为3 kPa至130 kPa的非线性弹性样品，能够进行准确的弹性估计（误差<10%）。最后，使用结构化体模，我们证明摩擦力会显著降低QME中的力学对比度。我们相信，本研究建立的框架将有助于在QME中进行更可靠的弹性估计，并且易于应用于理解其他接触式弹性成像技术中摩擦力的影响。
