Estimation of strain in tendons for tendinopathy assessment is a hot topic within the sports medicine community. It is believed that, if accurately estimated, existing treatment and rehabilitation protocols can be improved and presymptomatic abnormalities can be detected earlier. State-of-the-art studies present inaccurate and highly variable strain estimates, leaving this problem without solution. Out-of-plane motion, present when acquiring two-dimensional (2D) ultrasound (US) images, is a known problem and may be responsible for such errors. This work investigates the benefit of high-frequency, three-dimensional (3D) US imaging to reduce errors in tendon strain estimation. Volumetric US images were acquired in silico, in vitro, and ex vivo using an innovative acquisition approach that combines the acquisition of 2D high-frequency US images with a mechanical guided system. An affine image registration method was used to estimate global strain. 3D strain estimates were then compared with ground-truth values and with 2D strain estimates. The obtained results for in silico data showed a mean absolute error (MAE) of 0.07%, 0.05%, and 0.27% for 3D estimates along axial, lateral direction, and elevation direction and a respective MAE of 0.21% and 0.29% for 2D strain estimates. Although 3D could outperform 2D, this does not occur in in vitro and ex vivo settings, likely due to 3D acquisition artifacts. Comparison against the state-of-the-art methods showed competitive results. The proposed work shows that 3D strain estimates are more accurate than 2D estimates but acquisition of appropriate 3D US images remains a challenge.

中文翻译：

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使用高频体积超声图像进行 3D 肌腱应变估计：可行性研究

用于肌腱病变评估的肌腱应变估计是运动医学界的一个热门话题。人们相信，如果准确估计，可以改进现有的治疗和康复方案，并且可以更早地检测到症状前异常。最先进的研究提出了不准确和高度可变的应变估计，使这个问题无法解决。获取二维 (2D) 超声 (US) 图像时出现的平面外运动是一个已知问题，可能是造成此类错误的原因。这项工作调查了高频、三维 (3D) 超声成像在减少肌腱应变估计中的错误的好处。体积 US 图像是在硅片、体外、和离体使用创新的采集方法，将 2D 高频 US 图像的采集与机械引导系统相结合。仿射图像配准方法用于估计全局应变。然后将 3D 应变估计值与真实值和 2D 应变估计值进行比较。获得的计算机数据结果显示，沿轴向、横向和高度方向的 3D 估计的平均绝对误差 (MAE) 为 0.07%、0.05% 和 0.27%，而 2D 应变的平均绝对误差 (MAE) 分别为 0.21% 和 0.29%估计。虽然 3D 可能优于 2D，但这不会发生在体外和离体环境中，这可能是由于 3D 采集伪影。与最先进方法的比较显示出具有竞争力的结果。