Carvalho Catarina, Slagmolen Pieter, Bogaerts Stijn, Scheys Lennart, D'hooge Jan, Peers Koen, Maes Frederik, Suetens Paul
1 Katholieke Universiteit Leuven, ESAT-PSI, Leuven, Belgium.
2 Materialise Group, Leuven, Belgium.
Ultrason Imaging. 2018 Mar;40(2):67-83. doi: 10.1177/0161734617724658. Epub 2017 Aug 23.
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.
用于肌腱病评估的肌腱应变估计是运动医学领域的一个热门话题。人们认为，如果能够准确估计，现有的治疗和康复方案可以得到改进，并且可以更早地检测出症状前的异常情况。目前的前沿研究给出的应变估计不准确且变化很大，这个问题仍然没有解决方案。在获取二维（2D）超声（US）图像时出现的平面外运动是一个已知问题，可能是导致此类误差的原因。这项工作研究了高频三维（3D）超声成像在减少肌腱应变估计误差方面的益处。使用一种创新的采集方法，将二维高频超声图像的采集与机械引导系统相结合，在计算机模拟、体外和离体条件下采集了容积式超声图像。采用仿射图像配准方法估计全局应变。然后将三维应变估计值与真实值以及二维应变估计值进行比较。计算机模拟数据的结果显示，三维估计在轴向、横向和仰角方向的平均绝对误差（MAE）分别为0.07%、0.05%和0.27%，二维应变估计的MAE分别为0.21%和0.29%。虽然三维可能优于二维，但在体外和离体环境中并非如此，这可能是由于三维采集伪像所致。与现有方法的比较显示出具有竞争力的结果。所提出的工作表明，三维应变估计比二维估计更准确，但获取合适的三维超声图像仍然是一个挑战。
