KU Leuven Department of Mechanical Engineering, Celestijnenlaan 300b, 3001 Leuven, Belgium; Clinical Motion Analysis Laboratory, University Hospital Leuven, Weligerveld 1, 3212 Pellenberg, Belgium.
Clinical Motion Analysis Laboratory, University Hospital Leuven, Weligerveld 1, 3212 Pellenberg, Belgium; KU Leuven Department of Rehabilitation Sciences, Tervuursevest 101, 3001 Leuven, Belgium.
J Biomech. 2018 Aug 22;77:194-200. doi: 10.1016/j.jbiomech.2018.06.002. Epub 2018 Jun 18.
3D freehand ultrasound enables the creation of volumetric data. The acquisition of morphological features, such as muscle volume, is influenced by the variations in force applied to the skin with the ultrasound probe. To minimise the deformations, a concave-shaped plastic mount combined with a custom-shaped gel pad was developed for the ultrasound head, named Portico. This study analyses to what extent the Portico reduces muscle deformation and corresponding errors in estimating muscle volume.
Twenty medial gastrocnemius (MG) muscles were assessed (10 from typically developing children; 10 from children with spastic cerebral palsy). Two repetitions were acquired in each of the following approaches: (1) with the lower leg submerged in a water tank as a non-deformed reference; (2) probe-on-skin (PoS) as the conventional approach and (3) the newly introduced Portico. PoS and Portico data were registered with respect to the ones corresponding in a water tank. An in-house software package (Py3DFreeHandUS) was used to process the data and MG volume was estimated using MeVisLab. The minimal detectable change (MDC) was calculated.
With respect to the PoS approach, the Portico reduced muscle deformation by 46%. For both the typically developing and spastic cerebral palsy cohorts, lower MDCs were found when using the Portico.
Despite the improvements, the Portico did not yield statistically more reliable MG volume estimations than the traditional PoS approach. Further improvement can be attained by optimising the fit between the gel pad and the curvature of the limb, using a larger choice of Portico geometries.
3D 自由式超声能创建容积数据。形态特征（如肌肉体积）的采集会受到超声探头施加在皮肤上的力的变化影响。为了尽量减少变形，我们为超声探头设计了一种凹形塑料座和定制凝胶垫的组合，名为 Portico。本研究分析了 Portico 在多大程度上减少了肌肉变形和相应的肌肉体积估计误差。
评估了 20 个内侧腓肠肌（MG）（10 个来自正常发育儿童；10 个来自痉挛性脑瘫儿童）。分别采用以下三种方法进行两次重复采集：（1）小腿浸在水箱中作为无变形参考；（2）探头接触皮肤（PoS），为传统方法；（3）新引入的 Portico。PoS 和 Portico 数据相对于水箱中相应的数据进行了注册。使用内部软件包（Py3DFreeHandUS）来处理数据，并使用 MeVisLab 估计 MG 体积。计算了最小可检测变化（MDC）。
与 PoS 方法相比，Portico 减少了 46%的肌肉变形。对于正常发育和痉挛性脑瘫两组，使用 Portico 时 MDC 更低。
尽管有所改进，但 Portico 并没有比传统的 PoS 方法提供更可靠的 MG 体积估计。通过优化凝胶垫与肢体曲率之间的适配性，使用更多种类的 Portico 几何形状，可以进一步提高其性能。
