School of Biomedical Engineering, University of British Columbia, Vancouver, Canada.
Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, Canada; Department of Mechanical Engineering, University of British Columbia, Vancouver, Canada.
Ultrasonics. 2024 Jan;136:107171. doi: 10.1016/j.ultras.2023.107171. Epub 2023 Sep 23.
A flexible ultrasound array can potentially provide a larger field-of-view, enhanced imaging resolution, and less operator dependency compared to conventional rigid transducer arrays. However, such transducer arrays require information about relative element positions for beamforming and reconstructing geometrically accurate sonograms. In this study, we assess the potential utility of using spatial coherence of backscattered radiofrequency data to estimate transducer array shape (inverse problem). The methodology is evaluated through 1) simulation of flexible arrays and 2) blinded in vivo experiments using commercial rigid transducer arrays on various anatomical targets (shoulder, forearm, scapular, posterior calf muscles, and abdomen) and multi-purpose ultrasound phantoms. The average Euclidean error of shape estimation is below 0.1 wavelengths for simulated arrays and below 1.4 wavelengths (median: 0.58 wavelengths) for real arrays. The complex wavelet structural similarity index between the B-mode images reconstructed with estimated and ground truth array shapes is above 99 % and 96 %, for simulations and experiments, respectively. These findings suggest that optimizing for spatial coherence may be an effective way to estimate the unknown shape of conformal ultrasound arrays.
与传统刚性换能器阵列相比，灵活的超声阵列具有潜在的更大视野、更高的成像分辨率和更少的操作人员依赖性。然而，这种换能器阵列需要关于相对元件位置的信息，以便进行波束形成和重建几何精确的超声图像。在这项研究中，我们评估了使用反向散射射频数据的空间相干性来估计换能器阵列形状（反问题）的潜在效用。该方法通过 1）对柔性阵列进行模拟，以及 2）在各种解剖目标（肩部、前臂、肩胛骨、后小腿肌肉和腹部）和多用途超声体模上使用商业刚性换能器阵列进行盲法体内实验进行评估。模拟阵列的形状估计平均欧几里得误差低于 0.1 波长，真实阵列的平均欧几里得误差低于 1.4 波长（中位数：0.58 波长）。模拟和实验中，用估计的和真实的阵列形状重建的 B 模式图像之间的复杂小波结构相似性指数均高于 99%和 96%。这些发现表明，优化空间相干性可能是估计共形超声阵列未知形状的有效方法。
