Improved right ventricular strain estimation in rats using anisotropic diffusion filtering.
Improved right ventricular strain estimation in rats using anisotropic diffusion filtering.
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使用各向异性扩散过滤改进大鼠右心室应变估计。
DOI：
10.1117/12.2654100
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Avazmohammadi,Reza
中科院分区：
文献类型：
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作者：
Mukherjee,Tanmay;Neelakantan,Sunder;Choudhary,Gaurav;Avazmohammadi,Reza
通过斑点追踪超声心动图（STE）计算心脏应变已显示出作为与功能指数和疾病结局相关的预后标志物的前景。然而，声阴影的存在往往挑战了STE在啮齿动物等小动物中的准确性。阴影的出现是由于啮齿动物的复杂解剖结构，操作者的灵活性在图像质量中起着重要作用。由于右心室自由壁（RVFW）的薄和快速运动，半透明阴影的影响在右心室（RV）成像中进一步加剧。RVFW在阴影中的移动会扭曲斑点跟踪，并产生不自然和非物理的应变。本研究的目的是通过区分“出阴影”运动和识别阴影内外的斑点来最大限度地减少阴影对STE的影响。进行胸骨旁2D超声心动图检查，并采集啮齿动物肺动脉高压模型（n = 1）的RVFW短轴B型（SA）图像。在图像采集之后，使用边缘增强各向异性扩散（EED）实现去噪算法，并且使用定制的STE流水线可视化随后对应变分析的影响。通过滤波图像和原始采集之间的相关性识别阴影区域中的散斑。因此，通过增强阴影和心脏壁之间的区别来识别跨越边界的像素移动，并且抑制非物理应变。通过STE获得的应变显示出预期的模式，与来自未处理图像的较小且几乎均匀的应变相比，RVFW中心区域的周向收缩增强。
Calculating cardiac strains through speckle tracking echocardiography (STE) has shown promise as prognostic markers linked to functional indices and disease outcomes. However, the presence of acoustic shadowing often challenges the accuracy of STE in small animals such as rodents. The shadowing arises due to the complex anatomy of rodents, with operator dexterity playing a significant role in image quality. The effects of the semi-transparent shadows are further exacerbated in right ventricular (RV) imaging due to the thinness and rapid motion of the RV free wall (RVFW). The movement of the RVFW across the shadows distorts speckle tracking and produces unnatural and non-physical strains. The objective of this study was to minimize the effects of shadowing on STE by distinguishing “out-of-shadow” motion and identifying speckles in and out of shadow. Parasternal 2D echocardiography was performed, and short-axis B-mode (SA) images of the RVFW were acquired for a rodent model of pulmonary hypertension (n = 1). Following image acquisition, a denoising algorithm using edge-enhancing anisotropic diffusion (EED) was implemented, and the ensuing effects on strain analysis were visualized using a custom STE pipeline. Speckles in the shadowed regions were identified through a correlation between the filtered image and the original acquisition. Thus, pixel movement across the boundary was identified by enhancing the distinction between the shadows and the cardiac wall, and non-physical strains were suppressed. The strains obtained through STE showed expected patterns with enhanced circumferential contractions in the central region of the RVFW in contrast to smaller and nearly uniform strains derived from the unprocessed images.