用AI模型无标记追踪膀胱收缩时的局部形变，更真实反映生理状态。
Quantifying Local Strain Field and Deformation in Active Contraction of Bladder Using a Pretrained Transformer Model: A Speckle-Free Approach
- 基于预训练变压器模型CoTracker3，无需人工标记即可追踪膀胱纹理变化。
- 在4只大鼠膀胱上验证，纵向收缩比环向强（p<0.01），存在显著各向异性。
- 可捕捉复杂折叠形变，适合研究生物组织或工程材料的力学行为。
准确量化膀胱收缩时的局部应变场对理解排尿生物力学至关重要。传统数字图像相关（DIC）方法需人工撒斑，可能改变组织被动与主动特性。本研究提出一种无斑点框架，采用先进零样本变换器模型CoTracker3，结合定制便携式等张双轴装置与多光子显微镜（MPM），成功追踪膀胱腔自然纹理，无需人工标记。基准测试表明该方法具有高像素精度与低应变误差。该框架有效捕捉了复杂褶皱与屈曲下的非均质变形，而传统DIC常失效。在四只大鼠标本（n=4）的体外主动收缩中，发现纵向收缩显著强于环向（p<0.01），呈现统计学显著各向异性；多光子显微镜进一步证实了主动收缩期间的大规模褶皱形成。此非侵入性方法消除了斑点引入的伪影，实现更生理相关的测量，适用于其他生物及工程系统的材料测试。
原文摘要 · Abstract (English)
Accurate quantification of local strain fields during bladder contraction is essential for understanding the biomechanics of bladder micturition, in both health and disease. Conventional digital image correlation (DIC) methods have been successfully applied to various biological tissues; however, this approach requires artificial speckling, which can alter both passive and active properties of the tissue. In this study, we introduce a speckle-free framework for quantifying local strain fields using a state-of-the-art, zero-shot transformer model, CoTracker3. We utilized a custom-designed, portable isotonic biaxial apparatus compatible with multiphoton microscopy (MPM) to demonstrate this approach, successfully tracking natural bladder lumen textures without artificial markers. Benchmark tests validated the method's high pixel accuracy and low strain errors. Our framework effectively captured heterogeneous deformation patterns, despite complex folding and buckling, which conventional DIC often fails to track. Application to in vitro active bladder contractions in four rat specimens (n=4) revealed statistically significant anisotropy (p<0.01), with higher contraction longitudinally compared to circumferentially. Multiphoton microscopy further illustrated and confirmed heterogeneous morphological changes, such as large fold formation during active contraction. This non-invasive approach eliminates speckle-induced artifacts, enabling more physiologically relevant measurements, and has broad applicability for material testing of other biological and engineered systems.
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