Biophotonics: Acousto-optic Elastography

[86719]众所周知，病理组织的力学特性与健康组织不同。例如，许多疾病过程，如乳腺和前列腺肿瘤，表现为相对于周围组织的僵硬、坚硬的结节。相对于周围的正常组织，皮下肿瘤表现为具有不同力学特性的物体。纤维状乳头状真皮被生长中的黑色素瘤中较软的细胞团块所取代就是这样一个例子。这个功能通常允许通过手动触诊检测它们。然而，标准的软组织触诊不仅是定性的，而且是高度主观的。此外，它提供的信息在相当大的空间尺度上，因此通过触诊检测小肿瘤的能力是有限的。声光弹性成像（AOE）提供了比其他弹性成像方法更高的空间分辨率（即可以检测到更小的病变）和更好的应变分辨率（可以可视化低对比度弹性模量分布）。然而，这种增加的空间和应变分辨率是以降低探测深度为代价的，因为光学方法仅限于组织的外部几毫米。此外，光学弹性成像的局限性在于每次只能探测相对较小的组织区域或体积。尽管如此，光学方法仍然可以用于早期发现肿瘤变化，因为许多这些早期变化发生在受影响器官的粘膜和粘膜下层。在这项提议中，研究人员的目标是实现一种新的声光方法来评估组织的力学性能。该方法结合了一种新型的光纤耦合激光散斑应变计，可在加载或加载后蠕变恢复的组织中提供高分辨率应变和应变率测量。这些数据可用于量化具有不同刚度的组织区域，用于诊断目的和基础组织力学研究。利用图像和信号处理技术，可以从这些图像中描绘出显示不同组织刚度的组织区域。最终目标是这些图像可以为临床医生提供关于被检查组织病理状态的直接信息。

0086719KirkpatrickIt is well known that the mechanical properties of pathological tissues vary from that of healthy tissue. For example, many disease processes such as tumors of the breast and prostate manifest themselves as stiff, hard nodules relative to the surrounding tissue. Subsurface skin tumors present themselves as objects with distinct mechanical properties relative to the surrounding normal tissue. The displacement of fibrillar papillary dermis by the softer, cellular mass of a growing melanoma is one such example of this. This feature frequently allows their detection through manual palpation. However, standard soft tissue palpation is not only qualitative, but also highly subjective. Furthermore, it provides information on a rather large spatial scale, thus the ability to detect small tumors by palpation is limited. Acousto-optic elastrography (AOE) offers the potential for increased spatial resolution (i.e. smaller lesions may be detected) and better strain resolution (low-contrast elastic modulus distributions may be visualized) than other elastographic methods. However, this increased spatial and strain resolution is gained a the cost of decreased probing depth, as optical methods are limited to the outer few millimeters of tissue. Furthermore, optical elastography is limited in that only relatively small areas or volumes of tissues may be probed at any one time. Never the less, optical methods can still be useful in the early detection of neoplastic changes because many of these early changes occur in the mucosa and submucosa of the affected organs. In this proposal, the investigators aim to implement a novel, acousto-optical method for evaluation tissue mechanical properties. The method, incorporating a novel fiber-coupled laser speckle strain gauge, provides high resolution strain and strain rate measurements in tissues undergoing loading or undergoing creep recovery following loading. These data can be used to quantify tissue regions with differential stiffness for both diagnostic purposes and for basic tissue mechanics research. Using image and signal processing techniques, tissue regions which display differential tissue stiffnesses can be delineated from these images. The end goal is that these images can provide the clinician direct information regarding the pathological state of the tissue under examination.