Biophotonics: Acousto-optic Elastography

0086719 Kirkpatrick众所周知，病理组织的机械性能不同于健康组织。 例如，许多疾病过程，如乳腺和前列腺的肿瘤，表现为相对于周围组织的坚硬结节。 皮下皮肤肿瘤表现为相对于周围正常组织具有不同机械特性的物体。 纤维状乳头状真皮被生长中的黑色素瘤的较软的细胞团所取代就是这样一个例子。 这一特征经常允许通过手动触诊来检测它们。 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，它提供了相当大的空间尺度上的信息，因此通过触诊检测小肿瘤的能力有限。 与其他弹性成像方法相比，声光弹性成像（AOE）具有提高空间分辨率（即可以检测到较小的病变）和更好的应变分辨率（可以显示低对比度弹性模量分布）的潜力。 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，光学弹性成像是有限的，因为在任何一个时间只能探测相对小的组织区域或体积。 尽管如此，光学方法在肿瘤变化的早期检测中仍然是有用的，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。 在这项提案中，研究人员的目标是实施一种新的声光方法来评估组织的机械性能。 该方法，结合了一种新的光纤耦合激光散斑应变计，提供高分辨率的应变和应变率测量组织进行加载或蠕变恢复后加载。 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。 使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硬度的组织区域。 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的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.