Biophotonics: Acousto-optic Elastography

柯克帕特里克众所周知，病理组织的机械性能与健康组织的不同。例如，许多疾病过程，如乳腺癌和前列腺癌，相对于周围组织表现为僵硬的结节。与周围正常组织相比，皮肤下肿瘤表现为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较软的细胞团所取代就是这样的一个例子。该功能通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定性，而且主观性很强。此外，它在相当大的空间尺度上提供信息，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(可以显示低对比度的弹性模数分布)。然而，这种增加的空间和应变分辨率是以减少探测深度的成本获得的，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一次只能探测相对较小的区域或体积的组织。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，因为这些早期变化中的许多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现一种新的声光方法来评估组织的机械特性。该方法结合了一种新型的光纤耦合激光散斑应变仪，可在加载或加载后经历蠕变恢复的组织中提供高分辨率的应变和应变率测量。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有关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.