Endoscopic photoacoustic devices for minimally invasive biomedical sensing and imaging

该项目的目的是开发一系列用于微创临床应用的微型内窥镜光声探头，例如检测食管或结肠等器官中的癌症，冠状动脉疾病的血管内评估或指导介入手术，如硬膜外注射或锁孔手术。光声成像是一种利用短脉冲激光吸收产生的超声波对生物组织进行可视化的新技术。在过去的5年中，光声技术的巨大进步引起了人们极大的兴趣，这主要是由于最近几个研究小组获得了精美的组织活体图像。迄今为止，大多数努力都集中在开发用于乳腺癌和皮肤癌成像等应用的非侵入性成像仪器上。相比之下，较少关注微创应用，其中将微型光纤探针插入体内以接近感兴趣的器官或组织。这部分是由于与使用压电检测器制造微型光声探针相关联的技术挑战，压电检测器常规地用于检测光声信号。我们建议通过开发一系列微型内窥镜设备来解决这个问题，这些设备使用基于法布里-珀罗聚合物膜标准具的新型光学超声传感器。这种方法在尺寸、成本和性能方面具有显著的优势。因为传感器是使用薄膜真空沉积技术形成的并且是光学透明的，所以它可以直接沉积在用于将激发激光能量传递到目标组织的非常细的光纤的尖端上。这提供了制造比使用传统压电探测器可能的小得多的探针的前景，可能小到一根人的头发。它还允许以相对较低的单位成本批量制造-这是一个重要的要求，因为许多微创应用需要一次性设备。此外，传感器可以容易地沉积在各种光纤尖端几何形状（单光纤、角度抛光或成形的光纤尖端、光纤束等）上，从而允许实现多种感测和成像设备（前视、侧视、单个或多个元件）。也许最重要的是，我们已经表明，这种类型的传感器提供了非常高的宽带灵敏度，使前所未有的质量的光声图像被obtained.These优势将被利用开发一系列新颖的内窥镜设备：一个单一的元素前视探头，侧视探头和多元素成像探头。将进行体内动物研究，以证明该技术在评估食管癌和冠状动脉疾病以及用于输送麻醉的引导针方面的应用。这些应用不仅在临床上具有重要意义，而且还将说明该技术在介入医学的许多其他分支中具有更广泛的潜力。例如，这些探头还可以潜在地用于下胃肠道、诸如前列腺和肝脏的实体器官的成像以及引导针活检、导管消融治疗、腹腔镜手术和其他介入手术。为了开展该项目，组建了一个多学科研究小组。这包括医学物理学家和生物工程师，他们在光声成像、声学建模和医疗设备工程方面具有重要的专业知识，以及具有将新设备和光学技术转化为临床实践经验的临床医生。如果成功，这项研究可以开辟光声技术的许多新应用，从而改善癌症和其他疾病的诊断和治疗，并降低介入手术期间并发症的风险。

The aim of this project is to develop a range of miniature endoscopic photoacoustic probes for minimally invasive clinical applications such as the detection of cancers in organs such as the oesophagus or colon, the intravascular assessment of coronary artery disease or guiding interventional procedures such as epidural injections or key-hole surgery. Photoacoustic imaging is a new technique for visualizing biological tissues based on the use of ultrasound waves generated by the absorption of short laser pulses. The tremendous advances in photoacoustic techniques over the last 5 years have excited significant interest, largely due to the exquisite in vivo images of tissues that have recently been obtained by several research groups. To date, most efforts have been focused on developing non invasive imaging instruments for applications such as breast and skin cancer imaging. By contrast, less attention has been devoted to minimally invasive applications where a miniature fibre optic probe is inserted into the body in order to access the organ or tissue of interest. This is in part due to the technical challenges associated with fabricating miniature photoacoustic probes using piezoelectric detectors which are conventionally used to detect photoacoustic signals. We propose to address this by developing a range of miniature endoscopic devices that use a novel optical ultrasound sensor based upon a Fabry Perot polymer film etalon. This approach offers significant advantages in terms of size, cost and performance. Because the sensor is formed using thin film vacuum deposition techniques and is optically transparent, it can be directly deposited on to the tip of a very fine optical fibre which is used to deliver the excitation laser energy to the target tissue. This offers the prospect of fabricating much smaller probes than possible using conventional piezoelectric detectors, potentially as small as a single human hair. It also permits batch fabrication at relatively low unit cost - an important requirement as many minimally invasive applications require disposable devices. In addition the sensor can readily be deposited on to a variety of fibre tip geometries (single fibres, angle polished or shaped fibre tips, fibre bundles etc) allowing a diversity of sensing and imaging devices (forward-viewing, side-viewing, single or multi-element) to be realised. Perhaps most importantly, we have shown that this type of sensor provides very high wideband sensitivity enabling photoacoustic images of unprecedented quality to be obtained.These advantages will be exploited to develop a range of novel endoscopic devices: a single element forward-viewing probe, a side-viewing probe and multielement imaging probes. In vivo animal studies will be undertaken to demonstrate the application of the technology to the assessment of oesophageal cancer and coronary artery disease and guiding needles used to deliver anaesthesia. As well as being clinically important themselves, these applications will serve to illustrate the broader potential of the technology in many other branches of interventional medicine. For example, these probes could potentially also be used for imaging the lower gastrointestinal tract, solid organs such as the prostate and liver and guiding needle biopsies, catheter ablation treatments, laparoscopic surgery and other interventional procedures. To undertake the project a multidisciplinary research team has been assembled. This comprises medical physicists and bioengineers with significant expertise in photoacoustic imaging, acoustic modeling and medical device engineering and clinicians with experience of translating new devices and optical techniques to clinical practice. If successful, this research could open up many new applications of photoacoustic techniques that could lead to improved diagnosis and treatment of cancer and other diseases and reduce the risk of complications during interventional procedures.