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We provide herein a detailed description of the experimental protocol for imaging with a newly developed hand-held optoacoustic (photoacoustic) system for three-dimensional functional and molecular imaging in real time. The demonstrated powerful performance and versatility may define new application areas of the optoacoustic technology in preclinical research and clinical practice.
The exclusive combination of high optical contrast and excellent spatial resolution makes optoacoustics (photoacoustics) ideal for simultaneously attaining anatomical, functional and molecular contrast in deep optically opaque tissues. While enormous potential has been recently demonstrated in the application of optoacoustics for small animal research, vast efforts have also been undertaken in translating this imaging technology into clinical practice. We present here a newly developed optoacoustic tomography approach capable of delivering high resolution and spectrally enriched volumetric images of tissue morphology and function in real time. A detailed description of the experimental protocol for operating with the imaging system in both hand-held and stationary modes is provided and showcased for different potential scenarios involving functional and molecular studies in murine models and humans. The possibility for real time visualization in three dimensions along with the versatile handheld design of the imaging probe make the newly developed approach unique among the pantheon of imaging modalities used in today’s preclinical research and clinical practice.
光声(光声)成像每年吸引从生物和医学研究界日益增长的兴趣,这表现在数量不断增加的出版物涵盖各种各样的利用由技术1-5所提供的独特优点的新的应用程序。特别是,能力与在深度远远超出光的扩散极限高时空分辨率的图像进行频谱独特的光吸收剂打开前所未有的功能,用于功能和分子成像6-10。
事实上,光声技术应用到临床实践中译本自带的诊断和许多疾病的治疗监测前景十分广阔。然而,在光散射光子吸收的组织和与光声现象相关联的通常弱响应的有限传播限制了该方法的适用的深度。其结果是,手持optoacoustic探针已试图从本体11,12的外部接近的图像部分,而内窥镜系统所使用的通过自然孔口13插入它们提供从身体内的图像。一些低吸收人体的部位,如女性的乳房,并且也是由断层光声扫描仪14,15进行访问。特别令人感兴趣的是手持式的办法,因为它使大量的通用性,类似于超声。在这里,普通超声线阵探头,光声成像的改编依然充满挑战,主要是由于超声波和optoacoustics之间的断层成像要求根本性的分歧。而在标准超声高帧率被顺序使能发送接收计划采用在kHz范围内的高的脉冲重复频率,实时三维光声成像是通过同时采集的容积断层数据从单个int实现errogating激光脉冲。因此,高品质的光声成像意味着采集的三维数据从成象物体周围尽可能大的立体角。
最近,我们推出了第一台手持式光声探测三维(立体)影像实时16。该系统是基于二维的排列后的球面(蓝点在图1A中)256压电元件覆盖90°的角度阵列上。约为3×3 平方毫米的各个元件的尺寸,以及它们的取向和频率带宽(约2-6兆赫)从围绕球体的中心(黑立方体图一厘米刻度体积保证有效信号采集1A)。摄像区域的光激发设置有通过所述阵列的中央圆柱形腔插入的纤维束,以使任何波长SUSC通过对纤维束被传输的eptible可用于成像。换能器的阵列沿与光纤束的实际图像显示在图1B中 。有效激发并同时检测信号允许深层组织成像单次激励(1激光脉冲),从而在通过激光的脉冲重复频率确定的帧速率实时成像进一步与一个图形 - 启用处理单元(GPU)执行重建程序17。一个圆筒形壳体具有一个透明聚乙烯膜( 图1C)连接到所述换能器阵列,以围成一个声学传输液体介质(水)。该膜进一步耦合到所述组织通过声凝胶的装置。的光声探测器作为手持操作模式下使用的一个图象被显示在图1D中 。
该证明THRee值维手持式光声成像结合实时功能成像能力来与对临床诊断和一些潜在应用的重要优点可以设想的各种迹象,如外周血管病,淋巴系统疾病,乳腺癌,皮肤损害,炎或关节炎18。此外,快速成像能力使与设置在一个固定的位置上的探头动态生物事件的可视化。结合快速波长调谐光学参量振荡器(OPO)激光技术,该方法允许光吸收剂的生物分布的实时成像。因此,新的可能性,可能会同样出现在小动物成像应用, 例如 ,在学习组织的血流动力学, 体内细胞跟踪,药代动力学,器官灌注可视化,有针对性的肿瘤和心血管系统,神经影像学或分子成像。
在此工作中,我们提供了实验成像协议的详细描述与在几个典型的临床和小动物成像场景中的球形阵列光声手持式探头和陈列柜的性能操作。
对于与体积手持光声探测器操作的详细过程描述如下。此过程是根据关于动物和人体试验批准机构法规进行。
1.系统准备
2.影像学准备
3.预视图操作模式
4.数据采集
5.最后确定实验
6.离线数据处理
代表性的结果,显示了所描述的容积手持式光声探测器的功能,是展示在本节。在所有情况下,光积分通量在皮肤表面上保持在低于20毫焦/厘米2 19中的安全性的暴露极限。
探针在实时跟踪外围人脉管系统的性能被展示在图2中,在此实验的过程中,所述探针缓慢地沿着健康人类志愿者的手,在800纳米的激光器工作在单波长扫描以每秒17 10个脉冲,?...
通过光声成像技术在小动物的研究提供了独特的优势创造了强大的动力转换的技术应用到临床实践中,有许多诊断和设想如治疗监测的应用。在乳腺癌和皮肤癌,炎症或外周血管疾病。然而,相对于小鼠或更小的动物,其可通过照射源和检测元件的足够数量的被包围,以创建一个有效的断层图像采集几何结构,对人体和限量光学穿透阻碍实现全身的大尺寸光声断层成像类似于MRI或CT检查。?...
The authors have nothing to disclose.
The research leading to these results has received funding from the European Research Council under grant agreement ERC-2010-StG-260991.
Name | Company | Catalog Number | Comments |
Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
Optical parametric oscillator (OPO)-based laser | Innolas Laser GmbH, Krailling (Germany) | custom-made | The laser provides laser pulses with a duration around 10ns and an energy up to 80mJ. The wavelength is tunable between 680-950nm. |
Spherical array of piezocomposite detectors | Imasonic SaS, Voray (France) | custom-made | The array consists of 256 piezoelectric sensors distributed on a spherical surface. Each element has dimensions 3x3mm2, a central frequency of 4MHz and a bandwidth of 100%. |
Data acquisition system (DAQ) | Falkenstein Mikrosysteme GmbH, Taufkirchen (Germany) | custom-made | The DAQ simultaneously acquires 256 signals at 40 megasamples per second and 2030 samples. The input impedance is 1MW. |
Fiber bundle | CeramOptec GmbH, Bonn (Germany) | custom-made | The bundle consists of 480 individual fibers randomly distributed in the input and output. The numerical aperture of each individual fiber is 0.22. |
Athymic Nude mouse | Harlan Laboratories (The Netherlands) | Athymic nude - Foxn1nu | The mouse was 8 weeks old (adult) at the time of the experiment. The ethical protocol was approved by the Bavarian goverment (number 55.2.1.54-2632-102-11) |
Bepanthen cream | Bayer AG (Germany) | N/A | Vet ointment to protect the eyes during anesthesia |
Data processing software | Matlab (Mathworks, Natick, MA, USA) | custom-made | The data processing software was devoped at our institute. It allows reconstruction at each wavelength and multi-wavelength unmixing, as well as further data processing. |
Water-enclosing part | N/A | custom-made | This part contains the water that acts as an acoustic coupling medium between skin and transducer elements |
Indocyanine green (ICG) | PULSION Medical Systems SE | N/A | ICG-PULSION (active ingredient: indocyanine green dye) is a drug used in cardiac, circulatory and micro-circulatory diagnostics, liver function diagnostics and ophthalmic angiography diagnostics. |
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