Innsbruck Medical University, Department of Radiology, Innsbruck, Austria.
J Biomed Opt. 2011 Mar;16(3):036007. doi: 10.1117/1.3556720.
In the present study, we evaluated the applicability of ex vivo photoacoustic imaging (PAI) on small animal organs. We used photoacoustic tomography (PAT) to visualize infarcted areas within murine hearts and compared these data to other imaging techniques [magnetic resonance imaging (MRI), micro-computed tomography] and histological slices. In order to induce ischemia, an in vivo ligation of the left anterior descending artery was performed on nine wild-type mice. After varying survival periods, the hearts were excised and fixed in formaldehyde. Samples were illuminated with nanosecond laser pulses delivered by a Nd:YAG pumped optical parametric oscillator. Ultrasound detection was achieved using a Mach-Zehnder interferometer (MZI) working as an integrating line detector. The voxel data were computed using a Fourier-domain based reconstruction algorithm, followed by inverse Radon transforms. The results clearly showed the capability of PAI to visualize myocardial infarction and to produce three-dimensional images with a spatial resolution of approximately 120 μm. Regions of affected muscle tissue in PAI corresponded well with the results of MRI and histology. Photoacoustic tomography utilizing a MZI for ultrasound detection allows for imaging of small tissue samples. Due to its high spatial resolution, good soft tissue contrast and comparatively low cost, PAT offers great potentials for imaging.
在本研究中，我们评估了离体光声成像（PAI）在小动物器官上的适用性。我们使用光声断层扫描（PAT）可视化小鼠心脏内的梗塞区域，并将这些数据与其他成像技术（磁共振成像（MRI）、微计算机断层扫描）和组织切片进行比较。为了诱导缺血，在 9 只野生型小鼠上进行了活体左前降支结扎。在不同的存活期后，取出心脏并用甲醛固定。用纳秒激光脉冲照射样品，由 Nd:YAG 泵浦光参量振荡器提供。使用马赫-曾德尔干涉仪（MZI）作为积分线探测器实现超声检测。体素数据使用基于傅里叶域的重建算法计算，然后进行逆拉东变换。结果清楚地表明了 PAI 可视化心肌梗塞和产生具有约 120μm 空间分辨率的三维图像的能力。PAI 中受影响的肌肉组织区域与 MRI 和组织学结果非常吻合。利用 MZI 进行超声检测的光声断层扫描允许对小组织样本进行成像。由于其具有高空间分辨率、良好的软组织对比度和相对较低的成本，PAT 为成像提供了巨大的潜力。
