Shao Qi, Ashkenazi Shai
J Biomed Opt. 2015 Mar;20(3):036004. doi: 10.1117/1.JBO.20.3.036004.
Measuring the partial pressure of oxygen (pO₂) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO₂ have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO₂ and recovery from hypoxia due to reperfusion were tracked and observed by PALI.
测量组织中的氧分压（pO₂）可为医生提供有关组织生理状态的重要信息。然而，目前可用的测量或成像组织pO₂的方法存在显著局限性，阻碍了它们在临床上的广泛应用。最近，我们报道了一种基于光声寿命的直接且无创的体内成像方式，它克服了现有方法的某些缺点。该技术绘制对氧敏感染料的激发三重态图谱，从而反映组织氧的时空分布。在此，我们展示两项研究，它们应用光声寿命成像（PALI）来监测外部调节引起的组织氧变化。第一项研究通过控制正常小鼠吸入的氧气百分比来调节组织氧。我们证明PALI能够反映正常、富氧和缺氧呼吸条件下的氧水平变化。第二项研究涉及一个急性缺血模型，使用细线结扎正常小鼠的后肢以减少血流。在限制血流之前、期间和之后采集PALI图像。通过PALI跟踪并观察到组织pO₂的下降以及再灌注导致的缺氧恢复情况。
