Wang Xueding, Xie Xueyi, Ku Geng, Wang Lihong V, Stoica George
Texas A&M University, Department of Biomedical Engineering, Optical Imaging Laboratory, 3120 TAMU, College Station, Texas 77843-3120, USA.
J Biomed Opt. 2006 Mar-Apr;11(2):024015. doi: 10.1117/1.2192804.
Simultaneous transcranial imaging of two functional parameters, the total concentration of hemoglobin and the hemoglobin oxygen saturation, in the rat brain in vivo is realized noninvasively using laser-based photoacoustic tomography (PAT). As in optical diffusion spectroscopy, PAT can assess the optical absorption of endogenous chromophores, e.g., oxygenated and deoxygenated hemoglobins, at multiple optical wavelengths. However, PAT can provide high spatial resolution because its resolution is diffraction-limited by photoacoustic signals rather than by optical diffusion. Laser pulses at two wavelengths are used sequentially to acquire photoacoustic images of the vasculature in the cerebral cortex of a rat brain through the intact skin and skull. The distributions of blood volume and blood oxygenation in the cerebral cortical venous vessels, altered by systemic physiological modulations including hyperoxia, normoxia, and hypoxia, are visualized successfully with satisfactory spatial resolution. This technique, with its prominent sensitivity to endogenous contrast, can potentially contribute to the understanding of the interrelationship between neural, hemodynamic, and metabolic activities in the brain.
利用基于激光的光声断层扫描（PAT），可在体对大鼠脑内两个功能参数——血红蛋白总浓度和血红蛋白氧饱和度进行同步无创经颅成像。与光扩散光谱法一样，PAT能够在多个光学波长下评估内源性发色团（如氧合血红蛋白和脱氧血红蛋白）的光吸收。然而，PAT能够提供高空间分辨率，因为其分辨率受光声信号的衍射限制，而非光扩散限制。通过完整的皮肤和颅骨，依次使用两个波长的激光脉冲来获取大鼠脑皮质血管的光声图像。通过包括高氧、常氧和低氧在内的全身生理调节改变的脑皮质静脉血管中的血容量和血氧分布，以令人满意的空间分辨率成功可视化。这项对内源性对比度具有显著敏感性的技术，可能有助于理解大脑中神经、血流动力学和代谢活动之间的相互关系。
