Laboratory for Accelerated Vascular Research, Division of Vascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California, United States of America.
PLoS One. 2012;7(6):e38590. doi: 10.1371/journal.pone.0038590. Epub 2012 Jun 26.
The ability to measure blood velocities is critical for studying vascular development, physiology, and pathology. A key challenge is to quantify a wide range of blood velocities in vessels deep within living specimens with concurrent diffraction-limited resolution imaging of vascular cells. Two-photon laser scanning microscopy (TPLSM) has shown tremendous promise in analyzing blood velocities hundreds of micrometers deep in animals with cellular resolution. However, current analysis of TPLSM-based data is limited to the lower range of blood velocities and is not adequate to study faster velocities in many normal or disease conditions.
METHODOLOGY/PRINCIPAL FINDINGS: We developed line-scanning particle image velocimetry (LS-PIV), which used TPLSM data to quantify peak blood velocities up to 84 mm/s in live mice harboring brain arteriovenous malformation, a disease characterized by high flow. With this method, we were able to accurately detect the elevated blood velocities and exaggerated pulsatility along the abnormal vascular network in these animals. LS-PIV robustly analyzed noisy data from vessels as deep as 850 µm below the brain surface. In addition to analyzing in vivo data, we validated the accuracy of LS-PIV up to 800 mm/s using simulations with known velocity and noise parameters.
CONCLUSIONS/SIGNIFICANCE: To our knowledge, these blood velocity measurements are the fastest recorded with TPLSM. Partnered with transgenic mice carrying cell-specific fluorescent reporters, LS-PIV will also enable the direct in vivo correlation of cellular, biochemical, and hemodynamic parameters in high flow vascular development and diseases such as atherogenesis, arteriogenesis, and vascular anomalies.
测量血流速度对于研究血管发育、生理学和病理学至关重要。一个关键挑战是在具有细胞分辨率的活体标本中，对处于深层位置的血管内的广泛血流速度进行量化，同时对血管细胞进行衍射极限分辨率的成像。双光子激光扫描显微镜（TPLSM）在分析动物体内深达数百微米的血流速度方面显示出巨大的潜力，具有细胞分辨率。然而，目前基于 TPLSM 的数据分析仅限于血流速度的较低范围，不足以研究许多正常或疾病条件下的更快速度。
方法/主要发现：我们开发了线扫描粒子图像测速（LS-PIV），它使用 TPLSM 数据来量化活体携带脑动静脉畸形（一种以高流量为特征的疾病）的小鼠中高达 84mm/s 的峰值血流速度。通过这种方法，我们能够准确地检测到这些动物异常血管网络中升高的血流速度和夸张的脉动性。LS-PIV 可以稳健地分析来自大脑表面以下深达 850μm 的血管的噪声数据。除了分析体内数据外，我们还使用具有已知速度和噪声参数的模拟来验证 LS-PIV 高达 800mm/s 的准确性。
结论/意义：据我们所知，这些血流速度测量是 TPLSM 记录的最快速度。与携带细胞特异性荧光报告基因的转基因小鼠结合使用，LS-PIV 还将能够直接在高流量血管发育和动脉粥样硬化、血管生成和血管异常等疾病中对细胞、生化和血液动力学参数进行体内相关性研究。
