title: Line-scanning particle image velocimetry: an optical approach for quantifying a wide range of blood flow speeds in live animals.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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
  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.
authors: Laboratory for Accelerated Vascular Research, Division of Vascular Surgery, Department of Surgery, University of California San Francisco, San Francisco, California, United States of America.
authors: Tyson N
authors: TN
authors: Kim
authors: Patrick W
authors: PW
authors: Goodwill
authors: Yeni
authors: Y
authors: Chen
authors: Steven M
authors: SM
authors: Conolly
authors: Chris B
authors: CB
authors: Schaffer
authors: Dorian
authors: D
authors: Liepmann
authors: Rong A
authors: RA
authors: Wang
mesh_terms: D000818:Animals; D001165:Arteriovenous Malformations / Q000473:pathology*; D001783:Blood Flow Velocity / Q000502:physiology*; D001921:Brain / Q000166:cytology; D001927:Brain Diseases / Q000473:pathology*; D058948:Cell Tracking; D036388:Ephrin-B2 / Q000502:physiology; D004912:Erythrocytes / Q000473:pathology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006439:Hemodynamics; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D011518:Proto-Oncogene Proteins / Q000502:physiology; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000502:physiology; D012212:Rheology
chemical_list: D036388:Ephrin-B2; D011518:Proto-Oncogene Proteins; D000074562:Receptor, Notch4; D051880:Receptors, Notch; C073572:Notch4 protein, mouse; D049452:Green Fluorescent Proteins