Visualization and Quantification of the Cell-free Layer in Arterioles of the Rat Cremaster Muscle.
The cell-free layer is defined as the parietal plasma layer in the microvessel flow, which is devoid of red blood cells. The measurement of the in vivo cell-free layer width and its spatiotemporal variations can provide a comprehensive understanding of hemodynamics in microcirculation. In this study, we used an intravital microscopic system coupled with a high-speed video camera to quantify the cell-free layer widths in arterioles in vivo. The cremaster muscle of Sprague-Dawley rats was surgically exteriorized to visualize the blood flow. A custom-built imaging script was also developed to automate the image processing and analysis of the cell-free layer width. This approach enables the quantification of spatiotemporal variations more consistently than previous manual measurements. The accuracy of the measurement, however, partly depends on the use of a blue filter and the selection of an appropriate thresholding algorithm. Specifically, we evaluated the contrast and quality of images acquired with and without the use of a blue filter. In addition, we compared five different image histogram-based thresholding algorithms (Otsu, minimum, intermode, iterative selection, and fuzzy entropic thresholding) and illustrated the differences in their determination of the cell-free layer width.
NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore; Department of Biomedical Engineering, National University of Singapore.
Yan Cheng
YC
Ng
Department of Biomedical Engineering, National University of Singapore.
Liam K
LK
Fisher
Department of Biomedical Engineering, National University of Singapore.
Veena
V
Salim
NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore; Department of Biomedical Engineering, National University of Singapore; Department of Surgery, National University of Singapore.
Sangho
S
Kim
Department of Biomedical Engineering, National University of Singapore; cienab@nus.edu.sg.
Bumseok
B
Namgung
D000009:Abdominal Muscles; D000818:Animals; D001160:Arterioles; D007091:Image Processing, Computer-Assisted; D008833:Microcirculation; D008853:Microscopy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014741:Video Recording