Abstract: Objective To estatblish a real-time fluorescence imaging method for observing arterial blood spiral laminar flow. Methods Sprague Dawley rats were randomly divided into vein angiography group (femoral vein injection, 1 mL/kg) and low-dose arteriography group (abdominal aortic injection, 0.1 mL/kg). The low-dose arteriography group was further divided into fluorescein sodium group, rhodamine B group, FITC-dextran group and quantum dot group (n=7 for each group). The dynamic images were captured with high-speed camera. The fluorescence region was calibrated by image threshold segmentation algorithm and morphological post-processing algorithm. The axial velocity and tangential velocity of helical blood flow in rat femoral artery were measured, and the screw pitch and shear force were calculated. Results Compared with the vein angiography group, the low-dose arteriography group clearly showed the clockwise spiral laminar flow in the femoral artery of rats. In the FITC-dextran group, the axial velocity of blood spiral laminar flow was (198.4±112.7)mm/s, and the tangential velocity was(3.3±0.8)mm/s.The screw pitch was (126.1±76.3)mm, and the shear force was (9.5±5.6)Pa. The injections were repeated three times for each rat, and there was no significant difference among each injection. Conclusions Real-time fluorescence imaging can be used to observe arterial blood spiral laminar flow in vivo and to quantitatively analyze the hemodynamic characteristics of spiral laminar flow.

Key words: artery, spiral laminar flow, fluorescence imaging, wall shear stress