Biological Flow Measurement Using Optical Flow Method

The physics based optical flow method (OFM) was explored and applied to the blood flow measurement based on the digital subtraction angiography X-ray images. The objective of the present study is to examine the applicability of the physics-based OFM in the biological flow and evaluate the accuracy of OFM in recovering the velocity of blood flow in cerebral arteries. In order to examine the algorithm and conduct the error analysis, simulations are conducted on synthetic grid images (640×480 piexiels and 8 bits), where the intensity profiles across a grid line is Gaussian. The recovered velocity from OFM agrees well with the exact velocity distribution. Then, the improved OFM algorithm was applied on the DSA images of cerebral arteries including the cerebral arterial aneurysm and the parent internal cerebral artery. Again, synthetic parabolic velocity distribution and Oseen vortices were imposed to the vessel image and aneurysm image respectively to examine the accuracy of the current method. Compared to the grid image, the DSA image featured as low-intensity and isotropic distribution challenges the OFM algorithm. Appropriate intensification process combined with Gaussian filtering are applied to improve the accuracy of the OFM estimation. Finally the improved OFM was applied to the in-vivo measurement of the blood flow in the aneurysm to analyze the blood velocity distribution and hemodynamics.