Three-dimensional blood vessel and velocity imaging visualizes occlusions

Blood vessels circulate oxygen and essential nutrients from our heart and lungs to all of our organ systems. When this flow is disrupted, as in peripheral artery disease (PAD), blood vessels and nerves are damaged. Visualization of blood flow velocity along with blood vessel positioning allows for targeted, quantitative measurements of blood flow abnormalities and could provide earlier detection of life threatening blood occlusions.

Researchers in Japan report in the Journal of Applied Physics on the use of two-beam multipoint laser Doppler velocimetry (MLDV) and blood cell light scattering for in vivo visualization of blood flow with 3-D imaging. Two-beam MLDV uses an intersection region, the overlap of an achromatic lens and rod lenses, where Doppler interference photons from points in the measurement region are collected and directed to an optical fiber array. The array’s 40 linearly arranged fibers simultaneously measure the velocity distribution in the intersection region.

Measurements were taken on a mouse’s ear, where blood vessel occlusion was induced using the photochemical blockage of green laser irradiation with rose bengal. Shifting of the measurement line using a motorized stage, in x, y and z directions, and stacking of the resulting 2-D images produced the final 3-D images.

Combing optical absorption measurements by red blood cells, and subsequent light scattering with the MLDV data, then offered the ability to estimate a blood vessel’s position within the larger circulatory system. The ability to locate such an occlusion could mean broader detection applications for this MLDV technique in patients with diabetes or PAD, as well as other clinical applications in need of in vivo blood flow detection.

Source: “Three-dimensional imaging of absolute blood flow velocity and blood vessel position under low blood flow velocity based on Doppler signal information included in scattered light from red blood cells,” by Tomoaki Kyoden, Shunsuke Akiguchi, Tomoki Tajiri, Tsugunobu Andoh, and Tadashi Hachiga, Journal of Applied Physics (2017). The article can be accessed at https://doi.org/10.1063/1.4994080 .