Abstract
.Significance: Nanosecond-pulsed laser has proven to be used to obtain the velocity of blood using the speckle contrast method. Without the scanning time, it has potential for achieving fast two-dimensional blood flow images in a photoacoustic imaging system with the same pulsed laser.Aim: Our study aimed to evaluate the qualities of regional cerebral blood flow (rCBF) obtained in a laser speckle contrast imaging (LSCI) system using continuous wave (cw) and nanosecond pulse laser sources.Approach: First, a LSCI system consisting of a cw laser with a wavelength of 632.8 nm and a cw laser/nanosecond pulse laser with a wavelength of 532 nm was developed. This system was used to obtain rCBF images of mouse in vivo with two different laser sources.Results: Continuous wave lasers (532 and 632.8 nm) show different imaging characteristics for rCBF imaging. The rCBF images obtained using 532-nm nanosecond pulse laser showed higher resolution than those using 532-nm cw laser. There was no significant difference in the results using nanosecond pulse laser among various pulse widths or repetition rates.Conclusions: It is proved that a nanosecond pulse laser could be used for LSCI.
Highlights
Many diseases, such as cardiovascular diseases, atherosclerosis, diabetes, and chronic venous insufficiency, cause functional and morphological changes in blood flow.[1,2] The dynamic monitoring of blood flow has great value in life science research, drug evaluation, clinical diagnosis, clinical application, and surgical guidance
By comparing the images under white light, it was found that the 532-nm nanosecond pulse laser showed a good blood flow image on the blood vessels of the mouse brain at deeper depth
The results showed that the change of pulse width had little effect on the experimental results of regional cerebral blood flow (rCBF) imaging in mice, and all the results showed similar information of blood vessel and blood flow
Summary
Many diseases, such as cardiovascular diseases, atherosclerosis, diabetes, and chronic venous insufficiency, cause functional and morphological changes in blood flow.[1,2] The dynamic monitoring of blood flow has great value in life science research, drug evaluation, clinical diagnosis, clinical application, and surgical guidance. Some effective measurement methods for living animal tissues, especially blood vessels, are being studied, such as magnetic resonance perfusion imaging, positron emission tomography (PET), x-ray angiography, fluorescence angiography, and laser Doppler flowmeter. There are some limitations in these blood flow imaging techniques.[3,4,5] For example, magnetic resonance imaging (MRI) perfusion imaging and PET are mostly used for holistic imaging with low spatial and temporal resolution and high cost. Doppler flowmeter can only provide a single point of monitoring that does not provide a complete two-dimensional (2-D) map of blood flow velocity.[6,7,8,9] Compared to other imaging techniques, laser speckle contrast imaging (LSCI) provides 2-D full-speed blood flow distribution with lower cost
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