Two hundred years ago, a doctor from France used a stethoscope for the first time and countless efforts to observe human body have been made since then. Up to now, the best tool that provides anatomical, functional, and molecular information of human and animal is the photoacoustic microscopy. Super-resolution localization photoacoustic microscopy, which is 500 times faster than the conventional photoacoustic microscopy system, has been developed by a research team from POSTECH in Korea.
Chulhong Kim, Jinyoung Kim and Jongbeom Kim present a fast photoacoustic microscopy system with custom-made scanning mirror in a paper published by n Nature's Light: Science and Applications. This newly developed microscopy uses a stable and commercial galvanometer scanner with a custom-made scanning mirror and can find blocked or burst blood vessels by monitoring the flow of red blood cells without using a contrast absorber.
The photoacoustic microscopy images cells, blood vessels and tissues by inducing vibrations when the optic energy is converted to heat after an object absorbs light from the laser beam fired. Conventional photoacoustic microscopy systems, which use a galvanometer scanner, have a narrow field of view because they do not scan photoacoustic waves, only the optical beam. Conventional photoacoustic microscopy systems using a linear motorized stage also have temporal limitation in making images.
The research team developed a new photoacoustic microscopy system with improved performances. It can scan both photoacoustic waves and optical beams simultaneously, as the reseachers implemented a custom-made scanning mirror into the existing photoacoustic microscopy system. The system can monitor very small vessels using intrinsic red blood cells without a contrast absorber. Furthermore, the new system is 500 times faster than that of conventional ones. With this improvement, it can demonstrate super-resolution images by localizing photoacoustic signals. Lastly, spatial resolution is enhanced by 2.5 times.
This system is expected to show promise in the diagnosis and treatment of stroke and cardiovascular disease. Because it can monitor and image blood vessels with the flow of blood cells in real-time, it can also be used in vascular disease, which needs urgent diagnosis and treatment. Moreover, it allows direct monitoring of hemodynamics in the microvessels. It is suited for use in various fields, including hemodynamic response, contrast agent dynamics in blood vessels and transient microcirculatory abnormalities.
"We successfully imaged microvessels in the ears, eyes and brains of mice, as well as a human fingertip with this new photoacoustic microscopy system. What we have developed can be a complementary tool to the conventional brain imaging system, and it can also be a promising tool for future preclinical and clinical studies," said Kim.