Ultrasound modulated laser confocal feedback imaging inside turbid media

Abstract

Ultrasound modulated laser confocal feedback technology is proposed in the imaging inside turbid media. By selecting the detectable signal photons and rejecting the background noise photons in the frequency domain based on the ultrasound modulation, the signal-to-noise ratio (SNR) can be much improved, especially in the turbid media, compared with the traditional imaging without ultrasound modulation. This is a promising method to reach both a larger penetration depth and a better SNR than other optical methods.

Frequency-Shifted Optical Feedback Measurement Technologies Using a Solid-State Microchip Laser

“…However, the system is also challenged to realize both high resolution and large penetration depth the same as the other optical methods. Therefore, combining other technologies with the advantages of the laser confocal feedback tomography is interesting research, such as the numerically reconstructing imaging to extend the DOF and ultrasound-modulated technology to improve the SNR [96,97].…”

“…The quality of the laser confocal feedback imaging is also affected by the scattered photons [39], and the generated speckles reduce the image contrast as well as the SNR. To solve the problem, Zhu [97] applied the ultrasound-modulated technology in the laser confocal feedback imaging. The system is shown in Figure 26.…”

Ultrasound-Enhanced Chemiluminescence for Bioimaging

“…Using FUS at different stimulation levels, authors not only observed 10 times higher signal-to-noise ratio (Zhu et al, 2018) for 1064 nm luminescent laser but also increased sensitivity or better spatial resolution. The best resolution was reported at 2 mm (Ahmad et al, 2017;Klein et al, 2018) using 640 nm laser or 18 F lasers.…”

“…In order to mimic tissue environments, agarose phantom is usually used as it has similar scattering coefficient as that of native tissues following Monte Carlo model (Wang et al, 1995). Since native tissues may vary from species to species, phantoms typically have a scattering coefficient from 1 to 80 cm −1 (Kobayashi et al, 2016;Ahmad et al, 2017;Zhu et al, 2018). Through phantoms, transparent silicon tubes were run at different depths.…”

“…In most cases in literature, we can see that the more powerful the FUS, the greater the penetration and resolution. For instance, once FUS was increased from 1 to 2 MHz, signals were 10 times stronger as normalized to background (Klein et al, 2018;Zhu et al, 2018) while increasing FUS from 2 to 3 MHz allowed fourfold deeper penetration and 33% better resolution (Ahmad et al, 2017;Zhu et al, 2018).…”