Frequency wavelength multiplexed optoacoustic tomography

Abstract

Optoacoustics (OA) is overwhelmingly implemented in the Time Domain (TD) to achieve high signal-to-noise ratios by maximizing the excitation light energy transient. Implementations in the Frequency Domain (FD) have been proposed, but suffer from low signal-to-noise ratios and have not offered competitive advantages over time domain methods to reach high dissemination. It is therefore commonly believed that TD is the optimal way to perform optoacoustics. Here we introduce an optoacoustic concept based on pulse train illumination and frequency domain multiplexing and theoretically demonstrate the superior merits of the approach compared to the time domain. Then, using recent advances in laser diode illumination, we launch Frequency Wavelength Multiplexing Optoacoustic Tomography (FWMOT), at multiple wavelengths, and experimentally showcase how FWMOT optimizes the signal-to-noise ratios of spectral measurements over time-domain methods in phantoms and in vivo. We further find that FWMOT offers the fastest multi-spectral operation ever demonstrated in optoacoustics.

Injectable‐Hydrogel‐Based Tissue Sealant for Hemostasis, Bacteria Inhibition, and Pro‐Angiogenesis in Organ Bleeding Wounds and Therapeutic Outcome Monitoring Via NIR‐II Optical Imaging

“…NIR‐II fluorescent imaging (900–1700 nm emission) is advantageous for bioimaging in terms of operational ease and imaging clarity due to the long wavelength used; while, MSOT imaging featuring higher spatial resolution and 3D MSOT imaging is conducive to offering 3D information about the wound site. [ 55–75 ] To track the wound healing progress in a noninvasive manner, the AN@CD‐PEG&TQ‐treated mice underwent NIR‐II fluorescent/MSOT imaging on days 1, 3, and 5 (Figure 3F–G; Figure S26–S32, Supporting Information). Clearly the signals were always at the wound site, again confirming the strong tissue adhesion of AN@CD‐PEG&TQ.…”

Tumor Microenvironment Activated Photoacoustic-Fluorescence Bimodal Nanoprobe for Precise Chemo-immunotherapy and Immune Response Tracing of Glioblastoma

“…The PAI provided volumetric images of vascular morphology and Treg cells distribution in superficial tumor tissues simultaneously, using 532 and 770 nm. The absorption of endogenous hemoglobin at 532 nm allowed visualization of tumor neoangiogenesis, while the absorption of exogenous PEG/αCD25-Cy7/TMZ nanoprobe at 770 nm served as a contrast for mapping the distributions of Treg cells. − After injection of PEG/αCD25-Cy7/TMZ nanoprobe, the tumor site was irradiated by pulsed laser with 770 nm, and the dynamic information on Treg cells was monitored by the PAM during chemotherapy process (Figure A, S8). To avoid thermal damage of the tumor, the energy density of the pulsed laser at 770 nm was set at 20 mJ/cm 2 .…”

Optoacoustic Endoscopy of the Gastrointestinal Tract

“…Q-switch pumped OPO (optical parametric oscillator) systems have been used to implement a multispectral OA imaging system. , However, in addition to being bulky in size and high-cost, the low pulse repetition rate and wavelength-tuning speed of OPO systems significantly limit the imaging speed, making them impractical for in vivo 3D endoscopy imaging. For this reason, laser diodes (LD) and light emitting diodes (LED) have demonstrated potential as promising alternatives to solid-state laser sources for OA imaging. − These new laser sources can provide high repetition rates and a wide range of wavelengths and are also low-cost. These advantages could allow for real-time OA endoscopic imaging of the human GI lumen wall with similar scanning speeds to OCT endoscopy, an imaging modality that has already been validated for the clinical environment.…”