Reversibly switchable photoacoustic imaging systems and methods

Abstract

Reversibly switchable photoacoustic tomography (RS-PAT), a photoacoustic technique with enhanced sensitivity and resolution, is disclosed. RS-PAT utilizes a subtractive process for the formation of a photoacoustic image of a region containing a plurality of switchable photoacoustic probes. In various aspects, the photoacoustic detection in RS-PAT imaging occurs minimally twice: a first image obtained when the photoacoustic probe is in active (absorbing or ON) state and a second image obtained when the photoacoustic probe is in an inactive (less-absorbing or OFF) state. Subtraction of the second image from the first image is used to obtain the RS-PAT image.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT[0001]This invention was made with government support under grants R01 CA186567 and DP1 EB016986 awarded by the National Institutes of Health. The government has certain rights to the invention.BACKGROUND[0002]Using reporter genes that can be selectively expressed in targeted biological processes, optical imaging has provided valuable information for biomedical studies at different length scales. However, strong light scattering in tissue leads to a substantial tradeoff between the spatial resolution and penetration depth, even in advanced optical imaging techniques. Photoacoustic (PA) tomography (PAT), on the other hand, breaks the depth and resolution limitations of pure optical imaging by acoustically detecting optical absorption contrast. In PAT, light-induced ultrasound waves are detected outside tissue to form an image that maps the original optical energy deposition inside the tissue. The weak ultrasonic scattering...

AI Technical Summary

Benefits of technology

The patent describes a method and system for obtaining an image of a region of interest using reversibly-switchable probes that can be switched between a first state and a second state. The first state is a first laser pulse wavelength, and the second state is a second laser pulse wavelength. The method includes obtaining a first PA signal from the region of interest using the first laser pulse wavelength, switching the probes from the first state to the second state, obtaining a second PA signal from the region of interest using the first laser pulse wavelength, and reconstructing a first PA image of the region of interest from the first PA signals and a second PA image of the region of interest from the second PA signals to obtain the RS-PA image of the region of interest. The system includes a laser source for producing the first and second laser pulses, a controller for controlling the timing of the laser pulses, an optical combining module for directing the laser pulses into the region of interest, and an ultrasound transducer for receiving the PA signals. The technical effect is a method and system for obtaining higher-resolution images of a region of interest using RS-PA imaging.

Problems solved by technology

However, strong light scattering in tissue leads to a substantial tradeoff between the spatial resolution and penetration depth, even in advanced optical imaging techniques.

However, existing GFP-like FPs lack strong optical absorption at wavelengths beyond 610 nm and are prone to photobleaching and therefore are less well-suited for deep-tissue PAT.

Accurate spectral unmixing of these biomolecules is hampered by highly wavelength-dependent light attenuation in tissue at depths beyond the optical diffusion limit.

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