Laser OptoAcoustic Tomography: Towards New Technology for Biomedical Diagnostics

Abstract

This paper provides a short review of physical principles, technology, biomedical applications and perspectives of the optoacoustic imaging. Ideas that made this rapidly developing field possible include the following: (1) laser pulses may be effectively used to produce acoustic pressure in biological tissues localized to the areas of increased optical absorption, (2) the resulting acoustic (ultrasonic) waves propagate in tissues with minimal distortions and attenuation, (3) 2D and 3D maps (images) of the absorbed optical energy can be reconstructed with high resolution from the detected optoacoustic signals. Modern optoacoustic imaging systems include scanning focused transducers and 2D/3D transducer arrays. The widely accepted 2D arrays are employed either for real-time 2D optoacoustic imaging or for 3D imaging via translational or rotational scanning. A commercial prototype of a 3D OAT system is being developed by TomoWave Labs where major biomedical applications include visualization of specific targeting using exogenous optoacoustic contrast agents and imaging of blood distribution and oxygentaion status can be investigated.

Keywords: gold nanorods; in-vivo imaging; optoacoustic tomography; preclinical research.

Figure 1

Diagrams of the two commercial systems in development for optoacoustic tomography: (a) tank and (b) bowl systems

Figure 2

Diagram showing distribution of the acoustic transducers after a complete rotational scan of the 3D OAT system.

Figure 3

Volumetric representations of mice scans taken at different wavelengths with different processing and visualization in order to see different structures in a live mouse

Figure 4

Biodistribution of gold nanorods studied in live mouse using 3D optoacoustic imaging. (a) – image prior to GNR injection; (b) – image at 1hr following the injection; (c) – image at 2 days following the injection.