Image reconstruction in optoacoustics usually employs algorithms that assume ultrasonic transducers to be confined to points. This assumption deviates strongly from realistic detectors and is the cause of severe artifacts in the reconstructions. We propose two model-based image reconstruction algorithms that account for the shape of cylindrically focused ultrasonic transducers in three-dimensional optoacoustic tomography. The algorithms have been proved favorable in simulations and experiments.
Cross sectional tomographic systems based on cylindrically focused transducers are widely used in optoacoustic (photoacoustic) imaging due to important advantages they provide such as high-cross sectional resolution, real-time imaging capacity, and high-throughput performance. Tomographic images in such systems are commonly obtained by means of two-dimensional (2-D) reconstruction procedures assuming point-like detectors, and volumetric (whole-body) imaging is performed by superimposing the cross sectional images for different positions along the scanning direction. Such reconstruction strategy generally leads to in-plane and out-of-plane artifacts as well as significant quantification errors. Herein, we introduce two equivalent full three-dimensional (3-D) models capable of accounting for the shape of cylindrically focused transducers. The performance of these models in 3-D reconstructions considering several scanning positions is analyzed in this work. Improvements of the results rendered with the introduced reconstruction procedure as compared with the 2-D-based approach are described and discussed for simulations and experiments with phantoms and biological tissues.
The discrepancy between optoacoustic reconstruction algorithms assuming point-like and realistic finite-size transducers causes severe artifacts. Two model-based algorithms accounting for finite-size of cylindrically focused detectors are presented and its performance tested in simulations and experiments.
Frequency domain optoacoustics relates to stimulation of optoacoustic signals using intensity modulated continuous wave light instead of pulsed laser light employed in time domain optoacoustic imaging. We present a method to generate frequency domain tomographic images of optical absorbers and cross sectional <i>in-vivo</i> mouse images, showing the changes of optical absorption before and after injection of indocyanine green (ICG). OCIS codes: 170.6960, 170.3880, 170.5220