Full-Wave Iterative Image Reconstruction in Photoacoustic Tomography With Acoustically Inhomogeneous Media

Abstract

Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated by use of both computer-simulated and experimental PACT measurement data.

Stochastic Proximal Gradient Algorithms for Multi-Source Quantitative Photoacoustic Tomography

“…One important reconstruction problem in PAT is recovering the initial pressure distribution (see, for example, [3][4][5][6][7][8][9][10]). The initial pressure distribution only provides qualitative information about the tissue-relevant parameters, as it is the product of the optical absorption coefficient and the spatially varying optical intensity, which again indirectly depends on the tissue parameters.…”

Multiview Hilbert transformation in full-ring transducer array-based photoacoustic computed tomography

“…However, in addition to relying on a high signal-to-noise ratio (SNR), deconvolution does not solve the limited elevational acoustic coverage issue and, thus, cannot provide unipolar reconstructed images for FR-PACT. A third solution is to employ iteration-based image reconstruction with a nonnegativity constraint, [21][22][23] although this requires accurate modeling of the imaging system and time-consuming computation. In addition to these three methods, Hilbert transformation is widely used in PAM and linear array-based PACT to address bipolarity and extract envelope information, and it has been proven to be simple and computationally effective.…”

High frame rate photoacoustic imaging at 7000 frames per second using clinical ultrasound system

“…Ultrasound detectors (single or multiple or array detectors) acquire these PA waves outside the sample boundary. Reconstruction techniques are used to form the optical absorption map of the inside of the object [16][17][18][19][20]. PAT has several advantages including deeper penetration depth, good spatial resolution, and high soft tissue contrast in comparison to other optical imaging modality like optical microscopy or optical coherence tomography.…”

“…For the light excitation source, usually, a Nd:YAG pump laser either pumps a dye laser or an Optical parametric oscillator (OPO) laser to generate light in the NIR wavelengths. But, these types of lasers are bulky (often requiring an optical table to house the laser), expensive, and slow (typical pulse repetition rate for such lasers is [10][11][12][13][14][15][16][17][18][19][20] Hz with ~100 mJ of energy per pulse), making the PAT system difficult to translate into clinical setup. Therefore, there is a need to develop PAT system which is compact, affordable, portable and have a higher frame rates [26,27].…”