Combating acoustic heterogeneity in photoacoustic computed tomography: A review

Abstract

Based on the energy conversion of light into sound, photoacoustic computed tomography (PACT) is an emerging biomedical imaging modality and has unique applications in a range of biomedical fields. In PACT, image formation relies on a process called acoustic inversion from received photoacoustic signals. While most PACT systems perform this inversion with a basic assumption that biological tissues are acoustically homogeneous, the community gradually realizes that the intrinsic acoustic heterogeneity of tissues could pose distortions and artifacts to finally formed images. This paper surveys the most recent research progress on acoustic heterogeneity correction in PACT. Four major strategies are reviewed in detail, including half-time or partial-time reconstruction, autofocus reconstruction by optimizing sound speed maps, joint reconstruction of optical absorption and sound speed maps, and ultrasound computed tomography (USCT) enhanced reconstruction. The correction of acoustic heterogeneity helps improve the imaging performance of PACT.

Image Quality Improvement Techniques and Assessment Adequacy in Clinical Optoacoustic Imaging: A Systematic Review

“…The boundaries between tissues of highly contrasting acoustic properties (e.g., bone surfaces) reflect incident waveforms back towards the imaging probe, generating reflection artifacts [ 36 ] ( Figure 4 d), which may overlap with other image features of interest, or be mistaken as regions of actual optical absorption. Unknown variations in acoustic speed also challlenge reconstruction algorithms that naively assume constant SoS inside tissue, distorting the reconstructed images [ 39 ].…”

“…Many factors reduce or limit the quality of optoacoustic images, which, in turn, hinder the modality’s potential for clinical translation. These factors may emerge from the imaging hardware [ 25 , 26 , 27 , 28 , 29 , 30 ], the inexact or approximative image reconstruction algorithms [ 25 , 26 , 31 , 32 , 33 ], the attenuative properties and inhomogeneous nature of tissue (light-tissue interaction phenomena) [ 34 , 35 , 36 , 37 , 38 , 39 ], or particularities of the acquisition procedure [ 40 , 41 ], and manifest as image noise, artifacts, and poor overall image fidelity.…”

A practical guide for model-based reconstruction in optoacoustic imaging

“…The great diversity of possible hardware designs represents an important advantage of the OA technology [29]. On the other hand, significant variability of image formation approaches, independently developed for each particular configuration [30][31][32][33], may compromise reproducibility and reliability of the reported experimental results thus hindering the development of standardized methodologies enabling accurate quantification of bio-markers [34].…”

Multi-segmented feature coupling for jointly reconstructing initial pressure and speed of sound in photoacoustic computed tomography

“…7,8 However, considering that the SoS inside soft tissues varies from 1350 (fat) to 1700 m∕s (skin), 9,10 such an assumption can sometimes be too rough and can consequently cause splitting, blurring, and distortions of structural features, thus impeding many kinds of quantification tasks. 11,12 Studies have shown that, by integrating ultrasound tomography, the acoustic properties in the imaged field of view, including the SoS and acoustic attenuation, can be reconstructed at the expense of system complexity. [13][14][15] Another type of approach employs a model-based procedure to jointly reconstruct (JR) the acoustic properties and the photoacoustic IP by iteratively updating the numerical model to match the experimental data.…”