Application of photoacoustic computed tomography in biomedical imaging: A literature review

Abstract

Photoacoustic computed tomography (PACT) is a hybrid imaging modality that combines optical excitation and acoustic detection techniques. It obtains high‐resolution deep‐tissue images based on the deep penetration of light, the anisotropy of light absorption in objects, and the photoacoustic effect. Hence, PACT shows great potential in biomedical sample imaging. Recently, due to its advantages of high sensitivity to optical absorption and wide scalability of spatial resolution with the desired imaging depth, PACT has received increasing attention in preclinical and clinical practice. To date, there has been a proliferation of PACT systems designed for specific biomedical imaging applications, from small animals to human organs, from ex vivo to in vivo real‐time imaging, and from simple structural imaging to functional and molecular imaging with external contrast agents. Therefore, it is of great importance to summarize the previous applications of PACT systems in biomedical imaging and clinical practice. In this review, we searched for studies related to PACT imaging of biomedical tissues and samples over the past two decades; divided the studies into two categories, PACT imaging of preclinical animals and PACT imaging of human organs and body parts; and discussed the significance of the studies. Finally, we pointed out the future directions of PACT in biomedical applications. With the development of exogenous contrast agents and advances of imaging technique, in the future, PACT will enable biomedical imaging from organs to whole bodies, from superficial vasculature to internal organs, from anatomy to functions, and will play an increasingly important role in biomedical research and clinical practice.

Visualization of Microcirculation at Acupoints in vivo of Alzheimer’s Disease Animal Model with Photoacoustic Microscope: A Pilot Study

“…The spatial arrangement of this biological data inside the organism was indicative of the tissue’s functionality and pathological condition. A more in-depth examination of this data might provide significant foundational knowledge for the timely identification, intermediate therapeutic evaluation, and ultimate treatment results of many diseases within the field of biomedical sciences [ 66, 67 ].…”

Review of imaging test phantoms

“…28 In addition, advancements in imaging systems, such as the use of sophisticated array designs, high-speed lasers, and deep-learning-based algorithms, contribute to the performance of PAT by enabling faster data acquisition and improved image reconstruction. 29 2 Simple Phantoms A simple phantom, characterized by minimal manufacturing complexity, typically comprises one or two major components. These phantoms find extensive application across various domains and can be further classified into three sub-categories: simple tube/channel phantoms, naturally occurring phantoms (simple), and simple block phantoms.…”

“… 28 In addition, advancements in imaging systems, such as the use of sophisticated array designs, high-speed lasers, and deep-learning-based algorithms, contribute to the performance of PAT by enabling faster data acquisition and improved image reconstruction. 29 …”

Review of Deep Learning Approaches for Interleaved Photoacoustic and Ultrasound (PAUS) Imaging

“…Many PA systems have been developed that optimize the laser source, irradiation geometry, and sound detectors for a specific application [ 11 ], [ 12 ], [ 13 ], [ 14 ], [ 15 ], [ 16 ], [ 17 ], [ 18 ], [ 19 ], [ 20 ], [ 21 ], [ 22 ]. Among them, PA-computed tomography (PACT) reconstructs a macroscopic image with relatively deep penetration (a few centimeters) by strategically combining PA signals emitted from the entire ROI and detected by multiple sensors [ 23 ], [ 24 ].…”

“…The universal back-projection (UBP) algorithm derived from the spherical Radon transform reconstructs a quantitative map of optical absorption from PA measurements provided that the detection array is full view and full bandwidth [ 25 ], the laser fluence distribution in the medium is known, and the medium is acoustically and thermally homogeneous. PACT generally uses a hemisphere or cylindrical sensor array to surround a target, so the main applications have been small animal imaging or monitoring human breast disease [ 19 ].…”