Advances in Endoscopic Photoacoustic Imaging

Abstract

Photoacoustic (PA) imaging is able to provide extremely high molecular contrast while maintaining the superior imaging depth of ultrasound (US) imaging. Conventional microscopic PA imaging has limited access to deeper tissue due to strong light scattering and attenuation. Endoscopic PA technology enables direct delivery of excitation light into the interior of a hollow organ or cavity of the body for functional and molecular PA imaging of target tissue. Various endoscopic PA probes have been developed for different applications, including the intravascular imaging of lipids in atherosclerotic plaque and endoscopic imaging of colon cancer. In this paper, the authors review representative probe configurations and corresponding preclinical applications. In addition, the potential challenges and future directions of endoscopic PA imaging are discussed.

Circular array transducer based-photoacoustic/ultrasonic endoscopic imaging with tunable ring-beam excitation

“…Wang’s group intervened a single ultrasonic transducer-based PAE/EUS into esophagus of rabbits, acquiring the photoacoustic and ultrasonic images of surrounding tissues and proximal organs in vivo [19] . Then several PAE/EUS systems with full field-of-view have been proposed by Chen’s group, Song’s group, Xing’s group and Zhu’s group, to visualize the vasculature on colorectum wall in vivo [20] , [21] , [22] , [23] , [24] . Recently, Ntziachristos’s group proposed a capsule endoscopy with outer diameter of 16 mm and imaging speed of video rate of 50 Hz [25] .…”

A practical guide for model-based reconstruction in optoacoustic imaging

“…Various types of sensors with detection bandwidth tailored to the desired resolution-depth range [13][14][15][16] and acquisition geometries (i.e. spatial distribution of US detectors relative to the sample) have further been developed [17][18][19][20][21][22]. Many of these systems have found use in biomedical research studies and clinical applications [23][24][25][26][27][28].…”

A Transparent Ultrasound Array for Real-Time Optical, Ultrasound, and Photoacoustic Imaging

“…For imaging atherosclerosis, a cardiovascular disease characterized by the accumulation of lipid plaques and several fibrous and cellular constituents, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) technologies are commonly used in the clinics [16][17][18]. Recently, intravascular PA (IVPA) is also being actively studied for mapping deep tissue atherosclerosis based on high optical absorption contrast of plaque lipids in the NIR-IIb (1.5 μm-1.7 μm) optical window [19][20][21][22][23]. Similarly, neuroscience studies also require high-resolution multiparametric hemodynamic information (cerebral blood flow, blood volume, and oxygen saturation) obtained from optical and photoacoustic imaging for mapping resting state brain connectivity [24][25][26], studying neuromodulation [27], neurovascular coupling [28][29][30], and neurodiseases [31][32][33].…”