Organosilicon phantom for photoacoustic imaging

Abstract

Photoacoustic imaging is an emerging technique. Although commercially available photoacoustic imaging systems currently exist, the technology is still in its infancy. Therefore, the design of stable phantoms is essential to achieve semiquantitative evaluation of the performance of a photoacoustic system and can help optimize the properties of contrast agents. We designed and developed a polydimethylsiloxane (PDMS) phantom with exceptionally fine geometry; the phantom was tested using photoacoustic experiments loaded with the standard indocyanine green dye and compared to an agar phantom pattern through polyethylene glycol-gold nanorods. The linearity of the photoacoustic signal with the nanoparticle number was assessed. The signal-tonoiseratio and contrast were employed as image quality parameters, and enhancements of up to 50 and up to 300%, respectively, were measured with the PDMS phantom with respect to the agar one. A tissue-mimicking (TM)-PDMS was prepared by adding TiO2 and India ink; photoacoustic tests were performed in order to compare the signal generated by the TM-PDMS and the biological tissue. The PDMS phantom can become a particularly promising tool in the field of photoacoustics for the evaluation of the performance of a PA system and as a model of the structure of vascularized soft tissues.

Sulfates as chromophores for multiwavelength photoacoustic imaging phantoms

“…Low propensity for permanent photobleaching. 9,13,17 This is essential when the imaging system requires the use of multiple illumination shots or when the same phantom will be used multiple times, both to prevent the absorption spectrum from changing over time and to maintain the photoacoustic signal strength. 4.…”

“…Part of the challenge is the access to suitable chromophores and phantoms for proof-of-concept, testing, validation, and optimization. Despite recent advances on the study of phantom matrix materials for general photoacoustic (PA) system characterization and quality control, [8][9][10][11][12] for multiwavelength and quantitative PAI purposes further efforts are needed, with one of the crucial issues being finding suitable chromophores. 13,14 It is essential for these to be well-characterized, well-behaved, and stable.…”

“…22,23 Organic dyes can suffer from aggregation-related spectral shifts and often display transient and permanent photobleaching, e.g., cyanine-based dyes, 9,13,24 azobased 5 dyes, and basic dyes such as cresyl violet. 24 Gold nanoparticles can also exhibit changes in absorption after prolonged exposure, 9 with the added difficulty that their photoacoustic efficiency is not straightforward to model and characterize. 25,26 Inorganic absorbers such as Prussian blue and chloride salts such as CuCl 2 :2H 2 O and NiCl 2 :6H 2 O are highly photostable and have suitable spectra.…”

Multiscale structured germanium nanoripples as templates for bioactive surfaces

“…This method is less stressful for the mold than the usual thermal crosslinking process used for standard elastomeric materials. 36 The exposure was performed in two steps: rst, the sample was kept 180 s in nitrogen atmosphere, then 60 s in air. Aer curing, the PFPE lm was peeled off and cleaned with nitrogen ow.…”

The development and characterization of a novel yet simple 3D printed tool to facilitate phantom imaging of photoacoustic contrast agents

“…People have created a variety of customized phantoms using agarose, e.g., in the shape of the state of Texas [18] . This agarose is often doped with lipids [19] , inks [20] , titania [21] and/or acoustic scatterers such that it more accurately recapitulates human, i.e., a tissue-mimicking phantom. In another iteration, the contrast agent can be placed inside of plastic tubing that is then sealed inside of the agar [22] .…”