Performance evaluation of mesoscopic photoacoustic imaging

Abstract

Photoacoustic mesoscopy visualises vascular architecture and associated tissue structures at high resolution at up to 3 mm depth. The technique has shown promise in both preclinical and clinical imaging studies, with possible applications in oncology and dermatology, however, the accuracy and precision of photoacoustic mesoscopy has not been well established. Here, we present a performance evaluation of a commercial photoacoustic mesoscopy system for imaging vascular structures. Typical artefact types are first highlighted and limitations due to non-isotropic illumination and detection are evaluated with respect to rotation, angularity, and depth of the target. Then, using tailored phantoms and mouse models we demonstrate high system precision, with acceptable coefficients of variation (COV) between repeated scans (short term (1h): COV=1.2%; long term (25 days): COV=9.6%), from target repositioning (without: COV=1.2%, with: COV=4.1%), or from varyingin vivouser experience (experienced: COV=15.9%, unexperienced: COV=20.2%). While our findings support the robustness of the technique, they also underscore the general challenges of limited field-of-view photoacoustic systems in accurately imaging vessel-like structures, thereby guiding users to correctly interpret biologically-relevant information.

Moving Beyond Simulation: Data-Driven Quantitative Photoacoustic Imaging Using Tissue-Mimicking Phantoms

“…5% error of the optical absorption coefficient and simulated initial pressure distribution. In conjunction with the 10%-20% error we determined for the DIS system based on cross-reference with time-resolved near-infrared spectroscopy [27], our reference optical material properties are subject to a standard error in the order of 20%. In future work, these uncertainties could be incorporated into model training by using Bayesian deep learning methods.…”

“…Briefly, 83.80 g mineral oil (Sigma Aldrich-330779-1L) was used as a base. 25.14 g polystyrene-blockpoly(ethylene-ran-butylene)-block-polystyrene (SEBS, Sigma Aldrich 200557-250G) as the polymer and 2.09 g butylated hydroxytoluene (HT, Sigma Aldrich W218405-1KG-K) as an antioxidant was added to the mineral oil base, which was heated to 150 • C and poured into a mould, for details see [25] and [27]). Different concentrations of titanium dioxide (TiO 2 , Sigma Aldrich 232033-100g) and alcohol-soluble nigrosin (Sigma Aldrich 211680-100G) were used to tune µ ′ s and µ a respectively.…”

Photoacoustic imaging for cutaneous melanoma assessment: a comprehensive review

“…In recent years, there has been a growing interest among various companies in the development and commercialization of PAI systems for medical applications 145 , 285 . Among them are iThera Medical GmbH, 105 , 130 , 180 , 286 – 297 FUJIFILM VisualSonics, 135 , 171 , 187 , 298 ENDRA Life Sciences Inc., 299 – 303 TomoWave Laboratories, 304 – 307 and Seno Medical Instruments 308 , 309 . Although there exist commercial systems for skin imaging, there has not been any customized clinical system for melanoma imaging applications.…”

Photoacoustic imaging for investigating tumor hypoxia: a strategic assessment

“…Label free imaging was used to investigate tumor hypoxia in multiple types of cancers [14,[86][87][88]90]. This method has also been effective in assessing the distribution of oxygen within a solid tumor, in which label free PAI has detailed the tumor core to be hypoxic, whereas the 'rim' of the tumor was well oxygenated.…”

“…This method has also been effective in assessing the distribution of oxygen within a solid tumor, in which label free PAI has detailed the tumor core to be hypoxic, whereas the 'rim' of the tumor was well oxygenated. The consensus arrived at from these label free studies is tumor tissue has oxygenation levels that are measurably different from healthy tissue [14,[86][87][88] and higher fluctuations are seen in oxygen saturation in tumor models with higher disease aggressiveness [90]. Label free imaging has also been shown to be responsive to changes in tumor oxygenation upon external application of oxygen [14].…”