Ultrasound-mediation of self-illuminating reporters improves imaging resolution in optically scattering media

Ahmad, Junaid and Jayet, Baptiste and Hill, Philip J. and Mather, Melissa L. and Dehghani, Hamid and Morgan, Stephen P. (2018) Ultrasound-mediation of self-illuminating reporters improves imaging resolution in optically scattering media. Biomedical Optics Express, 9 (4). pp. 1664-1679. ISSN 2156-7085

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Abstract

In vivo imaging of self-illuminating bio-and chemiluminescent reporters is used to observe the physiology of small animals. However, strong light scattering by biological tissues results in poor spatial resolution of the optical imaging, which also degrades the quantitative accuracy. To overcome this challenging problem, focused ultrasound is used to modulate the light from the reporter at the ultrasound frequency. This produces an ultrasound switchable light ‘beacon’ that reduces the influence of light scattering in order to improve spatial resolution. The experimental results demonstrate that apart from light modulation at the ultrasound frequency (AC signal at 3.5 MHz), ultrasound also increases the DC intensity of the reporters. This is shown to be due to a temperature rise caused by insonification that was minimized to be within acceptable mammalian tissue safety thresholds by adjusting the duty cycle of the ultrasound. Line scans of bio-and chemiluminescent objects embedded within a scattering medium were obtained using ultrasound modulated (AC) and ultrasound enhanced (DC) signals. Lateral resolution is improved by a factor of 12 and 7 respectively, as compared to conventional CCD imaging. Two chemiluminescent sources separated by ~10mm at ~20 mm deep inside a 50 mm thick chicken breast have been successfully resolved with an average signal-to-noise ratio of approximately 8-10 dB.

Item Type: Article
Schools/Departments: University of Nottingham, UK > Faculty of Engineering
University of Nottingham, UK > Faculty of Science > School of Biosciences
Identification Number: https://doi.org/10.1364/BOE.9.001664
Depositing User: Eprints, Support
Date Deposited: 21 Feb 2018 15:39
Last Modified: 26 Jun 2018 12:43
URI: http://eprints.nottingham.ac.uk/id/eprint/49923

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