Ultrasound-modulated optical computed tomography of biological tissues

Abstract

An optical imaging technique called ultrasound-modulated optical computed tomography is demonstrated for tomographic imaging of biological tissues. Ultrasound-modulated optical signals are extracted from scattered light to provide projection data for the image reconstruction. A filtered back-projection algorithm is implemented to reconstruct an image reflecting optical tissue properties from angular and linear scans of an ultrasonic beam across a sample. This reconstruction-based imaging technique provides a way to obtain images of cross sections containing the scanned ultrasonic axis in biological tissues, which enables three-dimensional ultrasound-modulated optical imaging. The technique combines the contrast advantage of optical waves and the resolution advantage of ultrasonic waves.

High-resolution ultrasound-modulated optical tomography in biological tissues

“…A CCD camera that provides parallel speckle detection 8,9,14 was used to produce a better signal-to-noise ratio than a single square-law detector. To obtain resolution along the ultrasonic axis, several groups of scientists explored various techniques, including an ultrasound frequency sweep, 7 computer tomography, 15 and tracking of ultrasound pulses 11 or short bursts. 13 The pulsed ultrasound approaches provide direct resolution along the ultrasonic axis and are more compatible with conventional ultrasound imaging.…”

Real-Time Monitoring of High-Intensity Focused Ultrasound Lesion Formation Using Acousto-Optic Sensing

“…The feasibility of this reflection configuration for AO imaging has been successfully demonstrated (Lev et al 2000;Granot et al 2001;Li and Wang 2004;Sakadzic and Wang 2004;Kothapalli and Wang 2009). However, it should be noted that the background (''untagged'') photon flux is higher in a reflection geometry than in a transillumination geometry, which makes detection of the tagged photons emanating from deep within the tissue more challenging.…”

Ultrasound-mediated optical tomography: a review of current methods

“…The UOT signal detected can be considered as an integration of many incremental contributions from different points along the ultrasound axis. This is conceptually similar to CT imaging and, by rotating and translating the object and recording multiple projection angles, Radon transform methods could be used to make a reconstruction of the object [18].…”

“…The potential application areas of the technique overlap with those for DOT; for instance, for breast cancer imaging, where the current modalities of mammography and ultrasound are not sufficient owing to the use of ionizing radiation and/or the lack of contrast or signal specificity between the healthy tissues and the disease tissues [16]. Besides bulk tissue tomography, there are also other niche applications in the subsurface detection of tumours, for instance in the neck [16], or for brain imaging [17,18] to monitor the local oxygenation level and to allow the imaging of brain tumours and injuries. Further applications have been suggested, for instance in the assessment of osteoporosis [19], and more recently high-resolution UOT has been used for detecting sentinel lymph nodes that have been labelled with an exogenous optical absorber [20].…”