Quantitative blood oxygen saturation imaging using combined photoacoustics and acousto-optics

Hussain, Altaf; Petersen, Wilhelmina; Staley, Jacob; Hondebrink, Erwin; Steenbergen, Wiendelt

doi:10.1364/ol.41.001720

Cited by 43 publications

(24 citation statements)

References 16 publications

(16 reference statements)

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“…A limitation of the laser is the fixed output wavelength, which may preclude certain functional and molecular imaging applications, where spectral separation of photoacoustic signals are needed. However, spectral separation requires quantification of local fluence at each wavelength, which itself is challenging in deep tissue [47] and has only been partially addressed recently through acoustic-optics [48]. Nevertheless, our laser output is sufficient to pump an optical parametric oscillator and can potentially achieve multi-wavelength imaging.…”

Section: Human Imagingmentioning

confidence: 99%

Deep tissue photoacoustic computed tomography with a fast and compact laser system

Wang

et al. 2016

Biomed. Opt. Express

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Photoacoustic computed tomography (PACT) holds great promise for biomedical imaging, but wide-spread implementation is impeded by the bulkiness of flash-lamp-pumped laser systems, which typically weigh between 50 -200 kg, require continuous water cooling, and operate at a low repetition rate. Here, we demonstrate that compact lasers based on emerging diode technologies are well-suited for preclinical and clinical PACT. The diodepumped laser used in this study had a miniature footprint (13 × 14 × 7 cm 3 ), weighed only 1.6 kg, and outputted up to 80 mJ per pulse at 1064 nm. In vitro, the laser system readily provided over 4 cm PACT depth in chicken breast tissue. In vivo, in addition to high resolution, non-invasive brain imaging in living mice, the system can operate at 50 Hz, which enabled high-speed cross-sectional imaging of murine cardiac and respiratory function. The system also provided high quality, high-frame rate, and non-invasive three-dimensional mapping of arm, palm, and breast vasculature at multi centimeter depths in living human subjects, demonstrating the clinical viability of compact lasers for PACT.

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Section: Human Imagingmentioning

confidence: 99%

Deep tissue photoacoustic computed tomography with a fast and compact laser system

Wang

et al. 2016

Biomed. Opt. Express

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“…This has the effect of distorting the photoacoustic spectrum, commonly known as spectral coloring, which is a well-known confounding factor that compromises sO 2 measurement accuracy, and there is already a large amount of literature describing attempts to ameliorate it. [16][17][18][19][20][21][22][23] Despite this, an increasing number of publications are appearing that do not take spectral coloring into account, and yet assume that the estimates of sO 2 that are obtained are trustworthy. It is particularly concerning that articles are appearing in which these questionable estimates of sO 2 are being used to make judgments in preclinical [24][25][26][27][28][29][30][31][32][33][34][35][36] and even clinical studies.…”

Section: Introductionmentioning

confidence: 99%

Estimating blood oxygenation from photoacoustic images: can a simple linear spectroscopic inversion ever work?

et al. 2019

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Linear spectroscopic inversions, in which photoacoustic amplitudes are assumed to be directly proportional to absorption coefficients, are widely used in photoacoustic imaging to estimate blood oxygen saturation because of their simplicity. Unfortunately, they do not account for the spatially varying wavelengthdependence of the light fluence within the tissue, which introduces "spectral coloring," a potentially significant source of error. However, accurately correcting for spectral coloring is challenging, so we investigated whether there are conditions, e.g., sets of wavelengths, where it is possible to ignore the spectral coloring and still obtain accurate oxygenation measurements using linear inversions. Accurate estimates of oxygenation can be obtained when the wavelengths are chosen to (i) minimize spectral coloring, (ii) avoid ill-conditioning, and (iii) maintain a sufficiently high signal-to-noise ratio (SNR) for the estimates to be meaningful. It is not obvious which wavelengths will satisfy these conditions, and they are very likely to vary for different imaging scenarios, making it difficult to find general rules. Through the use of numerical simulations, we isolated the effect of spectral coloring from sources of experimental error. It was shown that using wavelengths between 500 nm and 1000 nm yields inaccurate estimates of oxygenation and that careful selection of wavelengths in the 620-to 920-nm range can yield more accurate oxygenation values. However, this is only achievable with a good prior estimate of the true oxygenation. Even in this idealized case, it was shown that considerable care must be exercised over the choice of wavelengths when using linear spectroscopic inversions to obtain accurate estimates of blood oxygenation. This suggests that for a particular imaging scenario, obtaining accurate and reliable oxygenation estimates using linear spectroscopic inversions requires careful modeling or experimental studies of that scenario, taking account of the instrumentation, tissue anatomy, likely sO 2 range, and image formation process.

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“…In order to compensate for spectral coloring and extract quantitative chromophore concentrations, we must have knowledge of the light propagation through the entire object. While non-invasive, non-destructive assessment of the light field in tissues in vivo is possible in principle [17]- [19], in practice it usually requires complex (and often expensive) additional instrumentation, hence the light fluence distribution is frequently modeled. Fortunately, there are a number of mathematical and numerical models that can be used to describe light propagation in optically absorbing and scattering media, reviewed comprehensively in [20].…”

Section: Introductionmentioning

confidence: 99%

Towards Quantitative Evaluation of Tissue Absorption Coefficients Using Light Fluence Correction in Optoacoustic Tomography

Brochu

Brunker

Joseph

et al. 2017

IEEE Trans. Med. Imaging

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Optoacoustic tomography is a fast developing imaging modality, combining the high contrast available from optical excitation of tissue with the high resolution and penetration depth of ultrasound detection. Light is subject to both absorption and scattering when traveling through tissue; adequate knowledge of tissue optical properties and hence the spatial fluence distribution is required to create an optoacoustic image that is directly proportional to chromophore concentrations at all depths. Using data from a commercial multispectral optoacoustic tomography (MSOT) system, we implemented an iterative optimization for fluence correction based on a finite-element implementation of the delta-Eddington approximation to the Radiative Transfer Equation (RTE). We demonstrate a linear relationship between the image intensity and absorption coefficients across multiple wavelengths and depths in phantoms. We also demonstrate improved feature visibility and spectral recovery at depth in phantoms and with in vivo measurements, suggesting our approach could in the future enable quantitative extraction of tissue absorption coefficients in biological tissue.

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Quantitative blood oxygen saturation imaging using combined photoacoustics and acousto-optics

Cited by 43 publications

References 16 publications

Deep tissue photoacoustic computed tomography with a fast and compact laser system

Deep tissue photoacoustic computed tomography with a fast and compact laser system

Estimating blood oxygenation from photoacoustic images: can a simple linear spectroscopic inversion ever work?

Towards Quantitative Evaluation of Tissue Absorption Coefficients Using Light Fluence Correction in Optoacoustic Tomography

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