Diffuse optical tomography to investigate the newborn brain

Lee, Chuen Wai; Cooper, Robert J.; Austin, Topun

doi:10.1038/pr.2017.107

Cited by 48 publications

(43 citation statements)

References 83 publications

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“…Despite the excellent results obtained in this phantom study it is still difficult to predict whether this hybrid imaging modality will perform as well in vivo where further optimization strategies tailored to the high complexity and heterogeneity of the target tissue might be needed . Future steps will include the construction of the prototype sketched in Figure to examine the applicability of our multi‐modal system for the early detection of cerebral ischemia in preterm infants.…”

Section: Discussionmentioning

confidence: 99%

“…To each voxel, or position r = (x, y, z), in the volume is assigned an absorption coefficient μ a , λ ( r ) and a reduced scattering coefficient

μ_{s, λ}^{'} ((), r)

for every wavelength λ . We assume that the reduced scattering coefficient

μ_{s, λ}^{'} ((), r)

does not significantly change across V , while heterogeneities in μ a , λ ( r ) can be significant, due to spatial variations in the concentration of the main chromophore hemoglobin . The aim of this study is to use OA imaging to retrieve the spectra of the absorption coefficients μ a , λ at the positions of the submillimetric vessel‐like absorbers that cannot be resolved in NIROT reconstructions.…”

Section: Spectral Correction Of 2d Oa Images By Means Of Nirot: Theorymentioning

confidence: 99%

“…One problem in the reconstruction is the lack of a unique set of solutions: μ a , λ and

μ_{s, λ}^{'}

have an interchangeable influence on the simulated data, so that many different configurations of optical properties can explain the recorded measurements . Here, this effect is partially reduced by implementing the assumption that spatial variations in

μ_{s, λ}^{'}

are much lower than variations in μ a , λ , which allows the choice of a regularization strength, determined empirically, that is 100 times stronger for

μ_{s, λ}^{'}

than for μ a , λ .…”

Section: Spectral Correction Of 2d Oa Images By Means Of Nirot: Theorymentioning

confidence: 99%

“…Cerebral ischemia is a key initiating factor for white matter injury , which has become the dominant pathology in the premature brain and is a major reason for long‐term neurodevelopmental impairments . Reconstructing the optical properties of the infant brain by means of near‐infrared optical tomography (NIROT) has been investigated, based on the technical progress achieved in near‐infrared spectroscopy (NIRS) . This article examines the feasibility of employing NIROT to estimate the light fluence at the positions of vessels imaged by OA.…”

Section: Introductionmentioning

confidence: 99%

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Spectral correction for handheld optoacoustic imaging by means of near‐infrared optical tomography in reflection mode

Ulrich

Ahnen²,

Akarçay

et al. 2018

Journal of Biophotonics

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In vivo imaging of tissue/vasculature oxygen saturation levels is of prime interest in many clinical applications. To this end, the feasibility of combining two distinct and complementary imaging modalities is investigated: optoacoustics (OA) and near-infrared optical tomography (NIROT), both operating noninvasively in reflection mode. Experiments were conducted on two optically heterogeneous phantoms mimicking tissue before and after the occurrence of a perturbation. OA imaging was used to resolve submillimetric vessel-like optical absorbers at depths up to 25 mm, but with a spectral distortion in the OA signals. NIROT measurements were utilized to image perturbations in the background and to estimate the light fluence inside the phantoms at the wavelength pair (760 nm, 830 nm). This enabled the spectral correction of the vessel-like absorbers' OA signals: the error in the ratio of the absorption coefficient at 830 nm to that at 760 nm was reduced from 60%-150% to 10%-20%. The results suggest that oxygen saturation (SO ) levels in arteries can be determined with<10% error and furthermore, that relative changes in vessels' SO can be monitored with even better accuracy. The outcome relies on a proper identification of the OA signals emanating from the studied vessels.

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Section: Discussionmentioning

confidence: 99%

“…To each voxel, or position r = (x, y, z), in the volume is assigned an absorption coefficient μ a , λ ( r ) and a reduced scattering coefficient

μ_{s, λ}^{'} ((), r)

for every wavelength λ . We assume that the reduced scattering coefficient

μ_{s, λ}^{'} ((), r)

Section: Spectral Correction Of 2d Oa Images By Means Of Nirot: Theorymentioning

confidence: 99%

“…One problem in the reconstruction is the lack of a unique set of solutions: μ a , λ and

μ_{s, λ}^{'}

μ_{s, λ}^{'}

are much lower than variations in μ a , λ , which allows the choice of a regularization strength, determined empirically, that is 100 times stronger for

μ_{s, λ}^{'}

than for μ a , λ .…”

Section: Spectral Correction Of 2d Oa Images By Means Of Nirot: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spectral correction for handheld optoacoustic imaging by means of near‐infrared optical tomography in reflection mode

Ulrich

Ahnen²,

Akarçay

et al. 2018

Journal of Biophotonics

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show abstract

“…Also, because of the thinner scalp and skull compared to adults, the fNIRS cerebral sensitivity is great in infants. These advantages have led to the adoption of fNIRS for a vast range of studies of both typical and atypical neurodevelopment ([42][43][44]), including the development of object and face processing, number processing, language acquisition, social communication, and neuromotor development. Studies of atypical functional development have focused mainly on attention deficit hyperactivity disorder and autism spectrum disorder.…”

Section: Introductionmentioning

confidence: 99%

Functional Near Infrared Spectroscopy: Enabling routine functional brain imaging

Yücel

Selb

Huppert

et al. 2017

Current Opinion in Biomedical Engineering

171

134

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Functional Near-Infrared Spectroscopy (fNIRS) maps human brain function by measuring and imaging local changes in hemoglobin concentrations in the brain that arise from the modulation of cerebral blood flow and oxygen metabolism by neural activity. Since its advent over 20 years ago, researchers have exploited and continuously advanced the ability of near infrared light to penetrate through the scalp and skull in order to non-invasively monitor changes in cerebral hemoglobin concentrations that reflect brain activity. We review recent advances in signal processing and hardware that significantly improve the capabilities of fNIRS by reducing the impact of confounding signals to improve statistical robustness of the brain signals and by enhancing the density, spatial coverage, and wearability of measuring devices respectively. We then summarize the application areas that are experiencing rapid growth as fNIRS begins to enable routine functional brain imaging.

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Construction and validation of a database of head models for functional imaging of the neonatal brain

Collins-Jones

Poppe

Billing

et al. 2020

Human Brain Mapping

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The neonatal brain undergoes dramatic structural and functional changes over the last trimester of gestation. The accuracy of source localisation of brain activity recorded from the scalp therefore relies on accurate age‐specific head models. Although an age‐appropriate population‐level atlas could be used, detail is lost in the construction of such atlases, in particular with regard to the smoothing of the cortical surface, and so such a model is not representative of anatomy at an individual level. In this work, we describe the construction of a database of individual structural priors of the neonatal head using 215 individual‐level datasets at ages 29–44 weeks postmenstrual age from the Developing Human Connectome Project. We have validated a method to segment the extra‐cerebral tissue against manual segmentation. We have also conducted a leave‐one‐out analysis to quantify the expected spatial error incurred with regard to localising functional activation when using a best‐matching individual from the database in place of a subject‐specific model; the median error was calculated to be 8.3 mm (median absolute deviation 3.8 mm). The database can be applied for any functional neuroimaging modality which requires structural data whereby the physical parameters associated with that modality vary with tissue type and is freely available at http://www.ucl.ac.uk/dot-hub.

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Diffuse optical tomography to investigate the newborn brain

Cited by 48 publications

References 83 publications

Spectral correction for handheld optoacoustic imaging by means of near‐infrared optical tomography in reflection mode

Spectral correction for handheld optoacoustic imaging by means of near‐infrared optical tomography in reflection mode

Functional Near Infrared Spectroscopy: Enabling routine functional brain imaging

Construction and validation of a database of head models for functional imaging of the neonatal brain

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