296 research outputs found
Prediction and near-field observation of skull-guided acoustic waves
Ultrasound waves propagating in water or soft biological tissue are strongly
reflected when encountering the skull, which limits the use of ultrasound-based
techniques in transcranial imaging and therapeutic applications. Current
knowledge on the acoustic properties of the cranial bone is restricted to
far-field observations, leaving its near-field properties unexplored. We report
on the existence of skull-guided acoustic waves, which was herein confirmed by
near-field measurements of optoacoustically-induced responses in ex-vivo murine
skulls immersed in water. Dispersion of the guided waves was found to
reasonably agree with the prediction of a multilayered flat plate model. It is
generally anticipated that our findings may facilitate and broaden the
application of ultrasound-mediated techniques in brain diagnostics and therapy.Comment: 7 pages, 5 figures, appendix with 2 figure
Simultaneous control of volumetric light distribution through turbid media using real-time three-dimensional optoacoustic feedback
Focusing light through turbid media presents a highly fascinating challenge
in modern biophotonics. The unique capability of optoacoustics for high
resolution imaging of light absorption contrast in deep tissues can provide a
natural and efficient feedback to control light delivery in scattering medium.
While basic feasibility of using optoacoustic readings as a feedback mechanism
for wavefront shaping has been recently reported, the suggested approaches may
require long acquisition times making them challenging to be translated into
realistic tissue environments. In an attempt to significantly accelerate
dynamic wavefront shaping capabilities, we present here a feedback-based
approach using real-time three-dimensional optoacoustic imaging assisted with
genetic-algorithm-based optimization. The new technique offers robust
performance in the presence of noisy measurements and can simultaneously
control the scattered wave field in an entire volumetric region.Comment: 4 pages, 3 figure
Visual Quality Enhancement in Optoacoustic Tomography using Active Contour Segmentation Priors
Segmentation of biomedical images is essential for studying and
characterizing anatomical structures, detection and evaluation of pathological
tissues. Segmentation has been further shown to enhance the reconstruction
performance in many tomographic imaging modalities by accounting for
heterogeneities of the excitation field and tissue properties in the imaged
region. This is particularly relevant in optoacoustic tomography, where
discontinuities in the optical and acoustic tissue properties, if not properly
accounted for, may result in deterioration of the imaging performance.
Efficient segmentation of optoacoustic images is often hampered by the
relatively low intrinsic contrast of large anatomical structures, which is
further impaired by the limited angular coverage of some commonly employed
tomographic imaging configurations. Herein, we analyze the performance of
active contour models for boundary segmentation in cross-sectional optoacoustic
tomography. The segmented mask is employed to construct a two compartment model
for the acoustic and optical parameters of the imaged tissues, which is
subsequently used to improve accuracy of the image reconstruction routines. The
performance of the suggested segmentation and modeling approach are showcased
in tissue-mimicking phantoms and small animal imaging experiments.Comment: Accepted for publication in IEEE Transactions on Medical Imagin
Low-cost optoacoustics? Prospects for miniaturizing and democratizing optoacoustic imaging systems in biomedical research and the clinics
Please click Additional Files below to see the full abstract
LongâTerm Imaging of Wound Angiogenesis with Large Scale Optoacoustic Microscopy
Wound healing is a well-coordinated process, necessitating efficient formation of new blood vessels. Vascularization defects are therefore a major risk factor for chronic, non-healing wounds. The dynamics of mammalian tissue revascularization, vessel maturation, and remodeling remain poorly understood due to lack of suitable in vivo imaging tools. A label-free large-scale optoacoustic microscopy (LSOM) approach is developed for rapid, non-invasive, volumetric imaging of tissue regeneration over large areas spanning up to 50 mm with a depth penetration of 1.5 mm. Vascular networks in dorsal mouse skin and full-thickness excisional wounds are imaged with capillary resolution during the course of healing, revealing previously undocumented views of the angiogenesis process in an unperturbed wound environment. Development of an automatic analysis framework enables the identification of key features of wound angiogenesis, including vessel length, diameter, tortuosity, and angular alignment. The approach offers a versatile tool for preclinical research in tissue engineering and regenerative medicine, empowering label-free, longitudinal, high-throughput, and quantitative studies of the microcirculation in processes associated with normal and impaired vascular remodeling, and analysis of vascular responses to pharmacological interventions in vivo
- âŠ