Ultrasound-on-chip platform for medical imaging, analysis, and collective intelligence.

Over the past half-century, ultrasound imaging has become a key technology for assessing an ever-widening range of medical conditions at all stages of life. Despite ultrasound's proven value, expensive systems that require domain expertise in image acquisition and interpretation have limited its broad adoption. The proliferation of portable and low-cost ultrasound imaging can improve global health and also enable broad clinical and academic studies with great impact on the fields of medicine.

Fast-start escape performance across temperature and salinity gradients in mummichog Fundulus heteroclitus.

Fast-start predator-escape performance of mummichogs Fundulus heteroclitus was tested across field-informed variation in temperature (24, 30 and 36°C) and salinity (2, 12 and 32 ppt). Performance was similar across temperatures and salinities when fish were allowed to acclimate to these conditions. However, when mummichogs experienced acute temperature changes, performance exhibited thermal dependence in two contrasting ways.

Cross-validation of interferometric synthetic aperture microscopy and optical coherence tomography.

Computationally reconstructed interferometric synthetic aperture microscopy is coregistered with optical coherence tomography (OCT) focal plane data to provide quantitative cross validation with OCT. This is accomplished through a qualitative comparison of images and a quantitative analysis of the width of the point-spread function in simulation and experiment. The width of the ISAM point-spread function is seen to be independent of depth, in contrast to OCT.

Imaging gold nanorods in excised human breast carcinoma by spectroscopic optical coherence tomography.

Plasmon-resonant gold nanorods (GNRs) can serve as imaging agents for spectroscopic optical coherence tomography (SOCT). The aspect ratio of the GNRs are adjusted for maximum absorption in the far red to create a partial spectral overlap with the low-wavelength edge of the near-infrared SOCT imaging band. The spectroscopic absorption profile of the GNRs is incorporated into a depth-resolved algorithm for mapping the relative GNR density within OCT images.

Magnetomotive nanoparticle transducers for optical rheology of viscoelastic materials.

The availability of a real-time non-destructive modality to interrogate the mechanical properties of viscoelastic materials would facilitate many new investigations. We introduce a new optical method for measuring elastic properties of samples which employs magnetite nanoparticles as perturbative agents. Magnetic nanoparticles distributed in silicone-based samples are displaced upon probing with a small external magnetic field gradient and depth-resolved optical coherence phase shifts allow for the tracking of scatterers in the sample with nanometer-scale sensitivity.

Detecting intrinsic scattering changes correlated to neuron action potentials using optical coherence imaging.

We demonstrate how optical coherence imaging techniques can detect intrinsic scattering changes that occur during action potentials in single neurons. Using optical coherence tomography (OCT), an increase in scattering intensity from neurons in the abdominal ganglion of Aplysia californica is observed following electrical stimulation of the connective nerve. In addition, optical coherence microscopy (OCM), with its superior transverse spatial resolution, is used to demonstrate a direct correlation between scattering intensity changes and membrane voltage in single cultured Aplysia bag cell neurons during evoked action potentials.

High-speed processing architecture for spectral-domain optical coherence microscopy.

Optical coherence microscopy (OCM) is an interferometric technique that combines principles of confocal microscopy and optical coherence tomography (OCT) to obtain high-resolution en face images. Axial and lateral resolutions of several microns can be achieved using OCM depending on the numerical aperture (NA) of the objective and sample properties. We address the computational complexity that is inherent in spectral-domain OCM systems that limits its real-time capability as a microscope.

Real-time interferometric synthetic aperture microscopy.

An interferometric synthetic aperture microscopy (ISAM) system design with real-time 2D cross-sectional processing is described in detail. The system can acquire, process, and display the ISAM reconstructed images at frame rates of 2.25 frames per second for 512 X 1024 pixel images.

Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy.

Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images.

Nonparaxial vector-field modeling of optical coherence tomography and interferometric synthetic aperture microscopy.

A large-aperture, electromagnetic model for coherent microscopy is presented and the inverse scattering problem is solved. Approximations to the model are developed for near-focus and far-from-focus operations. These approximations result in an image-reconstruction algorithm consistent with interferometric synthetic aperture microscopy (ISAM): this validates ISAM processing of optical-coherence-tomography and optical-coherence-microscopy data in a vectorial setting.

Autocorrelation artifacts in optical coherence tomography and interferometric synthetic aperture microscopy.

Interferometric synthetic aperture microscopy processing of optical coherence tomography data has been shown to allow computational focusing of en face planes that have traditionally been regarded as out of focus. It is shown that this focusing of the image also produces a defocusing effect in autocorrelation artifacts resulting from Fourier-domain data collection. This effect is verified experimentally and through simulation.

Inverse scattering for frequency-scanned full-field optical coherence tomography.

Full-field optical coherence tomography (OCT) is able to image an entire en face plane of scatterers simultaneously, but typically the focus is scanned through the volume to acquire three-dimensional structure. By solving the inverse scattering problem for full-field OCT, we show it is possible to computationally reconstruct a three-dimensional volume while the focus is fixed at one plane inside the sample. While a low-numerical-aperture (NA) OCT system can tolerate defocus because the depth of field is large, for high NA it is critical to correct for defocus.

Interferometric synthetic aperture microscopy.

State-of-the-art methods in high-resolution three-dimensional optical microscopy require that the focus be scanned through the entire region of interest. However, an analysis of the physics of the light-sample interaction reveals that the Fourier-space coverage is independent of depth. Here we show that, by solving the inverse scattering problem for interference microscopy, computed reconstruction yields volumes with a resolution in all planes that is equivalent to the resolution achieved only at the focal plane for conventional high-resolution microscopy.

Inverse scattering for high-resolution interferometric microscopy.

We extend the applicability of inverse scattering for optical coherence tomography (OCT) to the case of high numerical aperture focusing optics. We include the effects of tight focusing so that the approach is applicable to any interferometric microscopy method. The applicability to modalities, such as OCT and optical coherence microscopy, enables computed reconstruction of three-dimensional volumes from en face temporal ranging data.

Inverse scattering for rotationally scanned optical coherence tomography.

Optical coherence tomography of luminal structures, such as for intravascular or gastrointestinal imaging, is performed by using a fiber-optic catheter as a beam-delivery probe. The interrogating beam is scanned angularly by rotating the fiber around a fixed central axis. Because the beam is focused only at a fixed distance from the center of the fiber, only scatterers near this distance are resolved.

Three-dimensional optical coherence tomography of the embryonic murine cardiovascular system.

Optical coherence tomography (OCT) is an emerging high-resolution real-time biomedical imaging technology that has potential as a novel investigational tool in developmental biology and functional genomics. In this study, murine embryos and embryonic hearts are visualized with an OCT system capable of 2-microm axial and 15-microm lateral resolution and with real-time acquisition rates. We present, to our knowledge, the first sets of high-resolution 2- and 3-D OCT images that reveal the internal structures of the mammalian (murine) embryo (E10.

Inverse scattering for optical coherence tomography.

Inverse scattering theory for optical coherence tomography (OCT) is developed. The results are used to produce algorithms to resolve three-dimensional object structure, taking into account the finite beam width, diffraction, and defocusing effects. The resolution normally achieved only in the focal plane of the OCT system is shown to be available for all illuminated depths in the object without moving the focal plane.

Spectroscopic spectral-domain optical coherence microscopy.

The spectroscopic content within optical coherence tomography (OCT) data can provide a wealth of information. Spectroscopic OCT methods are frequently limited by time-frequency trade-offs that limit high spectral and spatial resolution simultaneously. We present spectroscopic spectral-domain optical coherence microscopy performed with a multimodality microscope.

Speckle reduction by I-divergence regularization in optical coherence tomography.

For optical coherence tomography (OCT), ultrasound, synthetic-aperture radar, and other coherent ranging methods, speckle can cause spurious detail that detracts from the utility of the image. It is a problem inherent to imaging densely scattering objects with limited bandwidth. Using a method of regularization by minimizing Csiszar's I-divergence measure, we derive a method of speckle minimization that produces an image that both is consistent with the known data and extrapolates additional detail based on constraints on the magnitude of the image.

Deconvolution methods for mitigation of transverse blurring in optical coherence tomography.

Imaging resolution in optical coherence tomography (OCT) is a key determinant for acquiring clinically useful optical biopsies of tissues. In contrast to light or confocal microscopy, the axial and transverse resolutions in OCT are independent and each can be analyzed individually. A method for mitigating transverse blurring and the apparent loss of transverse resolution in OCT by means of Gaussian beam deconvolution is presented.

Optical biopsy of lymph node morphology using optical coherence tomography.

Optical diagnostic imaging techniques are increasingly being used in the clinical environment, allowing for improved screening and diagnosis while minimizing the number of invasive procedures. Diffuse optical tomography, for example, is capable of whole-breast imaging and is being developed as an alternative to traditional X-ray mammography. While this may eventually be a very effective screening method, other optical techniques are better suited for imaging on the cellular and molecular scale.

The human fear-circuitry and fear-induced fainting in healthy individuals--the paleolithic-threat hypothesis.

The Paleolithic-Threat hypothesis reviewed here posits that habitual efferent fainting can be traced back to fear-induced allelic polymorphisms that were selected into some genomes of anatomically, mitochondrially, and neurally modern humans (Homo sapiens sapiens) in the Mid-Paleolithic because of the survival advantage they conferred during periods of inescapable threat. We posit that during Mid-Paleolithic warfare an encounter with "a stranger holding a sharp object" was consistently associated with threat to life. A heritable hardwired or firm-wired (prepotentiated) predisposition to abruptly increase vagal tone and collapse flaccidly rather than freeze or attempt to flee or fight in response to an approaching sharp object, a minor injury, or the sight of blood, may have evolved as an alternative stress-induced fear-circuitry response.

The clenching-grinding spectrum and fear circuitry disorders: clinical insights from the neuroscience/paleoanthropology interface.

This review discusses the clenching-grinding spectrum from the neuropsychiatric/neuroevolutionary perspective. In neuropsychiatry, signs of jaw clenching may be a useful objective marker for detecting or substantiating a self-report of current subjective emotional distress. Similarly, accelerated tooth wear may be an objective clinical sign for detecting, or substantiating, long-lasting anxiety.