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PubMedDate not supplied

[Possibilities of using telemedicine in preoperative examination of the lens nucleus density].

The MPEG-4 algorithm applicable to compression of video-images of the anterior eye segment and JPEG-2000 applicable to compression of static images of the lens and retina under the conditions of mydriasis were used to enable the telemedicine consultations. The compiled compression files were sent to the institute's E-Mail address by means of a voice modem through an analogue telephone line. The pixel structures of non-compression and compression images of the anterior eye segment and lenses were comparatively studied. The deviations of images' optic density versus non-compression images were found to be below or equal to 2.7%, thus, they can be attributed to a static error. The quantitative colorimetry of images was used, on the basis of a software-based color-regulating filter, to determine the lens-nucleus density and cataract-maturity degree. The differences between values of the green-canal brightness were found within the RGB model before and after the application of the filter in the posterior cortical strata and in the anterior lens-nucleus portion, which provided for classifying 6 stages of the lens-nucleus density and cataract maturity.

Algorithms↗
PubMed2004

Imaging parallel fiber and climbing fiber responses and their short-term interactions in the mouse cerebellar cortex in vivo.

A major question in the study of cerebellar cortical function is how parallel fiber and climbing fiber inputs interact to shape information processing. Emphasis has been placed on the long-term effects due to conjunctive stimulation of climbing fibers and parallel fibers. Much less emphasis has been placed on short-term interactions and their spatial nature. To address this question the responses to parallel fiber and climbing fiber inputs and their short-term interaction were characterized using optical imaging with Neutral Red in the anesthetized mouse in vivo. Electrical stimulation of the cerebellar surface evoked an increase in fluorescence consisting of a transverse optical beam. The linear relationship between the optical responses and stimulus parameters, high spatial resolution and close coupling to the electrophysiological recordings show the utility of this imaging methodology. The majority of the optical response was due to activation of postsynaptic alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate (AMPA) and metabotropic glutamate receptors with a minor contribution from the presynaptic parallel fibers. Stimulation of the inferior olive evoked parasagittal bands that were abolished by blocking AMPA glutamate receptors. Conjunctive stimulation of the cerebellar surface and inferior olive resulted in inhibition of the climbing fiber evoked optical responses. This lateral inhibition of the parasagittal bands extended out from both sides of an activated parallel fiber beam and was mediated by GABA(A) but not GABA(B) receptors. One hypothesized role for lateral inhibition of this type is to spatially focus the interactions between parallel fiber and climbing fiber input on Purkinje cells. In summary optical imaging with Neutral Red permitted visualization of cerebellar cortical responses to parallel fiber and climbing fiber activation. The GABA(A) dependent lateral inhibition of the climbing fiber evoked parasagittal bands by parallel fiber stimulation shows that cerebellar interneurons play a short-term role in shaping the responses of Purkinje cells to climbing fiber input.

Animals↗
PubMed2006

Diffuse optical tomography system to image brain activation with improved spatial resolution and validation with functional magnetic resonance imaging.

Although most current diffuse optical brain imaging systems use only nearest- neighbor measurement geometry, the spatial resolution and quantitative accuracy of the imaging can be improved through the collection of overlapping sets of measurements. A continuous-wave diffuse optical imaging system that combines frequency encoding with time-division multiplexing to facilitate overlapping measurements of brain activation is described. Phantom measurements to confirm the expected improvement in spatial resolution and quantitative accuracy are presented. Experimental results showing the application of this instrument for imaging human brain activation are also presented. The observed improvement in spatial resolution is confirmed by functional magnetic resonance imaging.

Brain↗
PubMed2006

A method for chorioretinal oxygen tension measurement.

PURPOSE: To report an optical imaging system that was developed to measure oxygen tension (pO2) in the chorioretinal vasculatures. The feasibility of the system for the measurement of changes in pO2 separately in the retinal and choroidal vasculatures was established in rat eyes by varying the fraction of inspired oxygen and inhibiting nitric oxide activity. METHODS: Our optical section phosphorescence imaging system was modified to provide quantitative measurements of pO2 separately in the retinal and choroidal vasculatures. A narrow laser line was projected at an angle on the retina after intravenous injection of an oxygen-sensitive probe (Pd-porphyrin), and phosphorescence emission was imaged. A frequency-domain approach allowed measurements of the phosphorescence lifetime by varying the phase relationship between the modulated excitation laser light and sensitivity of the imaging camera. Chorioretinal pO2 was measured while varying the fraction of inspired oxygen and during intravenous infusion of Nomega-nitro-L-arginine (Nomega-NLA), a nonselective nitric oxide synthase inhibitor. RESULTS: The systemic arterial pO2 varied according to the fraction of inspired oxygen. The pO2 in the retinal and choroidal vasculatures increased as the fraction of inspired oxygen was increased. Compared with baseline, choroidal pO2 decreased during infusion of Nomega-NLA, whereas the pO2 in the retinal vasculatures remained relatively unchanged. The choroidal pO2 decreased markedly with each incremental increase in Nomega-NLA infusion rate, in the range 1-6 mg/min, and there was no additional change in the choroidal pO2 at Nomega-NLA infusion rates above 6 mg/min. CONCLUSIONS: An optical method combining pO2 phosphorescence imaging with chorioretinal optical sectioning was established that can potentially be applied for better understanding of retinal and choroidal oxygen dynamics in physiologic and pathologic states.

Animals↗
PubMed1999

[Application of the simplified method of optic recording for mapping focuses of the neuronal activity in the somatosensory cortex of the white rats].

In rats, a differential signal was used for evoking an optical image in the barrel-field zone which represented a difference between cortical images during the control and the stimulation periods. After a subtraction of averaged sequences of frames, an image of spots reflecting a probable location of activated groups of neurones was obtained. Natural low frequency stimulation of vibrissae is supposed to be the most effective. The method of intrinsic optical activity imaging can be applied for preliminary mapping of cortical zones.

Animals↗
PubMed1999

Optical recording of cortical activity after in vitro perfusion of cerebral arteries with a voltage-sensitive dye.

Cortical neuronal architecture and connectivity can be analyzed with high-resolution optical imaging after staining the in vitro isolated guinea pig brain preparation by circulating the voltage-sensitive dye RH795 via the arterial system. To establish this new technique, electrical field potentials evoked in the piriform and entorhinal cortices by lateral olfactory tract stimulation were correlated to the optical signal. The depth analysis of the optical response was performed by evaluating the contribution of the mono- and poly-synaptic components of the signal generated in different layers after applying a pair-pulse stimulation protocol. The tangential propagation of neuronal activity in olfactory cortices was evaluated by gathering several 4.2 x 4.2 mm images recorded from adjacent cortical areas. The real-time optical imaging technique applied to the isolated guinea pig brain can be successfully utilized to study the integrative properties of cortical neurons ensembles.

Animals↗
PubMed1996

Imaging calcium dynamics in dendritic spines.

Recent advances in optical imaging technology have enabled the measurement of Ca2+ dynamics in individual synaptic spines with high time resolution. Results from work using this new technology have confirmed the view that individual synaptic spines can act as functional chemical compartments with independent dynamics of second-messenger concentration. In particular, the ability of Ca2+ to directly mediate Hebbian coincidence detection has been confirmed.

Animals↗
PubMed2004

Optical sectioning deep inside live embryos by selective plane illumination microscopy.

Large, living biological specimens present challenges to existing optical imaging techniques because of their absorptive and scattering properties. We developed selective plane illumination microscopy (SPIM) to generate multidimensional images of samples up to a few millimeters in size. The system combines two-dimensional illumination with orthogonal camera-based detection to achieve high-resolution, optically sectioned imaging throughout the sample, with minimal photodamage and at speeds capable of capturing transient biological phenomena. We used SPIM to visualize all muscles in vivo in the transgenic Medaka line Arnie, which expresses green fluorescent protein in muscle tissue. We also demonstrate that SPIM can be applied to visualize the embryogenesis of the relatively opaque Drosophila melanogaster in vivo.

Anatomy, Cross-Sectional↗
PubMed2006

In vivo cytometry: a spectrum of possibilities.

BACKGROUND: We investigate whether optical imaging can reliably detect abnormalities in tissue, in a range of specimens (live cells in vitro; fixed, fresh ex-vivo and in vivo tissue), without the use of added contrast agents, and review our promising spectral methods for achieving quantitative, real-time, high resolution intrasurgical optical diagnostics. METHODS: We use reflectance, fluorescence, two-photon, and Mie scattering imaging, performed with instrumentation we developed or modified, to detect intrinsic tissue signatures. Emphasis is on spectral/hyperspectral imaging approaches allowing the equivalent of in vivo pathology. RESULTS: With experimental focus on unstained specimens, we demonstrate the ability to segment tissue images for cancer detection. Spectral reflectance imaging, coupled with advanced analysis, typically yields 90% specificity and sensitivity. Autofluorescence is also shown to be diagnostically useful, with lymph nodes results highlighted here. Elastic scattering hyperspectral imaging endoscopy, using a new instrument we designed and built, shows promise in bronchoscopic detection of dysplasia and early cancer in patients. CONCLUSIONS: The results demonstrate that advanced optical imaging can detect and localize cellular signatures of cancer in real-time, in vivo, without the use of contrast agents, in animals and humans. This is an important step towards tight spatio-temporal coupling between such detection and clinical intervention.

Animals↗
PubMed2005

Analyzing receptive fields, classification images and functional images: challenges with opportunities for synergy.

In neurophysiology, psychophysics, optical imaging and functional imaging studies, the investigator seeks a relationship between a high-dimensional variable, such as an image, and a categorical variable, such as the presence or absence of a spike or a behavior. The usual analysis strategy is fundamentally identical across these contexts--it amounts to calculating the average value of the high-dimensional variable for each value of the categorical variable and comparing these results by subtraction. Though intuitive and straightforward, this procedure may be inaccurate or inefficient and may overlook important details. Sophisticated approaches have been developed within these several experimental contexts, but they are rarely applied beyond the context in which they were developed. Recognition of the relationships among these contexts has the potential to accelerate improvements in analytic methods and to increase the amount of information that can be gleaned from experiments.

Action Potentials↗
PubMed2002

Noninvasive fluorescent imaging reliably estimates biomass in vivo.

Whole-body optical imaging of small animals has emerged as a powerful, user friendly, and high-throughput tool for assaying molecular and cellular processes as they occur in vivo. As with any imaging method, the utility of such technology relies on its ability to provide quantitative, biologically meaningful information about the physiologic or pathologic process of interest. Here we used an animal tumor model to evaluate the extent of correlation between noninvasively measured fluorescence and more traditional measurements of biomass (tumor volume and tumor weight). C57/BL6 mice were injected subcutaneously with murine colon adenocarcinoma cells that were engineered to express GFP. Serial measurements of fluorescence intensities were performed with a macroscopic in vivo fluorescence system. The progressive increases in intensity correlated strongly with growth in tumor volume, as determined by caliper measurements (R2 = 0.99). A more stringent correlation was found between fluorescence intensity and tumor weight (R2 = 0.97) than between volume and weight (R2 = 0.89). In a treatment experiment using tumor necrosis factor-alpha, fluorescence intensity (but not tumor volume) was able to differentiate between treated and control groups on day 1 post-treatment. These results validate the ability of noninvasive fluorescent imaging to quantify the number of viable, fluorescent cells in vivo.

Adenocarcinoma↗
PubMed2006

Preclinical characterization of amyloid imaging probes with multiphoton microscopy.

Multiphoton microscopy is an optical imaging technique that allows high resolution detection of fluorescence in thick, scattering tissues. The technique has been used for trans-cranial imaging of the brains of living transgenic mouse models of Alzheimer's disease. Direct detection of senile plaques in these mice has allowed the characterization of the natural history of individual senile plaques, the evaluation of plaque clearance during immunotherapy, and the characterization of the kinetics and biodistribution of the PET ligand, PIB. With the expanding repertoire of structural and functional fluorescent probes, and the preclinical characterization of new contrast agents for complementary imaging modalities like MRI, PET, SPECT, and NIRS, multiphoton microscopy will continue to be a powerful tool in understanding and combating Alzheimer's disease.

Alzheimer Disease↗
PubMed2004

A 3-dimensional ultrasound C-scan imaging technique for optic nerve measurements.

PURPOSE: To evaluate the use of 3-dimensional ultrasound C-scan imaging for optic nerve diameter measurements. DESIGN: Prospective observational case series. PARTICIPANTS: Thirty-eight normal eyes of 32 healthy adults. METHODS: Coronal C-scans of 38 normal optic nerves were imaged 3 mm behind the globe. MAIN OUTCOME MEASURES: Optic nerve sheath diameter (ONSD) and optic nerve diameter (OND). RESULTS: Mean ONSD was 4.8 mm (range: 3.9-5.9; SD 0.6), whereas mean optic OND was 1.9 mm (range: 1.8-2.1; SD 0.1). Mean ONSDs were 4.9 mm (male), 4.5 mm (female), 5.0 mm (subjects younger than 50 years), and 4.6 mm (subjects 50 and older). CONCLUSION: Coronal C-scans generated from 3-dimensional ultrasound can be used to measure the optic nerve diameters in adult eyes.

Adult↗
PubMed1984

Magnetic resonance imaging of the optic nerves and chiasm.

Magnetic resonance imaging (MR) of the optic nerves and chiasm was compared with computed tomography (CT) in 4 healthy volunteers, 4 patients without orbital or chiasmal abnormalities, and 4 patients with tumor (anterior clinoid meningioma in 2, optic nerve glioma in 1, and optic nerve sheath meningioma in 1). MR was found to be effective in demonstrating the optic nerves and related structures, particularly the intracanalicular portion of the nerve which is difficult to see with CT. Best results were achieved with partial saturation recovery (SR) images; inversion recovery (IR) and spin echo (SE) techniques were less successful because of decreased spatial resolution (in the case of SE) as well as difficulty in seeing the anterior clinoid processes. As axial views cannot always distinguish the ethmoid sinus tissue from the optic nerve, it may be necessary to employ both axial and coronal images.

Adult↗
PubMed2003

Texture analysis of optical coherence tomography images: feasibility for tissue classification.

Optical coherence tomography (OCT) acquires cross-sectional images of tissue by measuring back-reflected light. Images from in vivo OCT systems typically have a resolution of 10 to 15 mm, and are thus best suited for visualizing structures in the range of tens to hundreds of microns, such as tissue layers or glands. Many normal and abnormal tissues lack visible structures in this size range, so it may appear that OCT is unsuitable for identification of these tissues. However, examination of structure-poor OCT images reveals that they frequently display a characteristic texture that is due to speckle. We evaluated the application of statistical and spectral texture analysis techniques for differentiating tissue types based on the structural and speckle content in OCT images. Excellent correct classification rates were obtained when images had slight visual differences (mouse skin and fat, correct classification rates of 98.5 and 97.3%, respectively), and reasonable rates were obtained with nearly identical-appearing images (normal versus abnormal mouse lung, correct classification rates of 64.0 and 88.6%, respectively). This study shows that texture analysis of OCT images may be capable of differentiating tissue types without reliance on visible structures.

Adipose Tissue↗
PubMedDate not supplied

Office-based optical coherence tomographic imaging of human vocal cords.

Optical coherence tomography (OCT) is an evolving noninvasive imaging modality and has been used to image the larynx during surgical endoscopy. The design of an OCT sampling device capable of capturing images of the human larynx during a typical office based laryngoscopy examination is discussed. Both patient's and physician's movements were addressed. In vivo OCT imaging of the human larynx is demonstrated. Though the long focal length limits the lateral resolution of the image, the basement membrane can still be readily distinguished. Office-based OCT has the potential to guide surgical biopsies, direct therapy, and monitor disease. This is a promising imaging modality to study the larynx.

Equipment Design↗
PubMed2001

Regenerating optic fibers correct large-scale errors by random growth: evidence from in vivo imaging.

Regenerating optic fibers in goldfish make large-scale errors when they invade tectum and subsequently correct these to generate a projection with moderate retinotopic order by 1 month. The behavior of fibers underlying these extensive rearrangements is not well understood. To clarify this, we have imaged optic fibers in living adult goldfish at 2-4 weeks of regeneration. A small number of neighboring retinal ganglion cells were labeled with microinjections of DiI and imaged in the dorsal tectum with a cooled CCD camera on a fluorescence microscope for 5 to 8 hours. Nearly all fibers were simple unbranched processes and had endings that were highly dynamic showing both growth and retraction. Fibers from dorsal retina that normally innervate ventral tectum were frequently observed in dorsal tectum. These ectopic fibers oscillated more frequently between growth and retraction and retracted more often than ventral optic fibers. Like retinotopic fibers, ectopic fibers exhibited net growth but they showed no apparent directional preference toward their retinotopic position. In contrast, large errors along the anterior-posterior axis corresponding to nasal-temporal retina were rare and there was no differential behavior that distinguished these fibers.

Animals↗