Characterization of Tissue Microstructure Scatterer Distribution with Spectral Correlation

Characterization of tissue microstructure from the backscattered ultrasound signal using the spectral autocorrelation (SAC) function provides information about the scatterer distribution in biological tissue. This paper demonstrates SAC capabilities in characterizing periodicities in A-scans due to regularity in the scatterer distribution. The A-scan is modelled as a cyclostationary signal, where the statistical parameters of the signal vary in time with single or multiple periodicities. This periodicity manifests itself as spectral peaks both in the power spectral density (PSD) and in the SAC. Periodicity in the PSD will produce a well defined dominant peak in the cepstrum, which has been used to determine the scatterer spacing. The relationship between the scatterer spacing and the spacing of the spectral peaks is established using a stochastic model of the echo-formation process from biological tissue. The distribution of the scatterers within the microstructure is modelled using a Gamma function, which offers a flexible method of simulating parametric regularity in the scatterer spacing. Simulations of the tissue microstructure for lower orders of regularity indicate that the SAC components reveal information about the scatterer spacing that are not seen in the PSD and the cepstrum. The echo-formation process is tested by simulating microstructure of varying regularity and analyzing their effect on the SAC, PSD and cepstrum. Experimental validation of the simulation results are provided using in vivo scans of the breast and liver tissue that show the presence of significant spectral correlation components in the SAC.

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Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

Sensors ◽

10.3390/s20082379 ◽

2020 ◽

Vol 20 (8) ◽

pp. 2379 ◽

Cited By ~ 3

Author(s):

Guillermo Rus ◽

Inas H. Faris ◽

Jorge Torres ◽

Antonio Callejas ◽

Juan Melchor

Keyword(s):

Soft Tissues ◽

Elastic Parameters ◽

Tissue Microstructure ◽

Non Invasive ◽

Recent Developments ◽

Mechanical Biomarkers ◽

Nonlinear Elastic

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues’ mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

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High latitude ionospheric scintillations

Canadian Journal of Physics ◽

10.1139/p84-067 ◽

1984 ◽

Vol 62 (5) ◽

pp. 487-504 ◽

Cited By ~ 1

Author(s):

J. A. Fulford ◽

P. A. Forsyth

Keyword(s):

Statistical Parameter ◽

Spectral Density Function ◽

Statistical Characteristics ◽

Angle Of Arrival ◽

Statistical Parameters ◽

Application Systems ◽

Power Spectral ◽

Radio Signals ◽

Ionospheric Scintillations

The statistical characteristics of ionospheric irregularities are often described by specifying one or two of the statistical parameters of the scintillations that the irregularities produce in satellite radio signals. The most commonly used parameter for this purpose is the spectral index (slope of the power spectral density function on a log–log plot). While it is becoming increasingly clear that the characterization of either phase or amplitude scintillations by a single parameter may obscure significant characteristics of the scintillations, this simple approach has proven to be useful for the prediction of the behaviour of transionospheric propagation paths such as those used in various space application systems. This paper explores the use, in addition to the usual phase and amplitude observations, of measurements of angle-of-arrival, in order to characterize the scintillations. Since each of these observations represent a different kind of observational "filtering", the combination of one statistical parameter from each type of measurement should provide a more adequate characterization of the scintillations. It is found that the use of the widths of the autocorrelation functions for this purpose is preferred over the use of spectral indices.

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Characterization of Tissue Microstructure Scatterer Distribution with Spectral Correlation

Ultrasonic Imaging ◽

10.1006/uimg.1993.1015 ◽

1993 ◽

Vol 15 (3) ◽

pp. 238-254 ◽

Cited By ~ 24

Author(s):

T Varghese

Keyword(s):

Spectral Correlation ◽

Tissue Microstructure

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Rapid and Easy-to-Use Method for Accurate Characterization of Target Binding and Kinetics of Magnetic Particle Bioconjugates for Biosensing

Sensors ◽

10.3390/s21082802 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2802

Author(s):

Averyan V. Pushkarev ◽

Alexey V. Orlov ◽

Sergey L. Znoyko ◽

Vera A. Bragina ◽

Petr I. Nikitin

Keyword(s):

Optical Sensors ◽

Magnetic Particle ◽

Troponin I ◽

Sample Volume ◽

Label Free ◽

Spectral Correlation ◽

Faster Development ◽

Selection Of

The ever-increasing use of magnetic particle bioconjugates (MPB) in biosensors calls for methods of comprehensive characterization of their interaction with targets. Label-free optical sensors commonly used for studying inter-molecular interactions have limited potential for MPB because of their large size and multi-component non-transparent structure. We present an easy-to-use method that requires only three 20-min express measurements to determine the key parameters for selection of optimal MPB for a biosensor: kinetic and equilibrium characteristics, and a fraction of biomolecules on the MPB surface that are capable of active targeting. The method also provides a prognostic dependence of MPB targeting efficiency upon interaction duration and sample volume. These features are possible due to joining a magnetic lateral flow assay, a highly sensitive sensor for MPB detection by the magnetic particle quantification technique, and a novel mathematical model that explicitly describes the MPB-target interactions and does not comprise parameters to be fitted additionally. The method was demonstrated by experiments on MPB targeting of cardiac troponin I and staphylococcal enterotoxin B. The validation by an independent label-free technique of spectral-correlation interferometry showed good correlation between the results obtained by both methods. The presented method can be applied to other targets for faster development and selection of MPB for affinity sensors, analytical technologies, and realization of novel concepts of MPB-based biosensing in vivo.

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Development of a handheld near-infrared imager for dynamic characterization of in vivo biological tissue systems

Applied Optics ◽

10.1364/ao.46.007442 ◽

2007 ◽

Vol 46 (30) ◽

pp. 7442 ◽

Cited By ~ 24

Author(s):

Ronald X. Xu ◽

Bo Qiang ◽

Jimmy J. Mao ◽

Stephen P. Povoski

Keyword(s):

Biological Tissue ◽

Near Infrared ◽

Dynamic Characterization ◽

Infrared Imager ◽

Tissue Systems

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Functional characterization of human brown adipose tissue metabolism

Biochemical Journal ◽

10.1042/bcj20190464 ◽

2020 ◽

Vol 477 (7) ◽

pp. 1261-1286 ◽

Cited By ~ 3

Author(s):

Marie Anne Richard ◽

Hannah Pallubinsky ◽

Denis P. Blondin

Keyword(s):

Adipose Tissue ◽

Brown Adipose Tissue ◽

Functional Characterization ◽

Human Infants ◽

Positron Emission ◽

Brown Adipose ◽

Treatment Of Obesity ◽

And Function

Brown adipose tissue (BAT) has long been described according to its histological features as a multilocular, lipid-containing tissue, light brown in color, that is also responsive to the cold and found especially in hibernating mammals and human infants. Its presence in both hibernators and human infants, combined with its function as a heat-generating organ, raised many questions about its role in humans. Early characterizations of the tissue in humans focused on its progressive atrophy with age and its apparent importance for cold-exposed workers. However, the use of positron emission tomography (PET) with the glucose tracer [18F]fluorodeoxyglucose ([18F]FDG) made it possible to begin characterizing the possible function of BAT in adult humans, and whether it could play a role in the prevention or treatment of obesity and type 2 diabetes (T2D). This review focuses on the in vivo functional characterization of human BAT, the methodological approaches applied to examine these features and addresses critical gaps that remain in moving the field forward. Specifically, we describe the anatomical and biomolecular features of human BAT, the modalities and applications of non-invasive tools such as PET and magnetic resonance imaging coupled with spectroscopy (MRI/MRS) to study BAT morphology and function in vivo, and finally describe the functional characteristics of human BAT that have only been possible through the development and application of such tools.

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In vivo characterization of plaque composition in late Cardiac Allograft Vasculopathy

European Journal of Heart Failure Supplements ◽

10.1016/s1567-4215(08)60545-7 ◽

2008 ◽

Vol 7 ◽

pp. 196-196

Author(s):

T OBERNDORFER ◽

M FRICK ◽

J DOERLER ◽

C MUSSNER ◽

D HOEFER ◽

...

Keyword(s):

Cardiac Allograft Vasculopathy ◽

Cardiac Allograft ◽

Plaque Composition ◽

Allograft Vasculopathy ◽

In Vivo Characterization

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Comparison of Immunological and Functional Assays for Measurement of Soluble Fibrin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649796 ◽

1995 ◽

Vol 74 (02) ◽

pp. 673-679 ◽

Cited By ~ 21

Author(s):

C E Dempfle ◽

S A Pfitzner ◽

M Dollman ◽

K Huck ◽

G Stehle ◽

...

Keyword(s):

Venous Thrombosis ◽

Low Grade ◽

Plasma Samples ◽

Normal Range ◽

Soluble Fibrin ◽

Discriminating Power ◽

Fibrin Monomer ◽

Cerebral Ischemic

SummaryVarious assays have been developed for quantitation of soluble fibrin or fibrin monomer in clinical plasma samples, since this parameter directly reflects in vivo thrombin action on fibrinogen. Using plasma samples from healthy blood donors, patients with cerebral ischemic insult, patients with septicemia, and patients with venous thrombosis, we compared two immunologic tests using monoclonal antibodies against fibrin-specific neo-epitopes, and two functional tests based on the cofactor activity of soluble fibrin complexes in tPA-induced plasminogen activation. Test A (Enzymun®-Test FM) showed the best discriminating power among normal range and pathological samples. Test B (Fibrinostika® soluble fibrin) clearly separated normal range from pathological samples, but failed to discriminate among samples from patients with low grade coagulation activation in septicemia, and massive activation in venous thrombosis. Functional test C (Fibrin monomer test Behring) displayed good discriminating power between normal and pathological range samples, and correlated with test A (r = 0.61), whereas assay D (Coa-Set® Fibrin monomer) showed little discriminating power at values below 10 μg/ml and little correlation with other assays. Standardization of assays will require further characterization of analytes detected.

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