The University of Texas System

Purdue Research Foundation

Eva M Sevick-Muraca

Zhigang Sun

Jeffery S Reynolds

Huabei Jiang

Yingqing Huang

Joseph Earl Pierce

Tamara L Troy

Joseph Pierce

Alan B Thompson

Steven Richter

Rajesh Shinde

Roy Ranadhir

Ganesh Balgi

Jeffery Kao

Dilip Y Paithankar

Jeffrey Kao

Ralf H Mayer

Michael Gurfinkel

Tianshu Pan

Ranadhir Roy

According to one embodiment of the present invention, a method for detecting lymph nodes in a human includes introducing a fluorescent contrast agent into a lymph node system of a body, directing near-infrared time-varying excitation light into the tissue of the body, causing the near-infrared time-varying excitation light to contact a lymph node of the lymphatic system, whereby a redshifted and time-varying emission light is generated, detecting the time-varying emission light at a surface of the body, filtering the time-varying emission light to reject excitation light re-emitted from the lymph node, and imaging the lymph node of the lymphatic system.

Method and system for detecting sentinel lymph nodes

According to one embodiment of the invention, a method for biomedical imaging includes directing time-varying excitation light at a surface area of a light scattering material, the material comprising a fluorescent target. Time-varying emission light from the fluorescent target is detected, substantially at a two-dimensional sensor surface, in response to the time-varying excitation light stimulating the fluorescent target. The time-varying emission light is filtered to reject excitation light re-emitted from the material. A three-dimensional image of the fluorescent target is generated based on the detection substantially at the sensor surface.

Method and system for near-infrared fluorescence contrast-enhanced imaging with area illumination and area detection

A system and method for non-invasive biomedical optical imaging and spectroscopy with low-level light is described. The technique includes a modulated light source coupled to tissue to introduce excitation light. Fluorescent light emitted in response to the excitation light is detected with a sensor. The AC intensity and phase of the excitation and detected fluorescent light is provided to a processor operatively coupled to the sensor. A processor employs the measured emission kinetics of excitation and fluorescent light to 'map' the spatial variation of one or more fluorescence characteristics of the tissue and generate a corresponding image of the tissue via an output device. The fluorescence characteristic may be provided by exogenous contrast agents, endogenous fluorophores, or both. A technique to select or design an exogenous fluorescent contrast agent to improve image contrast is also disclosed.

Imaging of light scattering tissues with fluorescent contrast agents

Methods are provided for measuring isotropic scattering coefficients of suspensions using multiply scattered radiation that is modulated in amplitude at selected modulation frequencies. The radiation may be light. Quantities describing diffusion of the multiply scattered radiation are preferably measured at a plurality of distances between source and receiver and a plurality of frequencies. Linear regression techniques are provided for maximizing accuracy of the scattering data at a selected wavelength of a radiation. Methods are provided for inversing an integral equation so as to determine a calculated value of scattering coefficient. Parameters are varied to minimize the difference between the calculated and measured scattering coefficients and thereby to determine volume fraction, particle size distribution and interparticle force between the particles in a suspension. By incorporating a first principles model to account for interparticle force, the measurements can be used to determine a parameter governing interparticle forces in a suspension. The suspension may be in a liquid or a gas.

Method for characterising particles in suspension from frequency domain photon migration measurements

A system () and method are disclosed for the self-calibrating, on-line determination of size distribution f(x) and volume fraction &#x3c6; of a number of particles (P) dispersed in a medium () by detecting one or more propagation characteristics of multiply scattered light from the particles (P). The multiply scattered light is re-emitted in response to exposure to a light source () configured to provide light at selected wavelengths. The determination includes calculating the isotropic scattering and absorption coefficients for the particles (P) by comparing the incident and detected light to determine a measurement corresponding to the propagation time through the scattering medium (), and iteratively estimating the size distribution f(x) and volume fraction &#x3c6; as a function of the coefficients for each of the wavelengths. An estimation approach based on an expected form of the distribution and the mass of the particles is also disclosed. Furthermore, techniques to determine a particle structure factor indicative of particle-to-particle interactions which vary with particle concentration and influence light scattering at high concentrations is disclosed.

Particle analysis system and method

A system () of the present invention includes light source instrumentation () to selectively illuminate a light scattering medium including a luminophore and detection instrumentation () to detect multiply scattered light output from the medium in response to illumination by the light source instrumentation (). A processor () is operatively coupled to the detection instrumentation () to determine a first optical characterization of the medium from a first multiply scattered light output of a first illumination light wavelength and a second optical characterization of the medium from a second multiply scattered light output of a second illumination light wavelength different than the first illumination light wavelength. The processor () is operable to calculate lifetime of the luminophore from the first optical characterization, the second optical characterization, and a multiply scattered emission of the luminophore from the medium in response to excitation.

Characterization of luminescence in a scattering medium

Method for characterizing particles in suspension from frequency domain photon migration measurements

Characterizing a powder bed includes generating measurements by repeating the following. A location of the powder bed is illuminated with light having a time varying intensity with a resolution of less than one hundred nanoseconds. The particles scatter the light to alter the time varying intensity. The light propagates through a portion of the particles that defines a sampled volume. The light received from the powder bed is detected. The altered time-varying intensity of the light is measured to generate a time-dependent signal having a time-dependence that is less than or equal to a time-of-flight of a photon of the propagating light. An optical property is determined from the time-dependent signal, and a characteristic is determined from the optical property. The sampled volume is determined, and variance of the measurements is calculated. Uniformity of the powder bed is determined in accordance with the variance and the sampled volume.

Characterizing powders using frequency-domain photon migration

A system and method non-invasive biomedical optical imaging and spectroscopy with low-level light is described. The technique consists of a modulated light source (120) coupled to tissue (100) of a patient to introduce excitation light. Fluorescent light emitted in response to the excitation light is detected with sensor (148). The AC intensity and phase of the excitation and detected fluorescent light is provided to a processor (160) operatively coupled to sensor (148). Processor (160) employs the measured re-emission kinetics of excitation and fluorescent light to 'map' the spatial variation of one or more fluorescence characteristics of the tissue (100). The fluorescence characteristic may be provided by exogenous contract agents, endogenous fluorophores, or both. The variation is determined by solving frequency domain diffusion equations at a number of designated points in the tissue as part of a recursive estimation algorithm. Processor (160) generates an imaging signal in accordance with the spatial variation of the fluorescence characteristic for provision to an output device (164). The output device (164) displays an image corresponding spatial variation of the fluorescence characteristic which corresponds to tissue (100) to aid in the detection and diagnosis of disease.

Fluorescence imaging system and method

A system and method are disclosed for the self-calibrating, on-line determination of size distribution and volume fraction of a number of particles dispersed in a medium by detecting multiply scattered light from the particles. The multiply scattered light is re-emitted in response to exposure to a light source configured to provide light of time varying intensity at selected wavelengths. The determination includes calculating the isotropic scattering coefficient for the particles at each of a number of wavelengths from the multiply scattered light as a function of an intensity modulation phase shift, and iteratively estimating the size distribution and volume fraction as a function of the isotropic scattering coefficient for each of the wavelengths. An estimation approach based on an expected form of the distribution and the mass of the particles is also disclosed.

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College Station, TX, United States of America

Eva M Sevick-Muraca