Prof. Keith M. Stantz Profile

Prof. Keith M. Stantz

Assistant Professor at Purdue Univ School of Health Sciences

SPIE Involvement:

Author

Publications (23)

Proceedings Article | 2 March 2015 Paper

Paper

An empirical approach to estimate near-infra-red photon propagation and optically induced drug release in brain tissues

Akshay Prabhu Verleker, Qianqian Fang, Mi-Ran Choi, Susan Clare, Keith Stantz

Proceedings Volume 9308, 93080T (2015) https://doi.org/10.1117/12.2079991

KEYWORDS: Monte Carlo methods, Photon transport, Tissues, Brain, Tissue optics, Optical simulations, Geometrical optics, Scattering, Absorption, Computer simulations

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Proceedings Article | 26 February 2010 Paper

Paper

Imaging hypoxia using 3D photoacoustic spectroscopy

Keith Stantz

Proceedings Volume 7564, 756419 (2010) https://doi.org/10.1117/12.842143

KEYWORDS: Oxygen, Tumors, Hypoxia, Photoacoustic spectroscopy, Hemodynamics, Cancer, Blood, In vivo imaging, Tissues, Tumor growth modeling

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Proceedings Article | 26 February 2010 Paper

Paper

Molecular imaging of neutropilin-1 receptor using photoacoustic spectroscopy in breast tumors

Keith Stantz, Minsong Cao, Bo Liu, Kathy Miller, Lili Guo

Proceedings Volume 7564, 75641O (2010) https://doi.org/10.1117/12.842271

KEYWORDS: Tumors, Photoacoustic spectroscopy, Near infrared, In vivo imaging, Receptors, Luminescence, Calibration, Breast, Absorption, Molecular imaging

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Proceedings Article | 24 February 2010 Paper

Paper

Evaluation of Her2 status using photoacoustic spectroscopic CT techniques

Michael Shaffer, Robert Kruger, Daniel Reinecke, Helen Chin-Sinex, Marc Mendonca, Keith Stantz

Proceedings Volume 7564, 756435 (2010) https://doi.org/10.1117/12.842639

KEYWORDS: Tumors, Spectroscopy, Photoacoustic spectroscopy, Oxygen, Luminescence, Near infrared, In vivo imaging, Scanners, Data acquisition, Near infrared spectroscopy

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Proceedings Article | 24 February 2010 Paper

Paper

Ex vivo hemoglobin status study using photoacoustic computed tomography small animal scanner

Bo Liu, Robert Kruger, Daniel Reinecke, Keith Stantz

Proceedings Volume 7564, 75643A (2010) https://doi.org/10.1117/12.842836

KEYWORDS: Blood, Oxygen, Scanners, Photon transport, Error analysis, Absorption, Monte Carlo methods, Molecules, Acoustics, Imaging systems

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Proceedings Article | 24 February 2010 Paper

Paper

Monitor hemoglobin concentration and oxygen saturation in living mouse tail using photoacoustic CT scanner

Bo Liu, Robert Kruger, Daniel Reinecke, Keith Stantz

Proceedings Volume 7564, 756439 (2010) https://doi.org/10.1117/12.842827

KEYWORDS: Oxygen, Scanners, Spectroscopy, Arteries, Photoacoustic spectroscopy, Blood, Acoustics, Veins, Bone, Imaging spectroscopy

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Proceedings Article | 24 February 2010 Paper

Paper

Effects of radiation on tumor hemodynamics and NF-kappaB in breast tumors

Keith Stantz, Ning Cao, Bo Liu, Minsong Cao, Helen Chin-Sinex, Marc Mendonca, Jian Jian Li

Proceedings Volume 7564, 75641J (2010) https://doi.org/10.1117/12.842238

KEYWORDS: Tumors, Oxygen, Photoacoustic spectroscopy, Hemodynamics, Radiation effects, In vivo imaging, Imaging spectroscopy, Breast, Breast cancer, Computed tomography

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Proceedings Article | 24 February 2010 Paper

Paper

Photon propagation correction in 3D photoacoustic image reconstruction using Monte Carlo simulation

Yaw Jye Cheong, Keith Stantz

Proceedings Volume 7564, 75640G (2010) https://doi.org/10.1117/12.842196

KEYWORDS: Monte Carlo methods, Absorption, Error analysis, Optical spheres, Scattering, Algorithm development, Reconstruction algorithms, Tumors, Photon transport, Photoacoustic spectroscopy

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Proceedings Article | 25 February 2009 Paper

Paper

HYPR-spectral photoacoustic CT for preclinical imaging

Robert Kruger, Daniel Reinecke, Gabe Kruger, Michael Thornton, Paul Picot, Timothy Morgan, Keith Stantz, Charles Mistretta

Proceedings Volume 7177, 71770F (2009) https://doi.org/10.1117/12.810175

KEYWORDS: Spatial resolution, Scanners, Photoacoustic spectroscopy, Signal to noise ratio, Computed tomography, Preclinical imaging, 3D acquisition, Composites, Sensors, 3D image processing

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Proceedings Article | 13 February 2007 Paper

Paper

Using Monte Carlo simulations to understand the influence of photon propagation on photoacoustic spectroscopic imaging

Keith Stantz, Bo Liu, Robert Kruger

Proceedings Volume 6437, 64370Z (2007) https://doi.org/10.1117/12.701395

KEYWORDS: Monte Carlo methods, Tumors, Blood, Photoacoustic spectroscopy, Absorption, Near infrared, Tissue optics, Photon transport, Acoustics, Signal attenuation

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Purpose: The purpose of this study is to evaluate the influence of photon propagation on the NIR spectral features associated with photoacoustic imaging. Introduction: Photoacoustic CT spectroscopy (PCT-S) has the potential to identify molecular properties of tumors while overcoming the limited depth resolution associated with optical imaging modalities (e.g., OCT and DOT). Photoacoustics is based on the fact that biological tissue generates high-frequency acoustic signals due to volume of expansion when irradiated by pulsed light. The amplitude of the acoustic signal is proportional to the optical absorption properties of tissue, which varies with wavelength depending on the molecular makeup of the tissue. To obtain quantifiable information necessitate modeling and correcting for photon and acoustic propagation in tumors. Material and Methods: A Monte Carlo (MC) algorithm based on MCML (Monte Carlo for Multi-Layered edia) has been developed to simulate photon propagation within objects comprised of a series of complex 3D surfaces (Mcml3D). This code has been used to simulate and correct for the optical attenuation of photons in blood, and for subcutaneous tumors with homogenous and radially heterogeneous vascular distributions. Results: The NIR spectra for oxygenated and deoxygenated blood as determined from Monte Carlo simulated photoacoustic data matched measured data, and improving oxygen saturation calculations. Subcutaneous tumors with a homogeneous and radially heterogeneous distribution of blood revealed large variations in photon absorption as a function of the scanner projection angle. For select voxels near the periphery of the tumor, this angular profile between the two different tumors appeared similar. Conclusions: A Monte Carlo code has been successfully developed and used to correct for photon propagation effects in blood phantoms and restoring the integrity of the NIR spectra associated with oxygenated and deoxygenated blood. This code can be used to simulate the influence of intra-tumor heterogeneity on the molecular identification via NIR spectroscopy.

Proceedings Article | 13 February 2007 Paper

Paper

Phantom and in-vivo measurements of hemoglobin concentration and oxygen saturation using PCT-S small animal scanner

Bo Liu, Daniel Reinecke, Robert Kruger, Keith Stantz

Proceedings Volume 6437, 64371X (2007) https://doi.org/10.1117/12.701376

KEYWORDS: Blood, Oxygen, Scanners, Absorption, Tumors, In vivo imaging, Veins, Arteries, Hypoxia, Calibration

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Proceedings Article | 20 March 2006 Paper

Paper

Evaluating dynamic contrast-enhanced and photoacoustic CT to assess intra-tumor heterogeneity in xenograft mouse models

Keith Stantz, Bo Liu, Minsong Cao, Dan Reinecke, Mario Dzemidzic, Yun Liang, Robert Kruger

Proceedings Volume 6143, 61431F (2006) https://doi.org/10.1117/12.654056

KEYWORDS: Tumors, Oxygen, Blood, Photoacoustic spectroscopy, Breast, In vivo imaging, Vascular physiology, Calibration, Error analysis, Plasma

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Proceedings Article | 13 March 2006 Paper

Paper

Myocardial physiology measurements using contrast enhanced dynamic computed tomography: simulation of beam hardening effect

Minsong Cao, Keith Stantz, Yun Liang

Proceedings Volume 6143, 61432N (2006) https://doi.org/10.1117/12.654206

KEYWORDS: Physiology, Computer simulations, Heart, Iodine, X-ray computed tomography, X-rays, Error analysis, Optical simulations, Scanners, Computed tomography

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Proceedings Article | 6 March 2006 Paper

Paper

Assessment of photoacoustic computed tomography to classify tissue in a polycystic-kidney disease mouse model

Bo Liu, Vincent Gattone, Robert Kruger, Keith Stantz

Proceedings Volume 6086, 608607 (2006) https://doi.org/10.1117/12.646180

KEYWORDS: Kidney, Tissues, Mouse models, Tissue optics, Image segmentation, Photons, Photoacoustic tomography, Photography, Computed tomography, Absorption

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Proceedings Article | 6 March 2006 Paper

Paper

Photoacoustic spectroscopic imaging of intra-tumor heterogeneity and molecular identification

Keith Stantz, Bo Liu, Minsong Cao, Daniel Reinecke, Kathy Miller, Robert Kruger

Proceedings Volume 6086, 608605 (2006) https://doi.org/10.1117/12.645106

KEYWORDS: Tumors, Blood, Photoacoustic spectroscopy, In vivo imaging, Spectroscopy, Error analysis, Oxygen, Liver, Tissue optics, Bladder

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Purpose. To evaluate photoacoustic spectroscopy as a potential imaging modality capable of measuring intra-tumor heterogeneity and spectral features associated with hemoglobin and the molecular probe indocyanine green (ICG). Material and Methods. Immune deficient mice were injected with wildtype and VEGF enhanced MCF-7 breast cancer cells or SKOV3x ovarian cancer cells, which were allowed to grow to a size of 6-12 mm in diameter. Two mice were imaged alive and after euthanasia for (oxy/deoxy)-hemoglobin content. A 0.4 mL volume of 1 μg/mL concentration of ICG was injected into the tail veins of two mice prior to imaging using the photoacoustic computed tomography (PCT) spectrometer (Optosonics, Inc., Indianapolis, IN 46202) scanner. Mouse images were acquired for wavelengths spanning 700-920 nm, after which the major organs were excised, and similarly imaged. A histological study was performed by sectioning the organ and optically imaging the fluorescence distribution. Results. Calibration of PCT-spectroscopy with different samples of oxygenated blood reproduced a hemoglobin dissociation curve consistent with empirical formula with an average error of 5.6%. In vivo PCT determination of SaO₂ levels within the tumor vascular was measurably tracked, and spatially correlated to the periphery of the tumor. Statistical and systematic errors associated with hypoxia were estimated to be 10 and 13%, respectively. Measured ICG concentrations determined by contrast-differential PCT images in excised organs (tumor, liver) were approximately 0.8 μg/mL, consistent with fluorescent histological results. Also, the difference in the ratio of ICG concentration in the gall bladder-to-vasculature between the mice was consistent with excretion times between the two mice. Conclusion. PCT spectroscopic imaging has shown to be a noninvasive modality capable of imaging intra-tumor heterogeneity of (oxy/deoxy)-hemoglobin and ICG in vivo, with an estimated error in SaO₂ at 17% and in ICG at 0.8 μg/mL in excised tissue. Ongoing development of spectroscopic analysis techniques, probe development, and calibration techniques are being developed to improve sensitivity to both exogenous molecular probes and (oxy/deoxy)-hemoglobin fraction.

Proceedings Article | 14 April 2005 Paper

Paper

Assessment of multislice CT to quantify pulmonary emphysema function and physiology in a rat model

Minsong Cao, Keith Stantz, Yun Liang, Ganapathy Krishnamurthi, Robert Presson

Proceedings Volume 5746, (2005) https://doi.org/10.1117/12.595775

KEYWORDS: Lung, Emphysema, Computed tomography, Capillaries, Signal attenuation, Tissues, Animal model studies, Physiology, Image segmentation, Blood

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Proceedings Article | 30 April 2004 Paper

Paper

Kinematic modeling and its implication in longitudinal chemotherapy study of tumor physiology: ovarian xenograft mouse model and contrast-enhanced dynamic CT (Honorable Mention Poster Award)

Keith Stantz, Yun Liang, Gary Hutchins

Proceedings Volume 5369, (2004) https://doi.org/10.1117/12.536212

KEYWORDS: Tumors, Error analysis, Picosecond phenomena, Physiology, Computed tomography, Mouse models, Plasma, Scanners, Temporal resolution, Tissues

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The purpose of this study is to demonstrate that dynamic CT provides the necessary sensitivity to quantify tumor physiology and differences in chemotherapeutic response. A compartmental mouse model utilizing measured contrast-enhanced dynamic CT scans is used to simulate systematic and statistical errors associated with tumor physiology: perfusion, permeability (PS), fractional plasma volume (f_p), and fractional interstitial volume. The solute utilized is a small molecular weight radio-opaque contrast agent (isovue). For such an intravascular-interstitial medium, the kinematics simplifies to a two compartmental diffusive dominated set of coupled differential equations. Each combination of physiological parameters is repeatedly simulated fifteen times from which statistical errors calculated. The fractional change relative to the true value (systematic error) and standard deviation (statistical error) are plotted as a function of PS, f_p, scanner temporal resolution and noise, and contrast media injection rates. By extrapolating from experimental data found in literature, a relative change in PS and f_p of approximately 40% is required. Thus, the longitudinal response of two chemotherapeutic drugs under investigation - proteasome and IMPDH inhibitors - are hypothesized to induce different physiological responses. The first set of simulations varies PS from 0.05 to 0.40 mL/min/mL and f_p from 0.01 to 0.07 mL/mL while holding all other physiological parameters constant. Errors in PS remain below 3% while statistical errors for f_p increase significantly as the volume decreases toward 1-2%: errors remain less than 6% for f_p>0.03 while increasing to above 15% for f_p<0.02. The second set of simulations are performed quantifying the relationship between scanner temporal resolution and contrast media injection rate for various tumor permeabilities. For the majority of cases, the errors remain below 5%. As PS approaches perfusion, a total error less than 6% can be maintained for a temporal resolution less than or equal to 3 seconds, and an error less than 9% up to 5-7 seconds. As the injection rate decreases from 2 mL/min down to 0.25 mL/min, inadequate sampling of the contrast dynamics necessary to decouple the physiological parameters is lost increasing both systematic and statistical errors from 10% when sampling at 5 seconds in excess of 20-25% at a 9 second sampling rate. In each case, dynamic CT provides the necessary sensitivity to distinguish between the differing therapeutic reponses of proteasome and IMPDH inhibitors.

Proceedings Article | 30 April 2004 Paper

Paper

Reproducibility of physiologic parameters obtained using functional computed tomography in mice

Ganapathy Krishnamurthi, Keith Stantz, Rosemary Steinmetz, Gary Hutchins, Yun Liang

Proceedings Volume 5369, (2004) https://doi.org/10.1117/12.536255

KEYWORDS: Tissues, Kidney, Heart, Capillaries, Tumors, Computed tomography, Physiology, Picosecond phenomena, X-ray computed tomography, Iodine

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Proceedings Article | 2 May 2003 Paper

Paper

In-vivo regional myocardial perfusion measurements in a porcine model by ECG-gated multislice computed tomography

Keith Stantz, Yun Liang, Cristopher Meyer, Shawn Teague, Michael Stecker, Gary Hutchins, Gordon McLennan, Scott Persohn

Proceedings Volume 5031, (2003) https://doi.org/10.1117/12.480431

KEYWORDS: Computed tomography, Heart, Positron emission tomography, Arteries, Tissues, Blood, Data modeling, Motion models, Scanners, Blood circulation

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Purpose: To evaluate whether functional multi-slice computed tomography (MSCT) can identify regional areas of normally perfused and ischemic myocardium in a porcine model. Material and Methods: Three out bred pigs, two of which had ameroids surgically implanted to constrict flow within the LAD and LCx coronary arteries, were injected with 25 mL of iopromide (Isovue) at a rate of 5 mL/second via the femoral or jugular vein. Sixty axial scans along the short axis of the heart was acquired on a 16-slice CT scanner (Philips MX8000-IDT) triggered at end-diastole of the cardiac cycle and acquiring an image within 270 msec. A second series of scans were taken after an intravenous injection of a vasodilator, 150 μg/kg/min of adenosine. ROIs were drawn around the myocardial tissue and the resulting time-density curves were used to extract perfusion values. Results: Determination of the myocardial perfusion and fractional blood volume implementing three different perfusion models. A 5-point averaging or 'smoothing' algorithm was employed to effectively filter the data due to its noisy nature. The (preliminary) average perfusion and fractional blood volume values over selected axial slices for the pig without an artificially induced stenosis were measured to be 84 ± 22 mL/min/100g-tissue and 0.17 ± 0.04 mL/g-tissue, the former is consistent with PET scan and EBCT results. The pig with a stenosis in the left LAD coronary artery showed a reduced global perfusion value -- 45 mL/min/100g-tissue. Correlations in regional perfusion values relative to the stenosis were weak. During the infusion of adenosine, averaged perfusion values for the three subjects increased by 46 (±45) percent, comparable to increases measured with PET. Conclusion: Quantifying global perfusion values using MDCT appear encouraging. Future work will focus resolving the systematic effects from noise due to signal fluctuation from the porcine tachyardia (80-93 BPM) and provide a more robust measurement of regional myocardial perfusion throughout the heart.

Proceedings Article | 2 May 2003 Paper

Paper

Development of contrast-enhanced rodent imaging using functional CT

Yun Liang, Keith Stantz, Ganapathy Krishnamurthi, Rosemary Steinmetz, Gary Hutchins

Proceedings Volume 5031, (2003) https://doi.org/10.1117/12.480690

KEYWORDS: Tissues, Tumors, Kidney, Physiology, Imaging systems, Scanners, X-ray computed tomography, Computed tomography, Blood, Capillaries

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Proceedings Article | 3 May 2002 Paper

Paper

Thermoacoustic CT of the breast

Robert Kruger, Keith Stantz, William Kiser

Proceedings Volume 4682, (2002) https://doi.org/10.1117/12.465596

KEYWORDS: Scanners, Breast, Transducers, Waveguides, Image quality, Optical spheres, Data acquisition, Computed tomography, 3D image processing, Ultrasonography

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Proceedings Article | 30 July 1999 Paper

Paper

Adaptive remote sensing techniques implementing swarms of mobile agents

Stewart Cameron, Guillermo Loubriel, Rush Robinett, Keith Stantz, Michael Trahan, John Wagner

Proceedings Volume 3713, (1999) https://doi.org/10.1117/12.357131

KEYWORDS: Sensors, Neural networks, Remote sensing, Antennas, Optical communications, Robotics, Radar, Superposition, Intelligent sensors, Modulators

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Proceedings Article | 22 July 1999 Paper

Paper

Dynamic behavior of multirobot systems using lattice gas automata

Keith Stantz, Stewart Cameron, Rush Robinett, Michael Trahan, John Wagner

Proceedings Volume 3693, (1999) https://doi.org/10.1117/12.354461

KEYWORDS: Robots, Sensors, Robotics, Systems modeling, Motion models, Particles, Kinematics, Artificial intelligence, Genetic algorithms, Neural networks

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Recent attention has been given to the deployment of an adaptable sensor array realized by multi-robotic systems (or swarms). Our group has been studying the collective, autonomous behavior of these such systems and their applications in the area of remote-sensing and emerging threats. To accomplish such tasks, an interdisciplinary research effort at Sandia National Laboratories are conducting tests in the fields of sensor technology, robotics, and multi- agents architectures. Our goal is to coordinate a constellation of point sensors using unmanned robotic vehicles (e.g., RATLERs, Robotic All-Terrain Lunar Exploration Rover- class vehicles) that optimizes spatial coverage and multivariate signal analysis. An overall design methodology evolves complex collective behaviors realized through local interaction (kinetic) physics and artificial intelligence. Learning objectives incorporate real-time operational responses to environmental changes. This paper focuses on our recent work understanding the dynamics of many-body systems according to the physics-based hydrodynamic model of lattice gas automata. Three design features are investigated. One, for single-speed robots, a hexagonal nearest-neighbor interaction topology is necessary to preserve standard hydrodynamic flow. Two, adaptability, defined by the swarm's rate of deformation, can be controlled through the hydrodynamic viscosity term, which, in turn, is defined by the local robotic interaction rules. Three, due to the inherent nonlinearity of the dynamical equations describing large ensembles, stability criteria ensuring convergence to equilibrium states is developed by scaling information flow rates relative to a swarm's hydrodynamic flow rate. An initial test case simulates a swarm of twenty-five robots maneuvering past an obstacle while following a moving target. A genetic algorithm optimizes applied nearest-neighbor forces in each of five spatial regions distributed over the simulation domain. Armed with this knowledge, the swarm adapts by changing state in order to avoid the obstacle. Simulation results are qualitatively similar to a lattice gas.

Showing 5 of 23 publications

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