Bio

Bio


I am a staff scientist at Stanford University in the Department of Radiology where I research diffusion and perfusion MRI. Most of my work is a research stroke imaging study for which I oversee the day-to-day MRI operations. My responsibilities range from development of imaging and processing tools to exploring new image analysis methods to maintaining the smooth functioning of the stroke study with a multidisciplinary team of clinicians and researchers.

Education & Certifications


  • Ph.D., University of Wisconsin - Madison, Biomedical Engineering (2010)
  • M.S., University of Wisconsin - Madison, Biomedical Engineering (2007)
  • B.S., University of Iowa, Biomedical Engineering (2005)

Patents


  • Eric Peterson, Sean Fain. "United States Patent 7,885,702 Segmentation of the Airway Tree Using Hyperpolarized Noble Gases and Diffusion Weighted Magnetic Resonance Imaging"

Publications

Journal Articles


  • Simultaneous imaging of (13) C metabolism and (1) H structure: technical considerations and potential applications. NMR in biomedicine Gordon, J. W., Fain, S. B., Niles, D. J., Ludwig, K. D., Johnson, K. M., Peterson, E. T. 2015; 28 (5): 576-582

    Abstract

    Real-time imaging of (13) C metabolism in vivo has been enabled by recent advances in hyperpolarization. As a result of the inherently low natural abundance of endogenous (13) C nuclei, hyperpolarized (13) C images lack structural information that could be used to aid in motion detection and anatomical registration. Motion before or during the (13) C acquisition can therefore result in artifacts and misregistration that may obscure measures of metabolism. In this work, we demonstrate a method to simultaneously image both (1) H and (13) C nuclei using a dual-nucleus spectral-spatial radiofrequency excitation and a fully coincident readout for rapid multinuclear spectroscopic imaging. With the appropriate multinuclear hardware, and the means to simultaneously excite and receive on both channels, this technique is straightforward to implement requiring little to no increase in scan time. Phantom and in vivo experiments were performed with both Cartesian and spiral trajectories to validate and illustrate the utility of simultaneous acquisitions. Motion compensation of dynamic metabolic measurements acquired during free breathing was demonstrated using motion tracking derived from (1) H data. Simultaneous multinuclear imaging provides structural (1) H and metabolic (13) C images that are correlated both spatially and temporally, and are therefore amenable to joint (1) H and (13) C analysis and correction of structure-function images. Copyright © 2015 John Wiley & Sons, Ltd.

    View details for DOI 10.1002/nbm.3279

    View details for PubMedID 25810146

  • Real-Time Correction of Rigid Body Motion-Induced Phase Errors for Diffusion-Weighted Steady-State Free Precession Imaging MAGNETIC RESONANCE IN MEDICINE O'Halloran, R., Aksoy, M., Aboussouan, E., Peterson, E., Van, A., Bammer, R. 2015; 73 (2): 565-576

    Abstract

    Diffusion contrast in diffusion-weighted steady-state free precession magnetic resonance imaging (MRI) is generated through the constructive addition of signal from many coherence pathways. Motion-induced phase causes destructive interference which results in loss of signal magnitude and diffusion contrast. In this work, a three-dimensional (3D) navigator-based real-time correction of the rigid body motion-induced phase errors is developed for diffusion-weighted steady-state free precession MRI.The efficacy of the real-time prospective correction method in preserving phase coherence of the steady state is tested in 3D phantom experiments and 3D scans of healthy human subjects.In nearly all experiments, the signal magnitude in images obtained with proposed prospective correction was higher than the signal magnitude in images obtained with no correction. In the human subjects, the mean magnitude signal in the data was up to 30% higher with prospective motion correction than without. Prospective correction never resulted in a decrease in mean signal magnitude in either the data or in the images.The proposed prospective motion correction method is shown to preserve the phase coherence of the steady state in diffusion-weighted steady-state free precession MRI, thus mitigating signal magnitude losses that would confound the desired diffusion contrast. Magn Reson Med 73:565-576, 2015. © 2014 Wiley Periodicals, Inc.

    View details for DOI 10.1002/mrm.25159

    View details for Web of Science ID 000348139500013

    View details for PubMedID 24715414

  • Application of a whole-body pharmacokinetic model for targeted radionuclide therapy to NM404 and FLT PHYSICS IN MEDICINE AND BIOLOGY Grudzinski, J. J., Floberg, J. M., Mudd, S. R., Jeffery, J. J., Peterson, E. T., Nomura, A., Burnette, R. R., Tome, W. A., Weichert, J. P., Jeraj, R. 2012; 57 (6): 1641-1657

    Abstract

    We have previously developed a model that provides relative dosimetry estimates for targeted radionuclide therapy (TRT) agents. The whole-body and tumor pharmacokinetic (PK) parameters of this model can be noninvasively measured with molecular imaging, providing a means of comparing potential TRT agents. Parameter sensitivities and noise will affect the accuracy and precision of the estimated PK values and hence dosimetry estimates. The aim of this work is to apply a PK model for TRT to two agents with different magnitudes of clearance rates, NM404 and FLT, explore parameter sensitivity with respect to time and investigate the effect of noise on parameter precision and accuracy. Twenty-three tumor bearing mice were injected with a 'slow-clearing' agent, (124)I-NM404 (n = 10), or a 'fast-clearing' agent, (18)F-FLT (3'-deoxy-3'-fluorothymidine) (n = 13) and imaged via micro-PET/CT pseudo-dynamically or dynamically, respectively. Regions of interest were drawn within the heart and tumor to create time-concentration curves for blood pool and tumor. PK analysis was performed to estimate the mean and standard error of the central compartment efflux-to-influx ratio (k(12)/k(21)), central elimination rate constant (k(el)), and tumor influx-to-efflux ratio (k(34)/k(43)), as well as the mean and standard deviation of the dosimetry estimates. NM404 and FLT parameter estimation results were used to analyze model accuracy and parameter sensitivity. The accuracy of the experimental sampling schedule was compared to that of an optimal sampling schedule found using Cramer-Rao lower bounds theory. Accuracy was assessed using correlation coefficient, bias and standard error of the estimate normalized to the mean (SEE/mean). The PK parameter estimation of NM404 yielded a central clearance, k(el) (0.009 ± 0.003 h(-1)), normal body retention, k(12)/k(21) (0.69 ± 0.16), tumor retention, k(34)/k(43) (1.44 ± 0.46) and predicted dosimetry, D(tumor) (3.47 ± 1.24 Gy). The PK parameter estimation of FLT yielded a central elimination rate constant, k(el) (0.050 ± 0.025 min(-1)), normal body retention, k(12)/k(21) (2.21 ± 0.62) and tumor retention, k(34)/k(43) (0.65 ± 0.17), and predicted dosimetry, D(tumor) (0.61 ± 0.20 Gy). Compared to experimental sampling, optimal sampling decreases the dosimetry bias and SEE/mean for NM404; however, it increases bias and decreases SEE/mean for FLT. For both NM404 and FLT, central compartment efflux rate constant, k(12), and central compartment influx rate constant, k(21), possess mirroring sensitivities at relatively early time points. The instantaneous concentration in the blood, C(0), was most sensitive at early time points; central elimination, k(el), and tumor efflux, k(43), are most sensitive at later time points. A PK model for TRT was applied to both a slow-clearing, NM404, and a fast-clearing, FLT, agents in a xenograft murine model. NM404 possesses more favorable PK values according to the PK TRT model. The precise and accurate measurement of k(12), k(21), k(el), k(34) and k(43) will translate into improved and precise dosimetry estimations. This work will guide the future use of this PK model for assessing the relative effectiveness of potential TRT agents.

    View details for DOI 10.1088/0031-9155/57/6/1641

    View details for Web of Science ID 000301358000012

    View details for PubMedID 22398155

  • In Vivo Imaging and Spectroscopy of Dynamic Metabolism Using Simultaneous C-13 and H-1 MRI IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Smith, M. R., Peterson, E. T., Gordon, J. W., Niles, D. J., Rowland, I. J., Kurpad, K. N., Fain, S. B. 2012; 59 (1): 45-49

    Abstract

    Hyperpolarized (HP) (13)C-labeled pyruvate studies with magnetic resonance (MR) have been used to observe the kinetics of metabolism in vivo. Kinetic modeling to measure metabolic rates in vivo is currently limited because of nonspecific hyperpolarized signals mixing between vascular, extravascular, and intracellular compartments. In this study, simultaneous acquisition of both (1)H and (13)C signals after contrast agent injection is used to resolve specific compartments to improve the accuracy of the modeling. We demonstrate a novel technique to provide contrast to the intracellular compartments by sequential injection of HP [1-(13)C] pyruvate followed by gadolinium-chelate to provide T(1)-shortening to extra-cellular compartments. A kinetic model that distinguishes the intracellular space and includes the T(1)-shortening effect of the gadolinium chelate can then be used to directly measure the intracellular (13)C kinetics.

    View details for DOI 10.1109/TBME.2011.2161988

    View details for Web of Science ID 000298327100011

    View details for PubMedID 21775254

  • Measurement of lung airways in three dimensions using hyperpolarized helium-3 MRI PHYSICS IN MEDICINE AND BIOLOGY Peterson, E. T., Dai, J., Holmes, J. H., Fain, S. B. 2011; 56 (10): 3107-3122

    Abstract

    Large airway measurement is clinically important in cases of airway disease and trauma. The gold standard is computed tomography (CT), which allows for airway measurement. However, the ionizing radiation dose associated with CT is a major limitation in longitudinal studies and trauma. To avoid ionizing radiation from CT, we present a method for measuring the large airway diameter in humans using hyperpolarized helium-3 (HPHe) MRI in conjunction with a dynamic 3D radial acquisition. An algorithm is introduced which utilizes the significant airway contrast for semi-automated segmentation and skeletonization which is used to derive the airway lumen diameter. The HPHe MRI method was validated with quantitative CT in an excised and desiccated porcine lung (linear regression R(2) = 0.974 and slope = 0.966 over 32 airway segments). The airway lumen diameters were then compared in 24 human subjects (22 asthmatics and 2 normals; linear regression R(2) value of 0.799 and slope = 0.768 over 309 airway segments). The feasibility for airway path analysis to areas of ventilation defect is also demonstrated.

    View details for DOI 10.1088/0031-9155/56/10/014

    View details for Web of Science ID 000289937600015

    View details for PubMedID 21521907

  • Dynamic Nuclear Polarization System Output Volume Reduction Using Inert Fluids JOURNAL OF MAGNETIC RESONANCE IMAGING Peterson, E. T., Gordon, J. W., Erickson, M. G., Fain, S. B., Rowland, I. J. 2011; 33 (4): 1003-1008

    Abstract

    To present a method for significantly increasing the concentration of a hyperpolarized compound produced by a commercial dynamic nuclear polarization (DNP) polarizer, enabling the polarization process to be more suitable for preclinical applications.Using a HyperSense DNP polarizer, we investigated the combined use of perfluorocarbon and water to warm and dissolve the hyperpolarized material from the polarization temperature of 1.4K to produce material at temperatures suitable for injection.By replacing 75% of the water in the dissolution volume with a chemically and biologically inert liquid that is immiscible with water, the injection volume can be reduced 4-fold. Rapid separation of the water and perfluorocarbon mixture enables the aqueous layer containing polarized material to be easily and rapidly collected.The approach provides a significantly increased concentration of compound in a volume for injection that is more appropriate for small animal studies. This is demonstrated for (13) C-labeled pyruvic acid and (13) C-labeled succinate, but may be applied to the majority of nuclei and compounds hyperpolarized by the DNP method.

    View details for DOI 10.1002/jmri.22498

    View details for Web of Science ID 000288913200032

    View details for PubMedID 21448970

  • Hyperpolarized (13)Carbon MR CURRENT PHARMACEUTICAL BIOTECHNOLOGY Rowland, I. J., Peterson, E. T., Gordon, J. W., Fain, S. B. 2010; 11 (6): 709-719

    Abstract

    Hyperpolarized (HP) (13)C labeled compounds can be used as MR contrast agents to investigate metabolic pathways in vivo in almost real time. To date, a high proportion of reported studies have utilized HP 1-(13)C pyruvate to investigate intracellular metabolism in tumors and other tissues. The long T(1) relaxation time of the carboxylate carbon enables the (13)C signal of the pyruvate to be followed for nearly 2 minutes following injection. During this time, pyruvate is rapidly metabolized to generate observable metabolites such as alanine and lactate. HP (13)C labeled compounds have, for example, also been used to non-invasively probe physiological parameters such as pH, which emphasizes the expanding potential of the technique. The commercial availability of dynamic nuclear polarization (DNP) systems to generate hyperpolarized material for injection has made the technique available to researchers worldwide. As a consequence, DNP (13)C MR has become a rapidly expanding area of research. The technique, with its specific strengths and weaknesses, has incredible potential coupled with inherent limitations, and this review aims to both present background to the technique and describe some of the necessary hardware and software essential to perform hyperpolarized (13)C studies. An overview of the current and future role of HP (13)C based molecular imaging is presented.

    View details for Web of Science ID 000281435100018

    View details for PubMedID 20497107

  • Severe Asthma Research Program – Phenotyping and Quantification of Severe Asthma Imaging Decisions MRI Fain, S. B., Peterson, E. T., Sorkness, R. L., Wenzel, S., Castro, M., Busse, W. W. 2009; 13 (1): 24-27
  • Evaluation of structure-function relationships in asthma using multidetector CT and hyperpolarized He-3 MRI ACADEMIC RADIOLOGY Fain, S. B., Gonzalez-Fernandez, G., Peterson, E. T., Evans, M. D., Sorkness, R. L., Jarjour, N. N., Busse, W. W., Kuhlman, J. E. 2008; 15 (6): 753-762

    Abstract

    Although multiple detector computed tomography (MDCT) and hyperpolarized gas magnetic resonance imaging (HP MRI) have demonstrated ability to detect structural and ventilation abnormalities in asthma, few studies have sought to exploit or cross-validate the regional information provided by these techniques. The purpose of this work is to assess regional disease in asthma by evaluating the association of sites of ventilation defect on HP MRI with other regional markers of airway disease, including air trapping on MDCT and inflammatory markers on bronchoscopy.Both HP MRI using helium-3 and MDCT were acquired in the same patients. Supervised segmentation of the lung lobes on MRI and MDCT facilitated regional comparisons of ventilation abnormalities in the lung parenchyma. The percentage of spatial overlap was evaluated between regions of ventilation defect on HP MRI and hyperlucency on MDCT to determine associations between obstruction and likely regions of gas trapping. Similarly, lung lobes with high defect volume were compared to lobes with low defect volume for differences in inflammatory cell number and percentage using bronchoscopic assessment.There was significant overlap between sites of ventilation defect on HP MRI and hyperlucency on MDCT suggesting that sites of airway obstruction and air trapping are associated in asthma. The percent (r=0.68; P= .0039) and absolute (r=0.61; P= .0125) number of neutrophils on bronchoalveolar lavage for the sampled lung lobe also directly correlated with increased defect volume.These results show promise for using image guidance to assess specific regions of ventilation defect or air trapping in heterogeneous obstructive lung diseases such as asthma.

    View details for DOI 10.1016/j.acra.2007.10.019

    View details for Web of Science ID 000256266500009

    View details for PubMedID 18486011

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