Stephen A Boppart

University of Illinois, Urbana-Champaign, Urbana, Illinois, United States

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Publications (376)897.39 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic particles are versatile imaging agents that have found wide spread applicability in diagnostic, therapeutic, and rheology applications. In this study, we demonstrate that mechanical waves generated by a localized inclusion of magnetic nanoparticles can be used for assessment of the tissue viscoelastic properties using magnetomotive optical coherence elastography. We show these capabilities in tissue mimicking elastic and viscoelastic phantoms and in biological tissues by measuring the shear wave speed under magnetomotive excitation. Furthermore, we demonstrate the extraction of the complex shear modulus by measuring the shear wave speed at different frequencies and fitting to a Kelvin-Voigt model.
    Biomedical Optics Express 07/2014; 5(7). · 3.18 Impact Factor
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    ABSTRACT: There is an inherent trade-off between transverse resolution and depth of field (DOF) in optical coherence tomography (OCT) which becomes a limiting factor for certain applications. Multifocal OCT and interferometric synthetic aperture microscopy (ISAM) each provide a distinct solution to the trade-off through modification to the experiment or via post-processing, respectively. In this paper, we have solved the inverse problem of multifocal OCT and present a general algorithm for combining multiple ISAM datasets. Multifocal ISAM (MISAM) uses a regularized combination of the resampled datasets to bring advantages of both multifocal OCT and ISAM to achieve optimal transverse resolution, extended effective DOF and improved signal-to-noise ratio. We present theory, simulation and experimental results.
    Optics express. 06/2014; 22(13):16606-16618.
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    ABSTRACT: We demonstrate the broadband electrical tunability of ultrafast fiber laser output across the visible range, from the deep blue to the infrared.
    CLEO: Applications and Technology; 06/2014
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    ABSTRACT: We demonstrate the combination of interferometric synthetic aperture microscopy (ISAM), computational adaptive optics (CAO) and coherence tomography microscopy (OCM) provides a high-speed volumetric cellular imaging.
    Biomedical Optics; 04/2014
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    ABSTRACT: In this study, we developed an intravascular magnetomotive optical coherence tomography (IV-MM-OCT) system to detect early-stage atherosclerotic fatty streaks/plaques.
    Biomedical Optics; 04/2014
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    ABSTRACT: Primary care physicians must conduct a staggering number of comprehensive physical exams and medical record reviews, resulting in demanding daily schedules. Few commercial technologies have been marketed towards the primary care market, which has stifled improvements in disease screening and detection, work flow, and records management, taking time away from interactions with patients. In efforts to improve the quality of care in primary care medicine, we integrated our handheld primary care optical imaging system with Google Glass©, a commercial heads-up display (HUD). The integration of a HUD allows the physician to focus on the patient during the medical history review and during the patient exam, resulting in potential improvements to the quality of care and efficient access to real-time data for display and analysis.
    01/2014;
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    ABSTRACT: Breast-conserving surgery is a frequent option for women with stage I and II breast cancer, and with radiation treatment, can be as effective as a mastectomy. However, adequate margin detection remains a challenge, and too often additional surgeries are required. Optical coherence tomography (OCT) provides a potential method for real-time, high-resolution imaging of breast tissue during surgery. Intra-operative OCT imaging of excised breast tissues has been previously demonstrated by several groups. In this study, a novel handheld surgical probe-based OCT system is introduced, which was used by the surgeon to image in vivo, within the tumor cavity, and immediately following tumor removal in order to detect the presence of any remaining cancer. Following resection, study investigators imaged the excised tissue with the same probe for comparison. We present OCT images obtained from over 15 patients during lumpectomy and mastectomy surgeries. Images were compared to post-operative histopathology for diagnosis. OCT images with micron scale resolution show areas of heterogeneity and disorganized features indicative of malignancy, compared to more uniform regions of normal tissue. Video-rate acquisition shows the inside of the tumor cavity as the surgeon sweeps the probe along the walls of the surgical cavity. This demonstrates the potential of OCT for real-time assessment of surgical tumor margins and for reducing the unacceptably high re-operation rate for breast cancer patients.
    01/2014;
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    ABSTRACT: We present a real-time multimodal near-infrared imaging technology that tracks externally-induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM). MPM is utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells.
    IEEE Journal of Selected Topics in Quantum Electronics 01/2014; 20(2):1-7. · 4.08 Impact Factor
  • Haohua Tu, Youbo Zhao, Yuan Liu, Stephen A. Boppart
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    ABSTRACT: An intriguing phenomenon of third-harmonic generation under fiber continuum generation is the emission of an anharmonic signal. One popular interpretation of this effect has developed into a general theory of fiber third-harmonic generation. Here we produce "static" third-harmonic lines dictated fully by fiber properties independent of pump parameters, in contrast to the signals of all known phase-matched nonlinear optical processes that vary dynamically with these parameters. We argue that the anharmonic signal is an illusion of the continuum generation, that it is in fact harmonic, and that this theory should be reevaluated.
    12/2013; 89(1).
  • Journal of Biomedical Optics 12/2013; 18(12):121501. · 2.88 Impact Factor
  • Vasilica Crecea, Adeel Ahmad, Stephen A Boppart
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    ABSTRACT: Optical coherence elastography (OCE) is an established paradigm for measuring biomechanical properties of tissues and cells noninvasively, in real time, and with high resolution. We present a different development of a spectral domain OCE technique that enables simultaneous measurements of multiple biomechanical parameters of biological tissues. Our approach extends the capabilities of magnetomotive OCE (MM-OCE), which utilizes iron oxide magnetic nanoparticles (MNPs) distributed and embedded in the specimens as transducers for inducing motion. Step-wise application of an external magnetic field results in displacements in the tissue specimens that are deduced from sensitive phase measurements made with the MM-OCE system. We analyzed freshly excised rabbit lung and muscle tissues. We observe that while they present some similarities, rabbit lung and muscle tissue displacements display characteristic differentiating features. Both tissue types undergo a fast initial displacement followed by a rapidly damped oscillation and the onset of creep. However, the damping is faster in muscle compared to lung tissue, while the creep is steeper in muscle. This approach has the potential to become a novel way of performing real-time measurements of biomechanical properties of tissues and to enable the development of different diagnostic and monitoring tools in biology and medicine.
    Journal of Biomedical Optics 12/2013; 18(12):121504. · 2.88 Impact Factor
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    ABSTRACT: A major challenge for translating cell-based therapies is understanding the dynamics of cells and cell populations in complex in vivo environments. Intravital microscopy has shown great promise for directly visualizing cell behavior in vivo. However, current methods are limited to relatively short imaging times (hours), by ways to track cell and cell population dynamics over extended time-lapse periods (days to weeks to months), and by relatively few imaging contrast mechanisms that persist over extended investigations. We present technology to visualize and quantify complex, multifaceted dynamic changes in natural deformable skin over long time periods using novel multimodal imaging and a non-rigid image registration method. These are demonstrated in green fluorescent protein (GFP) bone marrow (BM) transplanted mice to study dynamic skin regeneration. This technology provides a novel perspective for studying dynamic biological processes and will enable future studies of stem, immune, and tumor cell biology in vivo.
    TECHNOLOGY. 11/2013; 01(01).
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    ABSTRACT: We predict and realize the targeted wavelength conversion from the 1550-nm band of a fs Er:fiber laser to an isolated band inside 370-850 nm, corresponding to a blue-shift of 700-1180 nm. The conversion utilizes resonant dispersive wave generation in widely available optical fibers with good efficiency (~7%). The converted band has a large pulse energy (~1 nJ), high spectral brightness (~1 mW/nm), and broad Gaussian-like spectrum compressible to clean transform-limited ~17 fs pulses. The corresponding coherent fiber sources open up portable applications of optical parametric oscillators and dual-output synchronized ultrafast lasers.
    Optics Express 10/2013; 21(20):23188-23196. · 3.55 Impact Factor
  • Haohua Tu, Stephen A Boppart
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    ABSTRACT: Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber-based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well-known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low-cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point-of-care coherent optical biomedical imaging.
    Laser & Photonics Review 09/2013; 7(5). · 7.98 Impact Factor
  • Haohua Tu, Stephen Boppart
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    ABSTRACT: We have developed fiber-based Cherenkov radiation sources emitting broadband pulses with nJ-level pulse energy, 50-mW-level average power, and isolated Gaussian-like spectra of ~40-nm FWHM bandwidth in the visible free of non-specific supercontinuum emission.
    Workshop on Specialty Optical Fibers and their Applications; 08/2013
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    ABSTRACT: We investigated the early-stage fatty streaks/plaques detection using magnetomotive optical coherence tomography (MM-OCT) in conjunction with αvβ3 integrin-targeted magnetic microspheres (MSs). The targeting of functionalized MSs was investigated by perfusing ex vivo aortas from an atherosclerotic rabbit model in a custom-designed flow chamber at physiologically relevant pulsatile flow rates and pressures. Aortas were extracted and placed in a flow chamber. Magnetic MS contrast agents were perfused through the aortas and MM-OCT, fluorescence confocal, and bright field microscopy were performed on the ex vivo aorta specimens for localizing the MSs. The results showed a statistically significant and stronger MM-OCT signal (3.30 ± 1.73 dB) from the aorta segment perfused with targeted MSs, compared with the nontargeted MSs (1.18 ± 0.94 dB) and control (0.78 ± 0.41 dB) aortas. In addition, there was a good co-registration of MM-OCT signals with confocal microscopy. Early-stage fatty streaks/plaques have been successfully detected using MM-OCT in conjunction with αvβ3 integrin-targeted magnetic MSs.
    Molecular imaging and biology: MIB: the official publication of the Academy of Molecular Imaging 08/2013; · 2.47 Impact Factor
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    ABSTRACT: In this paper, we report on a novel quantitative elastography technique that combines optical coherence tomography (OCT) with acoustic radiation force (ARF) excitation to estimate the complex modulus. Sinusoidally modulated ARF excitations between 200 - 4000 Hz generate a surface wave at the tissue surface that can be related to bulk viscoelastic (VE) properties in a manner that is both precise and quantitative. This method is very well suited to studying media at high spatial resolution and over a very broad range of force frequencies. Mechanical characterization was calibrated using hydropolymers before studying liver samples. Fresh porcine liver samples were measured over time with and without formalin fixation. These data were used to evaluate the utility of the Kelvin-Voigt rheological model commonly used to fit dispersion data when estimating modulus values. We also investigated use of square-wave force excitation to measure the step response of tissues.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 07/2013; 2013:117-120.
  • Source
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    ABSTRACT: High-resolution real-time tomography of scattering tissues is important for many areas of medicine and biology(1-6). However, the compromise between transverse resolution and depth-of-field in addition to low sensitivity deep in tissue continue to impede progress towards cellular-level volumetric tomography. Computed imaging has the potential to solve these long-standing limitations. Interferometric synthetic aperture microscopy (ISAM)(7-9) is a computed imaging technique enabling high-resolution volumetric tomography with spatially invariant resolution. However, its potential for clinical diagnostics remains largely untapped since full volume reconstructions required lengthy postprocessing, and the phase-stability requirements have been difficult to satisfy in vivo. Here we demonstrate how 3-D Fourier-domain resampling, in combination with high-speed optical coherence tomography (OCT), can achieve high-resolution in vivo tomography. Enhanced depth sensitivity was achieved over a depth-of-field extended in real time by more than an order of magnitude. This work lays the foundation for high-speed volumetric cellular-level tomography.
    Nature Photonics 06/2013; 7(6):444-448. · 27.25 Impact Factor
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    ABSTRACT: Hydrogel meets silicone: The chemical functionalization of a polydimethylsiloxane (PDMS) surface with polysaccharide "glue" induces a strong, permanent adhesion between the hydrogel and PDMS. This hydrogel-coated silicone substrate was useful for controlling cellular organization under mechanical stretching and also in fabricating microfluidic devices filled with the gel.
    Angewandte Chemie International Edition 05/2013; · 13.73 Impact Factor
  • Haohua Tu, Stephen A Boppart
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    ABSTRACT: Clinical translation of coherent anti-Stokes Raman scattering microscopy is of great interest because of the advantages of noninvasive label-free imaging, high sensitivity, and chemical specificity. For this to happen, we have identified and review the technical barriers that must be overcome. Prior investigations have developed advanced techniques (features), each of which can be used to effectively overcome one particular technical barrier. However, the implementation of one or a small number of these advanced features in previous attempts for clinical translation has often introduced more tradeoffs than benefits. In this review, we outline a strategy that would integrate multiple advanced features to overcome all the technical barriers simultaneously, effectively reduce tradeoffs, and synergistically optimize CARS microscopy for clinical translation. The operation of the envisioned system incorporates coherent Raman micro-spectroscopy for identifying vibrational biomolecular markers of disease and single-frequency (or hyperspectral) Raman imaging of these specific biomarkers for real-time in vivo diagnostics and monitoring. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
    Journal of Biophotonics 05/2013; · 3.10 Impact Factor

Publication Stats

7k Citations
897.39 Total Impact Points

Institutions

  • 2001–2014
    • University of Illinois, Urbana-Champaign
      • • Department of Electrical and Computer Engineering
      • • Beckman Institute for Advanced Science and Technology
      • • School of Chemical Sciences
      Urbana, Illinois, United States
  • 2012
    • Technical University of Denmark
      • Department of Photonics Engineering
      København, Capital Region, Denmark
  • 2006–2012
    • The Optical Society
      Society Hill, New Jersey, United States
  • 2011
    • Kyungpook National University
      • School of Computer Science and Engineering
      Taegu, Daegu, South Korea
  • 2010
    • Rice University
      Houston, Texas, United States
    • University of North Carolina at Chapel Hill
      • Department of Physics and Astronomy
      North Carolina, United States
  • 2008
    • Breast Cancer Prevention Institute
      Somerville, New Jersey, United States
  • 1996–2006
    • Massachusetts Institute of Technology
      • Department of Electrical Engineering and Computer Science
      Cambridge, MA, United States
  • 2000
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States
  • 1997–2000
    • Massachusetts General Hospital
      • Department of Medicine
      Boston, MA, United States
    • Duke University Medical Center
      • Department of Ophthalmology
      Durham, NC, United States