BURLINGTON, MA, United States
BURLINGTON, MA, United States
SEARCH FILTERS
Time filter
Source Type

Khan S.,Dartmouth College | Manwaring P.,Dartmouth College | Manwaring P.,Domain Surgical | Borsic A.,Dartmouth College | And 2 more authors.
IEEE Transactions on Medical Imaging | Year: 2015

Electrical impedance tomography (EIT) is used to image the electrical property distribution of a tissue under test. An EIT system comprises complex hardware and software modules, which are typically designed for a specific application. Upgrading these modules is a time-consuming process, and requires rigorous testing to ensure proper functioning of new modules with the existing ones. To this end, we developed a modular and reconfigurable data acquisition (DAQ) system using National Instruments' (NI) hardware and software modules, which offer inherent compatibility over generations of hardware and software revisions. The system can be configured to use up to 32-channels. This EIT system can be used to interchangeably apply current or voltage signal, and measure the tissue response in a semi-parallel fashion. A novel signal averaging algorithm, and 512-point fast Fourier transform (FFT) computation block was implemented on the FPGA. FFT output bins were classified as signal or noise. Signal bins constitute a tissue's response to a pure or mixed tone signal. Signal bins' data can be used for traditional applications, as well as synchronous frequency-difference imaging. Noise bins were used to compute noise power on the FPGA. Noise power represents a metric of signal quality, and can be used to ensure proper tissue-electrode contact. Allocation of these computationally expensive tasks to the FPGA reduced the required bandwidth between PC, and the FPGA for high frame rate EIT. In 16-channel configuration, with a signal-averaging factor of 8, the DAQ frame rate at 100 kHz exceeded 110 frames s-1, and signal-to-noise ratio exceeded 90 dB across the spectrum. Reciprocity error was found to be < 1\% for frequencies up to 1 MHz. Static imaging experiments were performed on a high-conductivity inclusion placed in a saline filled tank; the inclusion was clearly localized in the reconstructions obtained for both absolute current and voltage mode data. © 2014 IEEE.


Adolphi N.L.,University of New Mexico | Huber D.L.,Sandia National Laboratories | Bryant H.C.,Ne Scientific, Llc | Monson T.C.,Sandia National Laboratories | And 11 more authors.
Physics in Medicine and Biology | Year: 2010

Optimizing the sensitivity of SQUID superconducting quantum interference device) relaxometry for detecting cell-targeted magnetic nanoparticles for in vivo diagnostics requires nanoparticles with a narrow particle size distribution to ensure that the Néel relaxation times fall within the measurement timescale 50 ms-2 s, in this work). To determine the optimum particle size, single-core magnetite nanoparticles with nominal average diameters 20, 25, 30 and 35 nm) were characterized by SQUID relaxometry, transmission electron microscopy, SQUID susceptometry, dynamic light scattering and zeta potential analysis. The SQUID relaxometry signal detected magnetic moment/kg) from both the 25 nm and 30 nm particles was an improvement over previously studied multicore particles. However, the detected moments were an order of magnitude lower than predicted based on a simple model that takes into account the measured size distributions but neglects dipolar interactions and polydispersity of the anisotropy energy density), indicating that improved control of several different nanoparticle properties size, shape and coating thickness) will be required to achieve the highest detection sensitivity. Antibody conjugation and cell incubation experiments show that single-core particles enable a higher detected moment per cell, but also demonstrate the need for improved surface treatments to mitigate aggregation and improve specificity. © 2010 Institute of Physics and Engineering in Medicine.


Branson B.M.,Ne Scientific, Llc
Current HIV/AIDS Reports | Year: 2015

Numerous improvements in HIV testing technology led recently to the first revision of recommendations for diagnostic laboratory testing in the USA in 25 years. Developments in HIV testing continue to produce tests that identify HIV infection earlier with faster turnaround times for test results. These play an important role in identifying HIV infection during the highly infectious acute phase, which has implication for both patient management and public health interventions to control the spread of HIV. Access to these developments, however, is often delayed by the regulatory apparatus for approval and oversight of HIV testing in the USA. This article summarizes recent developments in HIV diagnostic testing technology, outlines their implications for clinical management and public health, describes current systems of regulatory oversight for HIV testing in the USA, and proposes alternatives that could expedite access to improved tests as they become available. © 2015, Springer Science+Business Media New York.


Bryant H.C.,Ne Scientific, Llc | Bryant H.C.,University of New Mexico | Adolphi N.L.,Ne Scientific, Llc | Adolphi N.L.,University of New Mexico | And 5 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2011

We use dynamic susceptometry measurements to extract semiempirical temperature-dependent, 255400 K, magnetic parameters that determine the behavior of single-core nanoparticles useful for SQUID relaxometry in biomedical applications. Volume susceptibility measurements were made in 5 K degree steps at nine frequencies in the 0.11000 Hz range, with a 0.2 mT amplitude probe field. The saturation magnetization (M s) and anisotropy energy density (K) derived from the fitting of theoretical susceptibility to the measurements both increase with decreasing temperature; good agreement between the parameter values derived separately from the real and imaginary components is obtained. Characterization of the Nel relaxation time indicates that the conventional prefactor, 0.1 ns, is an upper limit, strongly correlated with the anisotropy energy density. This prefactor decreases substantially for lower temperatures as K increases. We find, using the values of the parameters determined from the real part of the susceptibility measurements at 300 K, that SQUID relaxometry measurements of relaxation and excitation curves on the same sample are well described. © 2010 Elsevier B.V. All rights reserved.


Borsic A.,Ne Scientific, Llc | Hoffer E.,Dartmouth Hitchcock Medical Center | Attardo E.A.,Ne Scientific, Llc
Proceedings of the IEEE Annual Northeast Bioengineering Conference, NEBEC | Year: 2014

In this paper we present results showing that Graphic Processing Units (GPUs) can be used to accelerate the simulation of the thermal field dose during Radio Frequency Ablation (RFA). Specifically we show that this simulation can be conducted in real-time, allowing the development of intraoperative guidance platforms that track and display the thermal lesion as it forms during the intervention. Real time simulation has not been reported before, and has been a critical factor preventing development of intraoperative guidance tools. © 2014 IEEE.


Borsic A.,Ne Scientific, Llc | Perreard I.,Dartmouth Hitchcock Medical Center | Mahara A.,Dartmouth College | Halter R.J.,Dartmouth College
IEEE Transactions on Medical Imaging | Year: 2016

Magnetic Resonance-Electrical Properties Tomography (MR-EPT) is an imaging modality that maps the spatial distribution of the electrical conductivity and permittivity using standard MRI systems. The presence of a body within the scanner alters the RF field, and by mapping these alterations it is possible to recover the electrical properties. The field is time-harmonic, and can be described by the Helmholtz equation. Approximations to this equation have been previously used to estimate conductivity and permittivity in terms of first or second derivatives of RF field data. Using these same approximations, an inverse approach to solving the MR-EPT problem is presented here that leverages a forward model for describing the magnitude and phase of the field within the imaging domain, and a fitting approach for estimating the electrical properties distribution. The advantages of this approach are that 1) differentiation of the measured data is not required, thus reducing noise sensitivity, and 2) different regularization schemes can be adopted, depending on prior knowledge of the distribution of conductivity or permittivity, leading to improved image quality. To demonstrate the developed approach, both Quadratic (QR) and Total Variation (TV) regularization methods were implemented and evaluated through numerical simulation and experimentally acquired data. The proposed inverse approach to MR-EPT reconstruction correctly identifies contrasts and accurately reconstructs the geometry in both simulations and experiments. The TV regularized scheme reconstructs sharp spatial transitions, which are difficult to reconstruct with other, more traditional approaches. © 2015 IEEE.


Johnson C.,Sandia National Laboratories | Adolphi N.L.,University of New Mexico | Butler K.L.,University of New Mexico | Lovato D.M.,University of New Mexico | And 3 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2012

Magnetic relaxometry methods have been shown to be very sensitive in detecting cancer cells and other targeted diseases. Superconducting quantum interference device (SQUID) sensors are one of the primary sensor systems used in this methodology because of their high sensitivity with demonstrated capabilities of detecting fewer than 100,000 magnetically-labeled cancer cells. The emerging technology of atomic magnetometers (AMs) represents a new detection method for magnetic relaxometry with high sensitivity and without the requirement for cryogens. We report here on a study of magnetic relaxometry using both AM and SQUID sensors to detect cancer cells that are coated with superparamagnetic nanoparticles through antibody targeting. The AM studies conform closely to SQUID sensor results in the measurement of the magnetic decay characteristics following a magnetization pulse. The AM and SQUID sensor data are well described theoretically for superparamagnetic particles bound to cells and the results can be used to determine the number of cells in a cell culture or tumor. The observed fields and magnetic moments of cancer cells are linear with the number of cells over a very large range. The AM sensor demonstrates very high sensitivity for detecting magnetically labeled cells, does not require cryogenic cooling and is relatively inexpensive. © 2012 Elsevier B.V.


PubMed | Ne Scientific, Llc
Type: Journal Article | Journal: Current HIV/AIDS reports | Year: 2015

Numerous improvements in HIV testing technology led recently to the first revision of recommendations for diagnostic laboratory testing in the USA in 25years. Developments in HIV testing continue to produce tests that identify HIV infection earlier with faster turnaround times for test results. These play an important role in identifying HIV infection during the highly infectious acute phase, which has implication for both patient management and public health interventions to control the spread of HIV. Access to these developments, however, is often delayed by the regulatory apparatus for approval and oversight of HIV testing in the USA. This article summarizes recent developments in HIV diagnostic testing technology, outlines their implications for clinical management and public health, describes current systems of regulatory oversight for HIV testing in the USA, and proposes alternatives that could expedite access to improved tests as they become available.


Borsic A.,Ne Scientific, Llc | Helisch A.,Dartmouth Hitchcock Medical Center
Proceedings of the IEEE Annual Northeast Bioengineering Conference, NEBEC | Year: 2014

In this paper we present results relative to speeding up multiscale vessel enhancement filters for angiography images by using Graphic Processing Units (GPUs). These filters, proposed initially by Frangi [1], can be used to preferentially enhance image features that have a tubular-like structure, and therefore result in the enhancement of vessels. Vessel enhancement filters are used commonly as a pre-processing step for vessel segmentation. As this process is computationally and memory intensive, filtering high-resolution 3D micro-CT (mCT) images can take several hours. We propose a method for speeding up this process using GPUs which results in significant speed gains and which is memory efficient. © 2014 IEEE.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 218.46K | Year: 2014

DESCRIPTION (provided by applicant): The objective of this proposed research program is to develop a platform for planning and guidance during Radio Frequency Ablation (RFA). RFA is a thermally mediated ablation technique, where an applicator carrying oneelectrode is inserted into tumors percutaneously (or via laparoscopy, or open surgical approaches). Radio Frequency (RF) energy is applied, denaturating and coagulating tissues in a volume of 2cm to 5cm of diameter. Some RFA electrodes are shaped as straight needles; others deploy an umbrella of tines to ablate a larger volume. RFA is attractive as it can be used percutaneously resulting minimally invasive. RFA is a widely accepted cancer treatment therapy, and is applied to primary and secondary tumors indifferent organs, including liver, lung, kidney, breast, and in musculoskeletal interventions. RFA is often the preferred treatment option for inoperable patients. The typical approach for RFA is percutaneous. Physicians therefore have no direct view of th

Loading Ne Scientific, Llc collaborators
Loading Ne Scientific, Llc collaborators