Gene Conte

Bio: Gene Conte is an academic researcher from General Electric. The author has contributed to research in topics: Superconducting magnet & Electromagnetic coil. The author has an hindex of 5, co-authored 6 publications receiving 95 citations.

Lightweight, compact, and high-performance 3T MR system for imaging the brain and extremities

Abstract: Purpose To build and evaluate a small-footprint, lightweight, high-performance 3T MRI scanner for advanced brain imaging with image quality that is equal to or better than conventional whole-body clinical 3T MRI scanners, while achieving substantial reductions in installation costs. Methods A conduction-cooled magnet was developed that uses less than 12 liters of liquid helium in a gas-charged sealed system, and standard NbTi wire, and weighs approximately 2000 kg. A 42-cm inner-diameter gradient coil with asymmetric transverse axes was developed to provide patient access for head and extremity exams, while minimizing magnet-gradient interactions that adversely affect image quality. The gradient coil was designed to achieve simultaneous operation of 80-mT/m peak gradient amplitude at a slew rate of 700 T/m/s on each gradient axis using readily available 1-MVA gradient drivers. Results In a comparison of anatomical imaging in 16 patients using T2 -weighted 3D fluid-attenuated inversion recovery (FLAIR) between the compact 3T and whole-body 3T, image quality was assessed as equivalent to or better across several metrics. The ability to fully use a high slew rate of 700 T/m/s simultaneously with 80-mT/m maximum gradient amplitude resulted in improvements in image quality across EPI, DWI, and anatomical imaging of the brain. Conclusions The compact 3T MRI system has been in continuous operation at the Mayo Clinic since March 2016. To date, over 200 patient studies have been completed, including 96 comparison studies with a clinical 3T whole-body MRI. The increased gradient performance has reliably resulted in consistently improved image quality.

Highly efficient head-only magnetic field insert gradient coil for achieving simultaneous high gradient amplitude and slew rate at 3.0T (MAGNUS) for brain microstructure imaging.

Abstract: Purpose To develop a highly efficient magnetic field gradient coil for head imaging that achieves 200 mT/m and 500 T/m/s on each axis using a standard 1 MVA gradient driver in clinical whole-body 3.0T MR magnet. Methods A 42-cm inner diameter head-gradient used the available 89- to 91-cm warm bore space in a whole-body 3.0T magnet by increasing the radial separation between the primary and the shield coil windings to 18.6 cm. This required the removal of the standard whole-body gradient and radiofrequency coils. To achieve a coil efficiency ~4× that of whole-body gradients, a double-layer primary coil design with asymmetric x-y axes, and symmetric z-axis was used. The use of all-hollow conductor with direct fluid cooling of the gradient coil enabled ≥50 kW of total heat dissipation. Results This design achieved a coil efficiency of 0.32 mT/m/A, allowing 200 mT/m and 500 T/m/s for a 620 A/1500 V driver. The gradient coil yielded substantially reduced echo spacing, and minimum repetition time and echo time. In high b = 10,000 s/mm2 diffusion, echo time (TE) 50% reduction compared with whole-body gradients). The gradient coil passed the American College of Radiology tests for gradient linearity and distortion, and met acoustic requirements for nonsignificant risk operation. Conclusions Ultra-high gradient coil performance was achieved for head imaging without substantial increases in gradient driver power in a whole-body 3.0T magnet after removing the standard gradient coil. As such, any clinical whole-body 3.0T MR system could be upgraded with 3-4× improvement in gradient performance for brain imaging.

The Cryogenics of a Thermosiphon-Cooled HTS MRI Magnet—Assembly and Component Testing

Abstract: The team at GE Global Research presents cryo assembly and component test results of a high-temperature superconducting (HTS) limb size magnetic resonance imaging (MRI) scanner using Sumitomo's DI-BSCCO tape conductor, under an NIH research grant. The goal is to investigate the thermosiphon behavior for different MRI operating modes, validating the cryogenic robustness of this cooling approach and its performance limits. The magnet is indirectly cooled using cooling tubes with liquid neon filling and a single-stage cryocooler for reliquefying.

Experimental Layer-Wound Mock-Up Coil for HTS MRI Magnet Using BSCCO Tape

Abstract: Typical coils with BSCCO tape are wound in a pancake or double-pancake style to minimize the strain in the tape by reducing or eliminating the edge-wise bending. Stainless steel reinforced tapes are frequently used in the winding process to increase the strength and reduce the strain due to winding tension and handling. However, an MRI magnet requires high current density in the winding pack. This high current density in the winding pack gives a higher field in the imaging volume and also allows for a reduction in the overall magnet size. Layer winding was preferred for a better tolerance control and for a reduction in the number of joints, which are known sources of resistance and therefore locations of instability in the coil. A mock-up coil was wound using a high-current-density type of BSCCO tape without the typical stainless steel reinforcement. The coil was layer-wound which involved a few inline lap joints embedded in the winding pack. The test of the coil reveals a few issues that need to be addressed. Investigations and analysis lead to a better understanding of the issues. This paper discusses the lessons learned and solutions for using non-reinforced tape in a layer-wound coil, while controlling insulation dimensions within the build.

BSCCO MRI Magnet Winding and Testing at ${\rm LN}_{2}$ Temperature

Abstract: A limb size MRI magnet coldmass has been constructed using DI-BSCCO tapes from Sumitomo. The coils were wound with epoxy pre-impregnated fiberglass cloth (pre-preg) between layers to bond the wires. For radial dimensional control, temperature was elevated during the winding to thin out the epoxy and to adjust the pre-preg cloth layer thickness in order to control the coil build up. The wire tension was controlled within 1 kg with a set of moving pulleys. While the coils appeared solid after winding and curing, issues were found in the leads between coils. When the coldmass was cooled down to liquid nitrogen temperature, breaks in wire leads were found. Thermal expansion and contraction mismatch between the coil bobbin and the BSCCO tape was attributed to the leads break. The thermal stress was induced both in the oven curing and the cooling processes. Preliminary testing results at temperature are discussed. The magnet was designed to have a center field of 1.5 T operating at a liquid neon (LNe) temperature of 27 K.

Recent Developments in High-Temperature Superconducting Magnet Technology (Review)

Abstract: The use of magnets made of high temperature superconductors (HTS) such as BSCCO and REBCO easily provide higher magnetic fields and higher operating temperatures, enabling dramatic improvements in superconducting magnet technology. The LTS magnet technology is very well summarized in text books written by M. N. Wilson (Superconducting magnets, Clarendon Press Oxford, 1983) and Y. Iwasa (Case studies in superconducting magnets, 2nd edition, Springer, 2009), covering such topics as stability, protection, ac loss and so forth. To the contrary, HTS conductors were commercialized only recently and therefore the magnet technology for HTS conductors remains undeveloped, especially so in the case of REBCO conductors. The technological problems for HTS coils thus far encountered are 1) an enormous effect of a screening current-induced magnetic field, 2) degradation in the coil performance due to excessive mechanical stresses applied along the longitudinal and transverse direction, and 3) the difficulty in protecting the magnet in the case of an abrupt thermal runaway. This paper reviews recent progress in overcoming these technological problems for HTS magnets. Both BSCCO and REBCO conductors have been used for HTS magnets in areas such as high field facilities, NMR, MRI, magnetic levitation trains and so forth. The effect of the screening current is the major problem for NMR, MRI, and accelerators, as it substantially distorts spatial field homogeneity and temporal field stability; on the other hand, degradation due to excessive stresses is substantial for high field magnets. Additionally, coil protection is a common and substantive problem among high current density HTS magnets in general. World-wide activities in developing BSCCO and REBCO magnets are overviewed in this paper.

Novel technologies and configurations of superconducting magnets for MRI

Abstract: A review of non-traditional approaches and emerging trends in superconducting magnets for MRI is presented. Novel technologies and concepts have arisen in response to new clinical imaging needs, changes in market cost structure, and the realities of newly developing markets. Among key trends are an increasing emphasis on patient comfort and the need for ?greener? magnets with reduced helium usage. The paper starts with a brief overview of the well-optimized conventional MR magnet technology that presently firmly occupies the dominant position in the imaging market up to 9.4?T. Non-traditional magnet geometries, with an emphasis on openness, are reviewed. The prospects of MgB2 and high-temperature superconductors for MRI applications are discussed. In many cases the introduction of novel technologies into a cost-conscious commercial market will be stimulated by growing needs for advanced customized procedures, and specialty scanners such as orthopedic or head imagers can lead the way due to the intrinsic advantages in their design. A review of ultrahigh-field MR is presented, including the largest 11.7?T Iseult magnet. Advanced cryogenics approaches with an emphasis on low-volume helium systems, including hermetically sealed self-contained cryostats requiring no user intervention, as well as future non-traditional non-helium cryogenics, are presented.

A Study on the No Insulation Winding Method of the HTS Coil

Abstract: This paper reports a study on BSCCO and ReBCO HTS (high temperature superconducting) test coils, layer-wound and double-pancake, with and without turn-to-turn insulation. Over current tests were performed in a bath of liquid nitrogen to compare stabilities of the test coils at 77 K. Saturation of magnetic fields from the NI (no insulation) coils, both BSCCO and ReBCO, was observed owing to current bypassing through turn-to-turn contacts in local quenches at operating currents higher than their critical currents. In the NI ReBCO coils, global quenches occurred at operating currents higher than the coil critical currents and quench recoveries were observed during discharge of the coils. The experimental results, obtained to date, demonstrate that the NI winding method enables remarkable improvement of thermal stability of the HTS coils.

Accessible magnetic resonance imaging: A review.

Abstract: The role of MRI in diagnostics, prognostics, and discoveries in basic sciences has been well established. However, access to this life-saving technology is largely restricted to countries in upper-middle to high-income groups. In this article, we collate recent global MR scanner density data and group them into six geographical regions based on the WHO classification. We then analyze these data with respect to demographic factors such as population size, life expectancy, the percentage of internet users, and World Bank income grouping. We map these demographic factors to five dimensions or characteristics of accessible MRI, adapting definitions from the healthcare literature. With this background, the study then reviews recent demonstrations of accessible MRI categorized based on main magnetic field strength. We describe demonstrated examples for each of these categories, ranging from ultralow-field to ultrahigh-field MRI. Lastly, we review MR methods and associated developments impacting accessible MRI such as increasing/augmenting MR awareness and local expertise, incorporating hardware-cognizant methods, rapid quantitative imaging, and leveraging innovations from adjacent fields. Level of Evidence: 5 Technical Efficacy Stage: 6 J. Magn. Reson. Imaging 2019.

A portable scanner for magnetic resonance imaging of the brain.

Abstract: Access to scanners for magnetic resonance imaging (MRI) is typically limited by cost and by infrastructure requirements. Here, we report the design and testing of a portable prototype scanner for brain MRI that uses a compact and lightweight permanent rare-earth magnet with a built-in readout field gradient. The 122-kg low-field (80 mT) magnet has a Halbach cylinder design that results in a minimal stray field and requires neither cryogenics nor external power. The built-in magnetic field gradient reduces the reliance on high-power gradient drivers, lowering the overall requirements for power and cooling, and reducing acoustic noise. Imperfections in the encoding fields are mitigated with a generalized iterative image reconstruction technique that leverages previous characterization of the field patterns. In healthy adult volunteers, the scanner can generate T1-weighted, T2-weighted and proton density-weighted brain images with a spatial resolution of 2.2 × 1.3 × 6.8 mm3. Future versions of the scanner could improve the accessibility of brain MRI at the point of care, particularly for critically ill patients. A portable prototype scanner for brain MRI that uses a compact and lightweight permanent rare-earth magnet with a built-in readout field gradient generates clinically relevant images of the brain, as shown in adult volunteers.