xMR
Research
Laboratories

MRI Systems Development

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  • Gradient coil design and construction
  • Shim coil design and construction
  • RF coil design and construction
  • Peripheral nerve stimulation from gradient fields
  • Acoustic noise produced from gradient coils
  • Medical Device Compatibility Testing

  • dB/dt exposure device design and construction
  • Device vibration within rapidly switching magnetic fields
  • Device torque and displacement within a static magnetic field
  • Device heating within a RF field
  • Electromagnetic Modelling and Simulation

  • Material interactions within a static magnetic field
  • RF exposure on a realistic human model
  • MRI Systems Development

    Gradient Coil Design & Construction

    We have amassed experience in both design and manufacture of gradient coils for MRI systems, building approximately 10 prototypesin the last decade. Design methods, largely building on the PhD work of Chad Harris which used the Boundary Element Method are still being developed and are used extensively in house.

    The use of the Boundary Element Method has allowed the design process to move away from the limitations imposed on magnet design in the past, such as a cylindrical coil or a centered target fieldregion, and instead calculate the optimum wire pattern to achieve a broad array of design goals. Importantly, manufacturing techniques and methods are taken into account at the design level, to reduce costs and time of the gradient construction, and to control the tolerances of the system and get a superior final result.

    We continue to design and build gradient coils for multiple partners and will be pushing the envelope for electromagnetic and thermal performance as we implement new methods and ideas.

    RF Systems Design

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    Shim Coil

    Shim Coil Development

    Shimming magnetic fields, statically and dynamically is a necessary part of performing high quality magnetic resonance images. The Boundary Element Method is used to discover the wire patterns and to minimize the coupling between all other magnets in the system at the design stage, allowing us a high degree of flexibility. Shim coils are constructed with various manufacturing methods, depending upon the needs of the project and are constructed with a high tolerance.

    Modeling & Simulation

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    Using computational electromagnetics we can better understand the effects and potential dangers of medical device implants inside an MRI. This image demonstrates a calculation of human tissue heating around a sample passive medical device implant within an MRI system. These simulations allow us to give feedback for the development of safer medical implants.

    MR Application Development

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    Medical Device Testing

    Our lab specializes in performing MR safety tests in accordance with ISO 10974.

    Thermal Imaging Camera

    dB/dt Exposure

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    Rapidly changing gradient magnetic fields can induce eddy currents in metallic devices which can cause significant heating. Our lab has designed and built various sized dB/dt exposure systems for various device sizes and needs. We also have a thermal camera and fiber optic probes to measure temperature changes throughout standard exposure levels.

    Device Vibration

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    Our lab is equipped to measure vibration in an MR scanner to micrometer precision using both a laser Doppler vibrometer and piezoelectric accelerometers. Device vibration is measured during exposure to varying gradient frequencies along a single axis. The device is placed in a high dB/dt location in the scanner to observe worst-case scenario.

    When a conductive device is exposed to a changing gradient field inside a constant magnetic field, there is potential for vibration. We use miniature piezoelectric accelerometers and a laser Doppler vibrometer to measure device movement when exposed to worst-case scenarios in an MRI scanner. Typically, gradient pulse exposures consist of sinusoid or trapezoidal gradient pulses. To measure worst case scenarios, the devices are typically placed in a scanner location with a maximum dB/dt.

    Torsion & Displacement

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    RF Heating

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    Image Distortion

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    Ambient Electromagnetics

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