RF Design Suite

“You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.”Albert Einstein

MRI systems are largely built upon great deal of Radio Frequency (RF) technology and applied electromagnetics concepts encompassing transmitters, heterodyne receivers, coils/resonators, etc. The performance of RF coils and peripheral subsystems are key to the optimal operation of MRI systems. A well equipped MR system may typically rely on a dozen or more RF transmitters, receivers, and coils serving for the optimal collection of data in application specific experiments. This may include anatomically specific locations and/or different animal species. The CFMM has a long history in hardware and RF coil development and, since the establishment of the centre in 1996, have been designing and building RF coils and receiver chain subsystems for a wide variety of experiments.

 

The Team & Mission

Our philosophy embraces continuous research and development dedicated to advance the efficacy of high-field MRI technology. Pushing the frontier in RF design for high-field MRI towards higher image fidelity, lower operational costs, and broader utility is our quest in the RF design suite. Our team specializes in designing, developing and commissioning state-of-the-art RF solutions for high-field MRI scanners, e.g., 3T, 7T, 9.4T and beyond. Whether there are no commercial-off-the-shelf (COTS) RF systems available to meet the operational requirements, or otherwise they fail to achieve that end, we develop superior systems based on innovative and cost saving design concepts.

Our team at the RF design suite is committed to innovation in developing RF solution concepts, perfection in building system prototypes for feasibility studies, thoroughness in conducting comparative investigations. Our systems are founded on conducting thorough design-for-manufacturability (DFM) assessment, evaluating COTS parts, exerting design-for-testability (DFT) techniques, and producing bills of material based on cost-to-performance analysis.

Our areas of expertise include:

  • RF coil design (volume, surface, tunable, etc). Specifically, our team is expert in multi-channel transmit arrays at high and ultra-high fields.
  • Gradient coil design
  • RF measurements and instrumentation (e.g., power measurements, network analysis, noise-figure measurements, electric and magnetic field spatial distribution mapping, time-domain reflectometry, dielectric measurements, etc)
  • RF system design (e.g., PLL, direct conversion and heterodyne receivers, high power TR switches, high-speed TR drivers, low noise amplifiers)
  • Numerical electromagnetic modeling

Facilities and Equipments

The RF suite is situated in the heart of the CFMM serving both the 3T/7T and 9.4 T MRI suites. The RF suite itself is well equipped with state-of-the-art instrumentation making RF device development, construction and servicing convenient. The equipment housed in the suite include vector network analyzers, impedance analyzers, noise figure analyzer, spectrum analyzers, digital oscilloscopes, frequency generators, material measurement systems, power supplies and a myriad of tools necessary for any sophisticated RF project. CFMM has access to variety of advanced electrical and mechanical manufacturing facilities. The suite is equipped with various CAD tools for mechanical modeling (Solidworks and MasterCam), schematic capture/printed circuit board (PCB) design, (Altuim Designer), measurement automation and data acquisition, (Labview and Matlab), full-wave numerical electromagnetic modeling/analysis, (CST). An NC mill and machine shop, housed in the basement of the facility, serves as an extension to the RF suite giving us complete electro-mechanical capability in RF coil/system production.

 

Developed Coils and Systems

RF Coils:

  • 7 Tesla 15-channel-transmit coil integrated with 23-channel phased array receive coil for human brain imaging (elliptical)
  • 7 Tesla 16-channel-transmit coil integrated with 16-channel phased array receive coil for human brain imaging (cylindrical)
  • 16 Channel Head Coil: Transmit-receive surface coil for human brain imaging at 7T (cylindrical)
  • 5 Channel Primate Coil : Transmit-receive surface coils for primate head imaging at 7T
  • Multi-nuclear transmit receive arrays (Proton, 23Na, 31P, 17O, etc)
  • Small animal coils for 9.4T system

RF Subsystems:

  • Automated eddy current-induced Bo-shift compensation using frequency modulation
  • 7T electronics upgrade to enable transmit-only-receive-only RF capability which included integrating preamp bias circuits and diode drivers into modular RF coil interface
  • 10-400 MHz 36 Channel Peak & Average Power Meter: high dynamic range power monitoring system for MRI scanners to insure SAR levels are within the FDA regulation limits.
  • High Power narrow band TR Switch banks
  • 40-300 MHz High Power TR Switch – Low-Noise Amplifier Modules: a compact low-noise MRI receiver front-end which departs from the conventional and limiting quarter-wave switch design.

Consulting / Collaboration

Whether it is a specific RF design problem or a potential concept you want to validate, feel free to discuss it with us.