ISMRM 24th Annual Meeting & Exhibition 07-13 May 2016 Singapore

Weekend Educational Course: RF Engineering: Coils

Skill Level: Intermediate

Organizers: Nicola De Zanche, Ph.D. & Graham C. Wiggins, D.Phil.

Sunday 08 May 2016

In this one-day course, the principles of RF coils used to detect and excite the MR signals will be discussed, beginning with the transmission lines that interconnect the coils to the MR system, and extending to single surface and volume coils and finally RF coil arrays for both transmit and receive. A discussion of the RF modeling tools used to analyze these coils and coil arrays, and their interaction with the patient and the environment will lead into the interaction of RF fields with other objects in the MR environment.

Target Audience
This course is designed for MR technicians, scientists and engineers with an interest in understanding physical principles behind MR safety issues related to RF fields, and/or the construction, design or use of RF coils and RF coil arrays.

Educational Objectives
Upon completion of this course, participants should be able to:

  • Describe the basic theory, design and construction of single and multi-tuned RF coils and their feed networks;
  • Illustrate the principles of operation and basic applications of receive and transmit RF coil arrays; and
  • Compare the major methods of RF modeling commonly in use and the relative advantages and disadvantages of each.

Moderators: John Andrew Derbyshire, Graham Wiggins
      RF Basics  
Basics of Transmission Lines & Power Transfer
Natalia Gudino1
1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Strokes, NIH, Bethesda, MD, United States
Fundamentals of transmission lines and power transfer are presented to help in the understanding, design, implementation and performance evaluation of MRI hardware.

Volume & Surface Coils
Bei Zhang1
1Department of Radiology, The Bernard and Irene Schwartz Center for Biomedical Imaging, New York, NY, United States
Highlights: RF coils are an essential part of a MRI system to excite and receive MR signals. Their performance is very important for the quality of MR imaging.

Volume coils provide relatively uniform sensitivity over a large volume.

Surface coils are designed to maximize SNR and enable parallel imaging

Volume coils and surface coils usually work together in the RF system to optimize the RF excitation and reception performances at the same time

Decoupling technologies are needed in the design to minimize coupling between transmit and receive coil elements

Multi-Tuned Coils - Permission Withheld
Ryan Brown1
1Radiology, New York University School of Medicine, New York, NY, United States
Dual-tuned coils provide metabolic information (x-nuclei module) and co-registered anatomical images and B0 shim settings (1H module) and without repositioning the subject or coil. X-nuclei signal strength is typically less than 1/1,000 that of 1H (1). Therefore it is important to maximize x-nuclei receive sensitivity while simultaneously providing adequate 1H sensitivity. We will discuss prevalent dual-tuning techniques and considerations for performance characterization and interfacing dual-tuned coils.

Break & Meet the Teachers
      RF Arrays  
Receive Arrays & Circuitry
Boris Keil
Transmit Arrays & Circuitry
Yeun Chul Ryu1
1Radiological Science, Gachon University, Incheon, Korea, Republic of
Transmit arrays enable finer RF driving over the RF field distribution in exciting the MR signals.

In this session the following issues will be introduced.

- Transmit Arrays

- Decoupling and Matching/Tuning Techniques for Multi-element coil

- Individually Driven Coil Element

- SAR and Tissue Heating

RF Modelling
Feng Liu1
1The University of Queensland, Australia
RF modelling is now routinely performed in the design and analysis of MRI RF systems. This talk shares insights into technical details of implementing the most popular numerical electromagnetic (EM) methods. In particular, hybrid full-wave EM methods and parallel computing are highlighted, which creates a powerful theoretical prototyping platform for the design of novel RF coil systems. It is hoped that this talk can aid those who intend to implement demanding computational experiments for the research and development of RF coil designs for high-field MRI applications.  

Lunch & Meet the Teachers
      Emerging RF Coils & Technologies  
Dielectric Materials & Resonators
Sebastian Aussenhofer
This session explains the source of dielectric effects in MRI. It is furthermore explained how the dielectric effects can be used to improve image and spectra quality.

Dipoles & Traveling Waves
David Brunner1
1Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
NMR and MRI signal detection is traditionally based on Faraday induction. The local magnetic moment produced by the nuclear spins is thereby excited and detected by near-field magnetic interaction with the coil. However, the basic physical regime governing the electrodynamics of the RF detector alters at ultra-high frequencies and therefore the instruments applied in these systems have to cope with a different situation than at lower field strengths. The emergence of field propagation phenomena and radiation allows and necessitates the application of new RF topologies that are not only targeted at producing and detecting magnetic fields in their reactive near field.

Break & Meet the Teachers
      Live Construction of Coils  
Construction of Rx Arrays
Ewald Weber1 and Yu Li2
1ITEE - Biomedical Engineering, The University of Queensland, St Lucia, Brisbane, Australia, 2ITEE- Biomedical Engineering, The University of Queensland, St Lucia, Brisbane, Australia
In this live demonstration of RF coil construction, we will first present general RF-coil construction methods and some useful accessories and tools built in our lab. We will then guide the audience through all main design and construction steps while building a simple (but rather unconventional) Rx array. We will show some alternative decoupling techniques (not relying on preamplifier decoupling) to compensate mutual inductance and minimise coil-coil coupling. The presented methods will be easily applicable to construct other simple RF coil arrays, including Tx/Rx arrays. Finally, we will present some imaging results on a human wrist using this array.

Adjournment & Meet the Teachers

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.