RF-Pulses: Design and Applications

June 13-15, 2019

 

Zurich/CH

 

Course organisers

Martin Haas
Bruker BioSpin MRI GmbH
Ettlingen/DE

Franciszek Hennel
Institute for Biomedical Engineering (IBT)
University and ETH Zurich/CH

Local organisers

Franciszek Hennel, Markus Weiger
Institute for Biomedical Engineering (IBT)
University and ETH Zurich/CH

Course venue

Institute for Biomedical Engineering (IBT)
University and ETH Zurich/CH

Hotel Information

tba

Registration Fees

Early Registration Fee
(until 8 weeks prior to the course)

Regular fee

ESMRMB Members* € 420
ESR Members* € 530
Non-Members € 600

Reduced fee**
Juniors, Radiographers, Seniors

ESMRMB Members* € 300
ESR Members* € 325
Non-Members € 350

Late Registration Fee
(after 8 weeks prior to the course)

Regular fee

ESMRMB Members* € 560
ESR Members* € 670
Non-Members € 740

Reduced fee**
Juniors, Radiographers, Seniors

ESMRMB Members* € 400
ESR Members* € 425
Non-Members € 450

 

Preliminary Faculty

M. Haas, F. Hennel, J. Hennig, U. Katscher, R. Schulte, J. Warnking

Programme

The programme of the course will be announced soon!

Goals of the course

Radio frequency (RF) pulses are the tool by which nuclear spins are forced to do their “gymnastics” which reveals to us the internal structure of bodies and molecules in MRI and NMR experiments. Their properties determine many essential quality and safety aspects of MR techniques, such as the precision of slice selection, homogeneity of image contrast, efficiency of spectral suppression or the Specific Absorption Rate (SAR). A good understanding of how RF pulses act on the spins, how they should be chosen and how they can be designed is a great asset for all MR scientists seeking a full control of the instruments they use.

The aim of the course is to provide an in-depth insight into the design and usage of RF pulses in magnetic resonance imaging. Starting from a basic introduction to the physics of RF interaction with the spin system, the course will cover the major pulse design and calculation techniques and  provide guidance how to choose suitable pulses in common MRI sequences. A special emphasis will also be put on the design and applications of so-called multidimensional RF pulses, particularly in combination with the concept of parallel RF transmission.

 

The course will cover

  • Introduction to the physics and technical aspects of RF pulses
  • Calculation of RF pulses in the Small-Tip-Angle approximation
  • Calculation methods for Large-Tip-Angle pulses: The Shinnar-Le-Roux and the Optimal-Control approach
  • Which RF pulse to choose for which function in common MRI sequences
  • Special purpose RF pulses
  • Multidimensional RF pulses: Localisation and modulation of the transverse magnetisation in more than one dimension
  • Parallel Excitation/Transmit SENSE: How the world of multidimensional pulses changes with the introduction of new degrees of freedom by multiple transmission channels
Educational level

This course is intended for MR physicists, other scientists and PhD students who already have experience in basic MR methods, and who wish to expand their knowledge in the field of RF pulse design and applications. The three-day course will consist of different thematic modules, ranging from a basic introduction into RF pulse physics up to advanced techniques. Each module will be divided into a lecture presenting the subject matter of the module and exercises with audience participation aiming at a deeper understanding of the key aspects of the lecture.

Course description

This course provides an in-depth introduction to basic and advanced RF pulse design methods and applications. It is intended for MR physicists, other scientists and PhD students who already have experience in basic MR methods and who wish to expand their knowledge in the field of RF pulse design and applications.

The course will start with an introduction to the physics and technical aspects of RF pulses and explain the basic design methods for RF pulses in the Small-Tip-Angle approximation as well as their limitations. Addressing these limitations the next module will present principles and properties of calculation techniques for Large-Tip-Angle pulses. Based on these foundations, a module will follow focusing on the different functions RF pulses can play in MRI sequences and examples regarding the proper choice of RF pulses for common MRI sequences will be discussed. A further module will give some insight into selected applications using special purpose RF pulses. The final part of the course will lead into the area of multidimensional selective pulses including a module focusing on the rapidly evolving field of parallel transmission pulses.

Each module of the three-day course will consist of a lecture presenting the subject matter of the module and of accompanying exercises with audience participation, in order to deepen the understanding of the key aspects of the lecture. On the last day of the course, a hands-on workshop will take place in the computer lab, in which the participants can choose from MATLAB exercises related to the course modules. These exercises can then be solved in small groups in individual time and with as much faculty support as needed.

Learning objectives

Basic RF pulse physics

  • Interaction of RF with the spins: From quantum mechanics to classical view
  • Frequency-selective pulses in Small-Tip-Angle (STA) approximation
  • Combination of RF pulses and 1D gradients: Slice selection
  • Excitation k-space (in 1D)
  • Focus and effective phase of selective pulses
  • Safety aspects: Specific Absorption Rate (SAR)
  • SAR reduction with the VERSE principle

Large-Tip-Angle pulses

  • Introduction into calculation methods for Large-Tip-Angle (LTA) pulses
    • Shinnar-Le-Roux approach
    • Optimal-Control approach

Which RF pulse should I choose for which function in my sequence?

  • RF pulse functions:
    • Excitation pulses
    • Refocusing pulses
    • Inversion pulses
  • What are the requirements for the different functions?
  • Which pulse shapes are suitable for the different functions and why?
  • Examples regarding major MRI sequences

Special purpose

RF pulses

  • Adiabatic pulses
  • Multislice pulses
  • Half pulses
  • Composite pulses

Multidimensional RF pulses

  • Multidimensional spatially selective excitation (SSE): Localisation of the excitation in more than one dimension
  • Multidimensional excitation k-space
  • RF pulse calculation for multidimensional SSE in the STA and LTA
  • Spectral-spatial RF pulses
  • Applications of multidimensional RF pulses

Parallel RF transmission

  • From multidimensional excitation to parallel excitation/ transmit SENSE: Introducing new degrees of freedom
  • Pulse calculation for parallel excitation in contrast
  • to pulse calculation for SSE: New opportunities – new challenges
  • Application perspectives of parallel transmission
  • SAR and parallel transmission

Hands-on workshop

  • Simulation of RF pulses
  • Getting an intuitive understanding of the effects of RF pulses on spins
  • Designing various RF pulses
  • Understanding trade-offs in RF design