ISMRM22 - MR Physics & Engineering II: Lost in k-Space?

Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting • 07-12 May 2022 • London, UK

MR Physics & Engineering II: Lost in k-Space?

Weekend Course

ORGANIZERS: Sune Jespersen, Philipp Ehses, Mark Ladd, Rita Schmidt

Saturday, 07 May 2022

N11 (Breakout A)

13:00 - 17:00

Moderators:
Imaging Principles: Mariya Doneva
RF Pulses: S. Johanna Vannesjo
Pulse Sequences: Martijn Cloos
Contrast Generation: Benedikt Poser

Skill Level: Basic to Intermediate

Session Number: WE-14

Session Number: WE-14

Overview
This course builds on the foundations laid out in MR Physics & Engineering I. Spatial encoding and k-space are introduced, and a detailed analysis of RF pulse effects and design is presented. Attendees are given an overview of how to generate various types of image contrasts that reflect different physical properties, and the two main types of MRI sequences, gradient echo and spin-echo, will be discussed in depth in their various incarnations. We will also discuss signal and noise properties and the impact of acquisition parameters.

Target Audience
Physicists and engineers interested in learning or refreshing the foundations of MRI.

Educational Objectives
As a result of attending this course, participants should be able to:
- Formulate the principles of spatial encoding;
- Analyze the effects of k-space sampling;
- Evaluate signal-to-noise (SNR);
- Analyze the impact of acquisition parameters on SNR;
- Analyze and design pulse shapes based on common concepts and algorithms such as excitation k-space and Shinnar-Le Roux;
- Explain differences between common gradient-echo and spin-echo techniques; and
- Adapt the image contrast by including a magnetization preparation in a pulse sequence.

	Imaging Principles
13:00		Spatial Encoding in MRI View the Presentation Andrada Ianus This talk will cover the basics of spatial encoding in MRI. Using magnetic field gradients for spatial encoding: slice selection, frequency and phase encoding. Fourier relationship between image space and k-space. Intuitive description of k-space and it's link to spatial frequencies in the image. Properties of k-space. Different readout strategies: multi-shot, single shot, cartesian, non-cartesian, etc.
13:30		Signal & Noise View the Presentation Olaf Dietrich The signal-to-noise ratio (SNR) in MRI: definition of SNR analyzing the impact of acquisition parameters on SNR analyzing noise and signal statistics evaluating the SNR in MRI
	RF Pulses
14:00		RF Pulses View the Presentation Zhiyong Zhang The goal of the talk is educational for basis concepts of RF pulse design including the basic properties of RF pulses (the flip angle, duration, and amplitude) as well as the concepts to understand the theory and implementation of RF pulses using the small tip angle tip angle approximations. The talk covers topics such as spatial localization, SLR pulses, adiabatic pulses, multi-band pulses and spatial-spectral pulses.
14:30		Interactive Session
15:00		Break & Meet the Teachers
	Pulse Sequences
15:30		Design of Gradient-Echo Sequences View the Presentation Rahel Heule Signal generation in magnetic resonance imaging is driven by either of two fundamental mechanisms: spin echoes or gradient echoes. This lecture introduces the basic concepts and properties of gradient echo formation in comparison to spin-echo imaging. The influence of acquisition parameters on the produced contrast is described and typical artifacts are discussed. Special focus is on the design of rapid gradient-echo sequences based on the principle of steady-state free precession (SSFP), including three main classes: radiofrequency-spoiled gradient-echo, nonbalanced SSFP, and balanced SSFP imaging.
16:00		Forming Echoes with RF Pulses View the Presentation Jakob Assländer Any sequence of radio frequency (RF) pulse forms echoes, such as spin echoes or stimulated echoes. This lecture will cover the underlying principles of such echoes. I will discuss why and when echoes occur, provide an understanding of how “to generate, recognize, use or avoid them,” to use Juergen Hennig’s words. To this end, I will explain two helpful and mutually related tools to simulate echoes: Bloch simulations and the extended phase graph formalism. Last, but not least, I will give some practical examples of how echoes are used in routine MR imaging.
	Contrast Generation
16:30		Magnetization Preparation: How to Generate Contrast View the Presentation Martina Callaghan
17:00		Interactive Session