ISMRM24 - Surprising Aspects of MRI Physics: How To Manage Without Gradients for Spatial Encoding

Surprising Aspects of MRI Physics: How To Manage Without Gradients for Spatial Encoding

Sunrise Course

ORGANIZERS: Brian Hargreaves, Shaoying Huang, Rita Schmidt, Rolf Schulte, Andrew Webb, Ramesh Venkatesan

Tuesday, 07 May 2024

Summit 2

07:00 - 08:00

Moderators: Anke Henning & Christoph Juchem

Skill Level: Intermediate to Advanced

Session Number: S-T-02

CME Credit

Session Number: S-T-02

Overview
In this sunrise session, we want to get a glimpse of some of the surprising and unexpected aspects of MR physics, to motivate thinking out of the box – for example, how one can look in the MRI room, pick up an existing tool and use it for an unconventional purpose; or how we can get an image without having gradients; or even how we can use Eddy currents and Lorenz force for our advantage. Finally, we will deepen our understanding of sequences in our daily use and bring up some of the special aspects of steady state and spin echo acquisitions.

Target Audience
scientists, engineers

Educational Objectives
As a result of attending this course, participants should be able to:
- Explain MR physics;
- Describe how to use RF coils as respiratory and motion sensor and use coils sensitivities for B0 mapping;
- Identify how to get an image without gradients;
- Identify what contrast one can get using Eddy currents and Lorentz force for imaging;
- Describe how one can use a feature of a steady state acquisition that usually results in an artifact to a sensitive approach for fMRI contrast; and
- Examine special cases of spin echo acquisition.

07:00		Spatial Encoding with RF Pulses View Presentation Video Sai Abitha Srinivas Keywords: Physics & Engineering: Pulse design, Physics & Engineering: Physics, Image acquisition: Sequences Traditional MRI spatial encoding relies on bulky, expensive B0 based gradient systems. This lecture explores RF-based encoding as a promising alternative. We'll examine techniques like RFI, TrASE, FrEE, and Bloch-Siegert based encoding, analyzing their advantages and limitations from both hardware and pulse sequence design perspectives.
07:30		Spatial Encoding with Non-Linear Gradients View Presentation Video Sebastian Littin A constant variation of the spatial encoding magnetic fields (SEMs) is usually generated by MRI gradient coils. Due to this constant first spatial derivative, the term „gradients“ is usually used. The main benefit is a direct correlation between image and frequency space. However, other field shapes may be used and can exhibit surprising aspects for slice selection and image encoding.