ISSN# 1545-4428 | Published date: 19 April, 2024
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At-A-Glance Session Detail
   
MR Contrasts Across Field Strengths: When Is Less More?
Weekend Course
ORGANIZERS: Jessica Bastiaansen, Henrik Odéen, Marco Palombo, Simon Robinson
Sunday, 05 May 2024
Room 331-332
07:45 -  11:35
Moderators: Ahsan Javed & Nicole Seiberlich
Skill Level: Basic to Advanced
Session Number: WE-23
CME Credit

Session Number: WE-23

Overview
This educational session explores the contrasts and capabilities of MRI at various field strengths, ranging from low field (e.g., 0.55-T) to ultra-high field (e.g., 7+T). The session aims to provide insights into the advantages and limitations of MRI at different field strengths.

Target Audience
This session is designed for researchers interested in gaining a comprehensive understanding of MRI contrasts across field strengths. The content caters to both novice and experienced MRI practitioners.

Educational Objectives
As a result of attending this course, participants should be able to:
- Identify the fundamental contrast mechanisms in MRI at low and ultra-low field strengths (0.55-T) and their applications;
- Examine the physical principles and imaging capabilities of MRI at high and ultra-high field strengths (7+T) with a focus on susceptibility effects and advanced techniques;
- Evaluate diffusion and perfusion imaging across different field strengths, including methods, physical aspects, and clinical relevance;
- Assess the advantages and opportunities of lower sensitivity to susceptibility effects at low field strengths, particularly in applications such as imaging implants and lung tissue;
- Discover the unique clinical applications of MRI at lower and higher field strengths, including scenarios where low field excels compared to high field and vice versa; and
- Recognize the potential challenges and opportunities for future research and developments in the field of MRI contrasts across varying magnetic field strengths.

07:45 Introduction to Contrast Mechanisms at Low & Ultra-Low Field
Ed Wu
08:10 Introduction to Contrast Mechanisms at High & Ultra-High Field
Karin Markenroth Bloch

Keywords: Physics & Engineering: High-Field MRI

Changes in relaxation parameters give rise to changed image contrasts at high field strengths (≥7T) as compared to lower field. These changes can benefit certain sequences and create challenges in other situations. The presentation will give an introductory overview of contrast mechanisms at high field (≥7T), including T1, T2, T2*, BOLD, flow, MRSI and multinuclear imaging. In addition, artifacts at higher field that have consequences for image contrast will be discussed.
08:35 Diffusion Across Field Strengths
Mara Cercignani

Keywords: Contrast mechanisms: Diffusion

This lecture will discuss the principles and challenges of diffusion MRI (dMRI) at different field strengths. Low field (<1T) poses signal-to-noise ratio challenges, while high field (>3T) faces issues like field inhomogeneity and shorter T2 relaxation times.  At high field, strategies to minimize SNR loss include non-Cartesian k-space trajectories and 3D sequences. Conversely, at low field, long scan times hinder data quality, necessitating innovative acquisition and image reconstruction techniques. The talk will discuss the attractiveness and challenges of different field strengths and proposes strategies for addressing dMRI difficulties.
09:00Perfusion Across Field Strengths
Danny Wang

Keywords: Contrast mechanisms: Perfusion, Physics & Engineering: High-Field MRI, Physics & Engineering: Low-field MRI

Motivation: Ultrahigh field (UHF>=7T) and high performance low field (HPLF<1T) MR systems have greatly expanded the field strengths and associated applications for perfusion MRI. 

Goal(s): To summarize recent advances of perfusion MRI across field strengths.

Approach: UHF offers dual benefits for ASL with increased SNR and blood T1, and increased sensitivity for dynamic contrast based perfusion MRI. HPLF systems provide improved field homogeneity and prolonged T2* and is ideal for cardio-pulmonary perfusion imaging.

Results: Perfusion MRI across a wide range of field strengths represent specific opportunities and challenges for specific clinical applications to be further exploited in near future. 

Impact: Perfusion MRI across a wide range of field strengths represent specific opportunities and challenges for specific clinical applications to be further exploited in near future.  

09:25 Break & Meet the Teachers
09:55 Susceptibility Effects at Low Field
Zhiyong Zhang

Keywords: Contrast mechanisms: Susceptibility, Physics & Engineering: Low-field MRI

The magnetic susceptibility effects are generally characterized by geometric distortion, very dark and very bright contrast areas. In this talk, the pros and cons of the susceptibility effects at low field are introduced. Several examples of susceptibility-weighted imaging at low field show the contrast features and their clinical challenges. Opportunities of high sensitivity in-vivo contrast agents for low field MRI are discussed. More importantly, the advantages and opportunities of lower sensitivity to susceptibility effects at low field strengths are highlighted, particularly in applications such as imaging implants and lung tissue.
10:20 Susceptibility Imaging at High Field
Pinar Özbay
10:45 Clinical Applications at Lower Field Strengths
Sean Deoni
11:10 Clinical Applications at High & UHF
Siegfried Trattnig

Keywords: Physics & Engineering: High-Field MRI

With the higher-signal to-noise ratio 7T allows improved visualization of cortical lesions, the central vein sign and the detection of paramagnetic rim lesions in MS for differential diagnosis to non-MS lesions and disease progression and small structures in MSK.
High resolution MR spectroscopic imaging at 7T has provided new insights into tumor grading and tumor recurrence, early stages of inflammation and correlation with clinical disability of MS patients.
Multi-nuclear clinical applications such as sodium imaging have shown high potential for definition of responder to neoadjuvant chemotherapy in breast cancer and the evaluation of repair tissue quality after cartilage transplantation.