backdrop

LOW-FIELD MRI

MICCAI 2024 Tutorial

MICCAI Logo

Introduction

An increasingly significant recent trend in MRI research has been aimed towards the democratisation of MRI access in lower- and middle-income countries (LMICs) through low-cost MRI systems. Such systems typically have much lower magnetic field strength than the clinical standard in high-income countries (below 1 T or even 0.1 T compared to 1.5 T or 3 T) for cost and accessibility reasons. As the SNR of MR images increases with field strength, the quality of the images obtained with such systems is inherently limited; however, this has driven the development and optimisation of methods to increase image quality at the acquisition, reconstruction, or post-processing stage.

In summary, the development and utilization of low-field MRI systems, especially in LMICs, presents great challenges but also great potential opportunities and obvious benefits for the population. This tutorial will give an overview of such challenges and of recent technological advancements that could be exploited, and it will highlight the potential contribution of the MICCAI community in the effort towards MRI democratisation.

Aims and relevance to the MICCAI community

This MICCAI tutorial aims to highlight the potential contributions the MICCAI community can make towards efforts to democratize MRI access across the globe. One key part of the effort is the development, deployment, and effective utilization of low-cost MRI systems, particularly to lower- and middle-income countries (LMICs) such as sub-Saharan Africa. Low-cost systems typically sacrifice field strength to favour economy and accessibility, but this entails inherent limitations in image quality that should be taken into account and counteracted to obtain images of sufficient diagnostic value. The MICCAI community’s strengths in image analysis, enhancement, and synthesis perfectly complement the efforts in MR hardware designers and physicists in development and realising the potential of these emerging platforms.

Tutorial speakers will explain the technical challenges of low-field MRI as well as of the practical challenges of deploying MRI in LMICs. We will also give an overview of recent advancements in hardware, acquisition, and post-processing for low-field MRI. Finally, we will have a round table discussing the most critical open problems and how the MICCAI community could contribute.

Background

The current clinical standard for the magnetic field of MRI scanners in high-income countries is 1.5T or 3T and the SNR of the resulting images increases with the magnetic field. However, in most LMICs, due to limited resources and infrastructure issues, only low-field ( less than 1T) MR scanners are available, which is a major limitation for the diagnosis and treatment planning of several diseases.

Furthermore, large parts of the world population, especially in rural areas of Africa and Asia, has no access to MRI systems. To minimise this problem, portable systems have been developed in recent years thanks to advances in MR hardware. However, portable systems typically compromise on magnetic field strength so are ultra-low-field systems (bwelow 0.1T). They also find application in situations where patients are difficult to move or have implants. Therefore, there has recently been growing interest in low-field MRI, despite its inherent limitations. Post-processing techniques, especially based on Artificial Intelligence, have been developed to improve the reconstruction of low-field MR images and their quality in terms of SNR, contrast between tissues and/or spatial resolution.

Learning objectives

Participants will learn about:

  • The differences between MR images at different magnetic fields and the technical challenges with low-field acquisitions
  • The practical challenges in deploying MR systems in LMICs
  • Recent advancements in low-field MR hardware and examples of successfully developed systems
  • Numerical simulation of diffusion process
  • Recent advancements in low-field MR acquisitions
  • AI techniques that can improve the quality of low-field MR images and enhance the accessibility and democratization of MRI


Invited Speakers

Mara Cercignani
Cardiff University, UK
Ed X. Wu
Hong Kong University, HK
Johnes Obungoloch
Mbarara University, Uganda
Rebecca Ramb
Siemens Healthineers, Germany
Juan E. Iglesias
Martinos Centre, USA
Hongxiang Lin
Zhejiang Lab, China

Organisers

Daniel C. Alexander
University College London, UK
Matteo Figini
University College London, UK
Godwin I. Ogbole
College of Medicine University of Ibadan, Nigeria