ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Weekend Educational Course: Magnetic Susceptibility Imaging

Skill Level: Basic to Intermediate

Organizers: Chunlei Liu, Ph.D. & Peter van Zijl, Ph.D.

Sunday 08 May 2016

After presentations of some basic background principles in diamagnetism and paramagnetism, it will be discussed how the local magnetic field in tissue is affected by the tissue composition and neighboring tissues. It will be shown that while MRI signal phase and frequency depend on the position of the organ in the magnetic field, the magnetic susceptibility of tissue can be quantified without such contributions and thus has the potential to be used as a tissue biomarker.

Target Audience
Scientists and clinicians interested in imaging magnetic susceptibility as a quantitative parameter for assessing normal and diseased tissue.

Educational Objectives
Upon completion of this course, participants should be able to:

  • Describe what magnetic susceptibility is;
  • Describe the relationship between signal phase, frequency and susceptibility; and
  • Interpret the possible origins of tissue susceptibiity changes.

Moderators: Chunlei Liu, Peter van Zijl
Susceptibility Properties of Tissue
Jürgen R. Reichenbach1
1Medical Physics Group / IDIR, University Hospital Jena, Jena, Germany
To review some basic material on magnetic susceptibility in materials and biological tissues

Susceptibility Weighted Imaging (SWI)
Karin Shmueli1
1University College London
Susceptibility Weighted Images are produced by multiplying T2*-weighted gradient-echo magnitude and filtered phase images to give a distinctive tissue contrast that highlights tissue magnetic susceptibility variations including those due to haemorrhages, iron deposition and calcifications. SWI has become a widespread clinical tool, particularly for vascular pathologies and neuroimaging with musculoskeletal, cancer and other applications emerging. SWI is qualitative, suffering from the orientation-dependent and non-local nature of phase contrast and cannot help to distinguish between positive and negative susceptibilities. Quantitative Susceptibility Mapping (QSM) overcomes these disadvantages and can even be combined with magnitude images to give a single susceptibility-sensitive image.

Quantitative Susceptibility Mapping (QSM) Basics
Richard Bowtell1
1Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom
Quantitative susceptibility mapping allows the generation of three-dimensional maps showing the variation of the relative magnetic susceptibility within the human body. A number of processing steps are needed to produce susceptibility maps: to convert the wrapped phase measurements into a map of the field variation inside the region of interest; to separate the field perturbation generated by tissue in the region of interest from that produced by external sources; to calculate the susceptibility map from the field perturbation.  Each step will be described here, along with a brief discussion of the relationship between susceptibility and magnetic field perturbation.

Break & Meet the Teachers
Translation of QSM to the Clinic - Fast Single Orientation Methods
Ferdinand Schweser1
1Department of Neurology, University at Buffalo, The State University of New York, Buffalo, NY, United States
In this lecture, we will take a look at recent progress toward fast data acquisition and susceptibility map reconstruction that will ultimately set the foundation for a successful translation of QSM to the clinic.

Iron & Susceptibility in Young & Old Brains
Stefan Ropele1
1Department of Neurology, Medical University of Graz, Graz, Austria
The brain is a unique organ with respect to its non-uniformity of iron distribution, both regionally and cellularly, and because of its iron accumulation pattern across the life span. MRI allows to non-invasively map the iron content and therefore provides a window into age and disease dependent mechanisms that are poorly understood. This presentation will give an overview on the most relevant iron compounds in the brain, their magnetic properties, and their cellular distribution. Additionally, susceptibility related MRI methods for iron mapping will be presented and their limitations will be discussed.

Tissue Anisotropy Origin (Brain, Heart, Muscle)
Jongho Lee1
1Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of
In this educational presentation, the origins of magnetic susceptibility induced signal anisotropy will be discussed. The observations of magnitude and phase signal anisotropy in gradient echo have been reported in the brain, heart, muscle and kidney. I will explain the sources (e.g. microstructural anisotropy and susceptibility anisotropy) for the observed signal anisotropy. Potential applications of the signal anisotropy will be discussed.

Break & Meet the Teachers
Tissue Anisotropy Mapping
Xu Li1,2
1Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F.M.Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
Many recent studies have found out that macroscopic magnetic susceptibility at the scale of a MR imaging voxel is anisotropic in tissues with ordered microstructure such as white matter fibers. This lecture reviews some of such experimental evidences and introduces methods to map such tissue anisotropy. First, we go over the theory, acquisition and processing methods of susceptibility tensor imaging (STI) which uses MR phase measurements collected at different sample orientations with respect to the main field. We then review some other mapping methods using susceptibility related MR measures that are orientation dependent such as R2* and frequency difference.

Susceptibility MRI Outside the Brain
Diego Hernando1
1University of Wisconsin-Madison, WI, United States
There is growing research interest in the development of QSM techniques for extra-cranial applications. These techniques are faced with additional challenges beyond those typically encountered in brain QSM. By addressing important challenges such as the presence of motion, fat, and large susceptibility shifts, these techniques may enable novel QSM applications for research and clinical applications in multiple organs, including heart, liver, kidney, pancreas, breast as well as whole-body applications. 

Pediatric QSM
Deqiang Qiu1
1Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States
Adjournment & Meet the Teachers

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.