Overview
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.
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07:55
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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
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08:20
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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.
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08:45
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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.
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09:10
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Break & Meet the Teachers |
09:20
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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.
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09:45
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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.
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10:10
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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.
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10:35
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Break & Meet the Teachers |
10:45
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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.
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11:10
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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.
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11:35
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Pediatric QSM
Deqiang Qiu1
1Radiology and Imaging Sciences, Emory
University, Atlanta, GA, United States
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12:00
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Adjournment & Meet the
Teachers |
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