Quantitative Susceptibility Mapping in the Human Brain

Quantitative Susceptibility Mapping in the Human Brain
Author: Diana Khabipova
Publisher:
Total Pages: 193
Release: 2016
Genre:
ISBN:

Mots-clés de l'autrice: MRI ; magnetic resonance imaging ; QSM ; quantitative susceptibility mapping ; apparent transversal relaxation rate ; longitudinal relaxation rate ; transversal relaxation rate ; human brain.

Quantitative Magnetic Resonance Imaging

Quantitative Magnetic Resonance Imaging
Author: Nicole Seiberlich
Publisher: Academic Press
Total Pages: 1094
Release: 2020-11-18
Genre: Computers
ISBN: 0128170581

Quantitative Magnetic Resonance Imaging is a ‘go-to’ reference for methods and applications of quantitative magnetic resonance imaging, with specific sections on Relaxometry, Perfusion, and Diffusion. Each section will start with an explanation of the basic techniques for mapping the tissue property in question, including a description of the challenges that arise when using these basic approaches. For properties which can be measured in multiple ways, each of these basic methods will be described in separate chapters. Following the basics, a chapter in each section presents more advanced and recently proposed techniques for quantitative tissue property mapping, with a concluding chapter on clinical applications. The reader will learn: The basic physics behind tissue property mapping How to implement basic pulse sequences for the quantitative measurement of tissue properties The strengths and limitations to the basic and more rapid methods for mapping the magnetic relaxation properties T1, T2, and T2* The pros and cons for different approaches to mapping perfusion The methods of Diffusion-weighted imaging and how this approach can be used to generate diffusion tensor maps and more complex representations of diffusion How flow, magneto-electric tissue property, fat fraction, exchange, elastography, and temperature mapping are performed How fast imaging approaches including parallel imaging, compressed sensing, and Magnetic Resonance Fingerprinting can be used to accelerate or improve tissue property mapping schemes How tissue property mapping is used clinically in different organs Structured to cater for MRI researchers and graduate students with a wide variety of backgrounds Explains basic methods for quantitatively measuring tissue properties with MRI - including T1, T2, perfusion, diffusion, fat and iron fraction, elastography, flow, susceptibility - enabling the implementation of pulse sequences to perform measurements Shows the limitations of the techniques and explains the challenges to the clinical adoption of these traditional methods, presenting the latest research in rapid quantitative imaging which has the possibility to tackle these challenges Each section contains a chapter explaining the basics of novel ideas for quantitative mapping, such as compressed sensing and Magnetic Resonance Fingerprinting-based approaches

High Field Brain MRI

High Field Brain MRI
Author: Tommaso Scarabino
Publisher: Springer
Total Pages: 385
Release: 2017-02-27
Genre: Medical
ISBN: 3319441744

This book describes the development of systems of magnetic resonance imaging using the higher magnetic field strength of 3 tesla, in comparison to the current gold standard of 1.5 tesla. These new systems of MRI make it possible to perform with high spatial, temporal and contrast resolution not only morphological examinations but also functional studies on spectroscopy, diffusion, perfusion, and cortical activation, thus helping research and providing an important tool for routine diagnostic activity. At the same time the new systems offer unparalleled sensitivity and specificity in the numerous conditions of neuroradiological interest.

Magnetic Resonance Brain Imaging

Magnetic Resonance Brain Imaging
Author: Jörg Polzehl
Publisher: Springer Nature
Total Pages: 268
Release: 2023-11-12
Genre: Medical
ISBN: 3031389492

This book discusses modelling and analysis of Magnetic Resonance Imaging (MRI) data of the human brain. For the data processing pipelines we rely on R, the software environment for statistical computing and graphics. The book is intended for readers from two communities: Statisticians, who are interested in neuroimaging and look for an introduction to the acquired data and typical scientific problems in the field and neuroimaging students, who want to learn about the statistical modeling and analysis of MRI data. Being a practical introduction, the book focuses on those problems in data analysis for which implementations within R are available. By providing full worked-out examples the book thus serves as a tutorial for MRI analysis with R, from which the reader can derive its own data processing scripts. The book starts with a short introduction into MRI. The next chapter considers the process of reading and writing common neuroimaging data formats to and from the R session. The main chapters then cover four common MR imaging modalities and their data modeling and analysis problems: functional MRI, diffusion MRI, Multi-Parameter Mapping and Inversion Recovery MRI. The book concludes with extended Appendices on details of the utilize non-parametric statistics and on resources for R and MRI data. The book also addresses the issues of reproducibility and topics like data organization and description, open data and open science. It completely relies on a dynamic report generation with knitr: The books R-code and intermediate results are available for reproducibility of the examples.

Efficient Whole-brain Orientation-specific T1 Mapping at 3 Tesla

Efficient Whole-brain Orientation-specific T1 Mapping at 3 Tesla
Author: Daniel Andrews
Publisher:
Total Pages:
Release: 2019
Genre:
ISBN:

"Quantitative magnetic resonance imaging (qMRI) techniques such as T1 mapping are used to probe the microstructure of white matter in the human brain. However, these methods cannot disentangle the unique microstructural features of different white matter fibre populations, also called tracts, inside the voxel. This is a significant problem for qMRI because 60 to 90 % of MR image voxels in white matter contain complex configurations of multiple fibres. This calls for new qMRI methods that can disentangle the microstructure of individual tracts in a voxel. A recent MRI method combines inversion recovery (IR) and diffusion-weighted imaging (DWI) to measure tract-specific T1 relaxation times inside the voxel. In human brain white matter, T1 is sensitive to tract myelination, and DWI is sensitive to tract geometry. IR-DWI was used at 7 tesla (T) to resolve multiple diffusion orientation-specific T1 values in phantoms (test objects) and in healthy human subjects. This original implementation is limited, however, by a long scan time, requiring over two hours for a whole-brain acquisition. An accelerated IR-DWI method applicable in more common 3 T MRI systems was developed in this thesis work at the McConnell Brain Imaging Centre of McGill University in collaboration with researchers at the Athinoula A. Martinos Center for Biomedical Imaging in Charlestown, Massachusetts, USA. Accelerated IR-DWI combines a slice-shuffled readout and simultaneous multi-slice imaging to enable whole-brain scanning in under 15 minutes. Accelerated IR-DWI was used to extract multiple orientation-specific T1 values in voxels with crossing fibres in a phantom and in the healthy human brain. This thesis demonstrates the feasibility of accelerated IR-DWI at 3 T and validates the technique. Future studies will use accelerated IR-DWI to examine how altered myelination in specific tracts affects structural connectivity in the brain and, ultimately, behaviour"--

Quantitative MRI of the Brain

Quantitative MRI of the Brain
Author: Paul Tofts
Publisher: John Wiley & Sons
Total Pages: 678
Release: 2003
Genre: Medical
ISBN: 9780470847213

A 'how to' manual of quantitative MR, essential for anyone who wants to use the gamut of modern quantitative methods to measure the effects of neurological diseases, its progression and its response to treatment. It is also designed for research-minded radiologists, neurologists and MRI physicists who are considering undertaking quantitative work, as well as those already in the field.

Susceptibility Effects in Ultra-high Field Magnetic Resonance Imaging of the Human Brain

Susceptibility Effects in Ultra-high Field Magnetic Resonance Imaging of the Human Brain
Author: Trong-Kha Truong
Publisher:
Total Pages:
Release: 2004
Genre: Brain
ISBN:

Abstract: In magnetic resonance imaging (MRI), susceptibility differences between deoxygenated blood or iron and surrounding tissue induce mesoscopic static magnetic field (B0) inhomogeneities that provide a valuable contrast mechanism for imaging of the vasculature, functional MRI, and assessment of iron content. On the other hand, susceptibility differences at air/tissue interfaces induce macroscopic B0 inhomogeneities resulting in image artifacts. Ultra-high field (greater than or equal to 7 tesla) MRI benefits from an enhanced susceptibility contrast, but also suffers from more severe susceptibility artifacts. The development of methods to reduce such artifacts while maintaining susceptibility contrast is the objective of this research. Development of susceptibility artifact correction methods requires knowledge of the macroscopic susceptibility effects, which can be quantified by mapping B0, whereas optimization of methods sensitive to susceptibility contrast requires understanding of the mesoscopic susceptibility effects, which can be characterized by relaxation time measurements. We first developed various methods for B0 numerical simulations and experimental mapping. Our simulations showed that air/tissue interfaces at the shoulders induce substantial B0 inhomogeneities in the brain, and that tilting the head backwards can significantly reduce some of these inhomogeneities. We used the B0 simulations and experimental mapping as well as radiofrequency magnetic field (B1) mapping to correlate the B0 and B1 inhomogeneity with the artifacts observed on images of the human brain acquired at 8 T. We then evaluated different susceptibility artifact correction methods at ultra-high field strength using B0 maps, including passive shimming, post-processing, and gradient compensation, and found the latter to be the most effective. Finally, we developed various methods for T2 and T2* relaxation time measurements at ultra-high field strength that are faster and less sensitive to B0 and/or B1 inhomogeneity than existing methods, and demonstrated these advantages in phantom and human studies. New findings obtained in this work will be used to improve ultra-high field MRI of the human brain, particularly for imaging of the venous microvasculature and assessment of iron content.