Susceptibility weighted imaging (SWI)

Susceptibility differences between tissues can be utilized as a new type of contrast in MRI that is different from spin density, T1‐, or T2‐weighted imaging. Signals from substances with different magnetic susceptibilities compared to their neighboring tissue will become out of phase with these tiss...

Full description

Saved in:
Bibliographic Details
Published in:Magnetic resonance in medicine 2004-09, Vol.52 (3), p.612-618
Main Authors: Haacke, E. Mark, Xu, Yingbiao, Cheng, Yu-Chung N., Reichenbach, Jürgen R.
Format: Article
Language:English
Subjects:
artery/vein separation
Body Water - metabolism
Brain - anatomy & histology
Brain - metabolism
Cerebrovascular Circulation
Humans
imaging iron
Iron - metabolism
Lipid Metabolism
Magnetic Resonance Imaging - methods
magnetic susceptibility
phase imaging
water/fat separation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Susceptibility differences between tissues can be utilized as a new type of contrast in MRI that is different from spin density, T1‐, or T2‐weighted imaging. Signals from substances with different magnetic susceptibilities compared to their neighboring tissue will become out of phase with these tissues at sufficiently long echo times (TEs). Thus, phase imaging offers a means of enhancing contrast in MRI. Specifically, the phase images themselves can provide excellent contrast between gray matter (GM) and white matter (WM), iron‐laden tissues, venous blood vessels, and other tissues with susceptibilities that are different from the background tissue. Also, for the first time, projection phase images are shown to demonstrate tissue (vessel) continuity. In this work, the best approach for combining magnitude and phase images is discussed. The phase images are high‐pass‐filtered and then transformed to a special phase mask that varies in amplitude between zero and unity. This mask is multiplied a few times into the original magnitude image to create enhanced contrast between tissues with different susceptibilities. For this reason, this method is referred to as susceptibility‐weighted imaging (SWI). Mathematical arguments are presented to determine the number of phase mask multiplications that should take place. Examples are given for enhancing GM/WM contrast and water/fat contrast, identifying brain iron, and visualizing veins in the brain. Magn Reson Med 52:612–618, 2004. © 2004 Wiley‐Liss, Inc.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.20198