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Quantification of punctate iron sources using magnetic resonance phase
Author(s) -
McAuley Grant,
Schrag Matthew,
Sipos Pál,
Sun ShuWei,
Obenaus Andre,
Neelavalli Jaladhar,
Haacke E. Mark,
Holshouser Barbara,
Madácsi Ramóna,
Kirsch Wolff
Publication year - 2010
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22185
Subject(s) - hemosiderin , quantitative susceptibility mapping , magnetic resonance imaging , nuclear magnetic resonance , phase (matter) , susceptibility weighted imaging , content (measure theory) , brain tissue , white matter , materials science , biomedical engineering , chemistry , pathology , radiology , medicine , physics , mathematics , mathematical analysis , organic chemistry
Iron‐mediated tissue damage is present in cerebrovascular and neurodegenerative diseases and neurotrauma. Brain microbleeds are often present in these maladies and are assuming increasing clinical importance. Because brain microbleeds present a source of pathologic iron to the brain, the noninvasive quantification of this iron pool is potentially valuable. Past efforts to quantify brain iron have focused on content estimation within distributed brain regions. In addition, conventional approaches using “magnitude” images have met significant limitations. In this study, a technique is presented to quantify the iron content of punctate samples using phase images. Samples are modeled as magnetic dipoles and phase shifts due to local dipole field perturbations are mathematically related to sample iron content and radius using easily recognized geometric features in phase images. Phantoms containing samples of a chitosan‐ferric oxyhydroxide composite (which serves as a mimic for hemosiderin) were scanned with a susceptibility‐weighted imaging sequence at 11.7 T. Plots relating sample iron content and radius to phase image features were compared to theoretical predictions. The primary result is the validation of the technique by the excellent agreement between theory and the iron content plot. This research is a potential first step toward quantification of punctate brain iron sources such as brain microbleeds. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.