Quantification of punctate iron sources using magnetic resonance phase.
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.
McAuley
Grant
G
Neurosurgery Center for Research, Training and Education, Loma Linda University, Loma Linda, California 92354, USA.
Schrag
Matthew
M
Sipos
Pál
P
Sun
Shu-Wei
SW
Obenaus
Andre
A
Neelavalli
Jaladhar
J
Haacke
E Mark
EM
Holshouser
Barbara
B
Madácsi
Ramóna
R
Kirsch
Wolff
W
D000465:Algorithms; D002543:Cerebral Hemorrhage / Q000175:diagnosis* / Q000378:metabolism*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007501:Iron / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D007501:Iron