High-field magnetic resonance imaging of brain iron in Alzheimer disease.
OBJECTIVE
Increased iron deposition in the brain may occur in several neurodegenerative diseases, including Alzheimer disease (AD). Iron deposits shorten T2 relaxation times on T2-weighted magnetic resonance (MR) images. Iron-dependent contrast increases with magnetic field strength. We hypothesized that T2 mapping using 3 T MR imaging (MRI) can disclose differences between normal controls and AD subjects.


METHODS
High-resolution brain imaging protocols were developed and applied to 24 AD patients and 20 age-matched controls using 3 T MRI. Eight anatomical regions of interest were manually segmented, and T2 histograms were computed. A visual analysis technique, the heat map, was modified and applied to the large image data sets generated by these protocols.


RESULTS
A large number (163) of features from these histograms were examined, and 38 of these were significantly different (P < 0.05) between the groups. In the hippocampus, evidence was found for AD-related increases in iron deposition (shortened T2) and in the concentration of free tissue water (lengthened T2). Imaging of a section of postmortem brain before and after chemically extracting the iron established the presence of MRI-detectable iron in the hippocampus, cortex, and white matter in addition to brain regions traditionally viewed as containing high iron concentrations.
Schenck
John F
JF
General Electric Global Research Center, Schenectady, NY 12309, USA. schenck@research.ge.com
Zimmerman
Earl A
EA
Li
Zhu
Z
Adak
Sudeshna
S
Saha
Angshuman
A
Tandon
Reeti
R
Fish
Kenneth M
KM
Belden
Clifford
C
Gillen
Robert W
RW
Barba
Anne
A
Henderson
David L
DL
Neil
William
W
O'Keefe
Timothy
T
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007501:Iron / Q000378:metabolism*; D019189:Iron Metabolism Disorders / Q000175:diagnosis / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male
D015415:Biomarkers; D007501:Iron