title: The effect of iron in MRI and transverse relaxation of amyloid-beta plaques in Alzheimer's disease.
abstract: Dysregulation of neural iron is known to occur during the progression of Alzheimer's disease. The visualization of amyloid-beta (Aβ) plaques with MRI has largely been credited to rapid proton relaxation in the vicinity of plaques as a result of focal iron deposition. The goal of this work was to determine the relationship between local relaxation and related focal iron content associated with Aβ plaques. Alzheimer's disease (n=5) and control tissue (n=3) sample slices from the entorhinal cortex were treated overnight with the iron chelator deferoxamine or saline, and microscopic gradient-echo MRI datasets were taken. Subsequent to imaging, the same slices were stained for Aβ and iron, and then compared with regard to parametric R2 * relaxation maps and gradient-echo-weighted MR images. Aβ plaques in both chelated and unchelated tissue generated MR hypo-intensities and showed relaxation rates significantly greater than the surrounding tissue. The transverse relaxation rate associated with amyloid plaques was determined not to be solely a result of iron load, as much of the relaxation associated with Aβ plaques remained following iron chelation. The data indicate a dual relaxation mechanism associated with Aβ plaques, such that iron and plaque composition synergistically produce transverse relaxation.
authors.affiliation: Department of Neurosurgery, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA; Department of Radiology (Center for NMR Research), Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Meadowcroft
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Peters
authors.forename: Rahul P
authors.initials: RP
authors.lastname: Dewal
authors.forename: James R
authors.initials: JR
authors.lastname: Connor
authors.forename: Qing X
authors.initials: QX
authors.lastname: Yang
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D016022:Case-Control Studies; D003676:Deferoxamine / Q000494:pharmacology; D006801:Humans; D007501:Iron / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging; D058225:Plaque, Amyloid / Q000378:metabolism* / Q000473:pathology
chemical_list: D007501:Iron; D003676:Deferoxamine
keywords: Alzheimer's disease; Aβ; MRI; amyloid-beta; chelation; deferoxamine; iron; plaques