Transverse relaxation time reflects brain amyloidosis in young APP/PS1 transgenic mice.

Amyloid deposits are one of the hallmarks of Alzheimer's disease (AD), one of the most devastating neurodegenerative disorders. In transgenic mice modeling Alzheimer's pathology, the MR transverse relaxation time (T2) has been described to be modulated by amyloidosis. This modification has been attributed to the age-related iron deposition that occurs within the amyloid plaques of old animals. In the present study, young APP/PS1 transgenic mice without histochemically detectable iron in the brain were specifically studied. In vivo measurements of T2 in the hippocampus, at the level of the subiculum, were shown to reflect the density of amyloid plaques. This suggests that T2 variations can be induced solely by aggregated amyloid deposits in the absence of associated histologically-detectable iron. Thus T2 from regions with high amyloid load, such as the subiculum, is particularly well suited for following plaque deposition in young animals, i.e., at the earliest stages of the pathological process. Magn Reson Med 58:179–184, 2007. © 2007 Wiley-Liss, Inc.