Longitudinal assessment of Alzheimer's beta-amyloid plaque development in transgenic mice monitored by in vivo magnetic resonance microimaging

PURPOSE: To assess the development of beta-amyloid (Abeta) plaques in the brain with age in the transgenic mouse model of Alzheimer's disease (AD) pathology by in vivo magnetic resonance microimaging (microMRI). MATERIALS AND METHODS: Live transgenic mice (Tg2576) and nontransgenic littermates (control) were studied at regular intervals between the ages of 12 and 18 months. Plaques were visualized using a T(2)-weighted rapid acquisition with relaxation enhancement (RARE) sequence. Changes in T(2) relaxation times were followed using a multislice multiecho (MSME) sequence. Plaque load and numerical density in MR images were calculated using SCIL image software. RESULTS: Abeta plaques were clearly detected with the T(2)-weighted RARE sequence in the hippocampal and cortical regions of the brain of Tg2576 mice but not in control mice. Following the plaque development in the same animals with age showed that plaque area, number, and size increased markedly, while T(2) relaxation time showed a decreasing trend with age. CONCLUSION: These results demonstrate that microMRI is a viable method for following the development of Abeta plaques in vivo, and suggest that this method may be feasible for assessing the effect of therapeutic interventions over time in the same animals.