Abstract Body

Various MRI techniques including diffusion tensor imaging (DTI) and magnetization transfer imaging as well as iron mapping allow to detect changes in tissue microstructure in Alzheimer´s disease. The contribution of these techniques as diagnostic and prognostic tools are widely undetermined. This presentation will display new data on free water imaging, Magnetization Transfer Imaging and Iron Mapping.

Recent advances in diffusion MRI modeling enable more detailed insight into DTI alterations. Of specific interest is the free water (FW) diffusion MRI model. In a large cohort of community-dwelling individuals we show that the FW compartment correlates more closely to cognitive impairment than traditional DTI metrics such as mean diffusivity and fractional aniosptropy. As to whether alterations of the free water compartment can predict conversion of patients to dementia is yet unclear.

The second section of the talk focuses on magnetization transfer imaging and demonstrates that reductions of the magnetization transfer ratio in AD signature areas and in white matter regions of the brain contribute to cognitive impairment of AD patients, independently of brain atrophy.

Finally, longitudinal data on MR-detected iron accumulation in AD will be shown. The finding that iron in the temporal cortex predicts cognitive decline beyond what is determined by development of brain atrophy is novel.

In conclusion, the presentation highlights the potential of various MRI techniques to determine microstructural tissue alterations in the brain of elderly people without and with dementia and indicates that such changes provide clinically relevant information beyond what can be expected from structural MRI.