| Autor: |
Priovoulos N; School for Mental Health and Neuroscience, Alzheimer Center Limburg, Faculty of Health, Medicine and Life Science, Maastricht University, Maastricht, Netherlands. nikos.priovoulos@maastrichtuniversity.nl., van Boxel SCJ; School for Mental Health and Neuroscience, Alzheimer Center Limburg, Faculty of Health, Medicine and Life Science, Maastricht University, Maastricht, Netherlands., Jacobs HIL; School for Mental Health and Neuroscience, Alzheimer Center Limburg, Faculty of Health, Medicine and Life Science, Maastricht University, Maastricht, Netherlands.; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands.; Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA., Poser BA; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands., Uludag K; Center for Neuroscience Imaging Research, Institute for Basic Science and Department of Biomedical Engineering, Sungkyunkwan University, Seobu-ro 2066, Jangan-gu, Suwon, Republic of Korea.; Techna Institute and Koerner Scientist in MR Imaging, University Health Network, 121-100 College Street, Toronto, M5G 1L5, Canada., Verhey FRJ; School for Mental Health and Neuroscience, Alzheimer Center Limburg, Faculty of Health, Medicine and Life Science, Maastricht University, Maastricht, Netherlands., Ivanov D; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands. dimo.ivanov@maastrichtuniversity.nl. |
| Abstrakt: |
The Locus Coeruleus (LC) and the Substantia Nigra (SN) are small brainstem nuclei that change with aging and may be involved in the development of various neurodegenerative and psychiatric diseases. Magnetization Transfer (MT) MRI has been shown to facilitate LC and the SN visualization, and the observed contrast is assumed to be related to neuromelanin accumulation. Imaging these nuclei may have predictive value for the progression of various diseases, but interpretation of previous studies is hindered by the fact that the precise biological source of the contrast remains unclear, though several hypotheses have been put forward. To inform clinical studies on the possible biological interpretation of the LC- and SN contrast, we examined an agar-based phantom containing samples of natural Sepia melanin and synthetic Cys-Dopa-Melanin and compared this to the in vivo human LC and SN. T 1 and T 2 * maps, MT spectra and relaxation times of the phantom, the LC and the SN were measured, and a two-pool MT model was fitted. Additionally, Bloch simulations and a transient MT experiment were conducted to confirm the findings. Overall, our results indicate that Neuromelanin-MRI contrast in the LC likely results from a lower macromolecular fraction, thus facilitating interpretation of results in clinical populations. We further demonstrate that in older individuals T 1 lengthening occurs in the LC. |
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