Alzheimer Center Limburg, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands.
Alzheimer Center Limburg, School for Mental Health and Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands; Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands; Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital/Harvard Medical School, Boston, MA, USA.
Neuroimage. 2018 Mar;168:427-436. doi: 10.1016/j.neuroimage.2017.07.045. Epub 2017 Jul 22.
Locus Coeruleus (LC) is a neuromelanin-rich brainstem structure that is the source of noradrenaline in the cortex and is thought to modulate attention and memory. LC imaging in vivo is commonly performed with a 2D T-weighted Turbo Spin Echo (TSE) MRI sequence, an approach that suffers from several drawbacks at 3T, including long acquisition times and highly anisotropic spatial resolution. In this study, we developed a high-resolution Magnetization Transfer (MT) sequence for LC imaging at both 7T and 3T and compared its performance to a TSE sequence. Results indicate that LC imaging can be achieved with an MT sequence at both 7 and 3T at higher spatial resolution than the 3T TSE. Furthermore, we investigated whether the currently disputed source of contrast in the LC region with a TSE sequence relates to MT effects or shortened T and T* due to increased iron concentration. Our results suggest that the contrast in the LC area relates to MT effects. To conclude, in this study we managed to image the LC, for the first time, at 7T and at an increased resolution compared to the current state-of-the-art. Imaging the LC is highly relevant for clinical diagnostics as structural tissue properties of the LC may hold promise as a biomarker in neurodegenerative diseases.
蓝斑（LC）是富含神经黑色素的脑干结构，是大脑皮质去甲肾上腺素的来源，被认为可以调节注意力和记忆。LC 的体内成像通常使用二维 T 加权 Turbo Spin Echo（TSE）MRI 序列进行，这种方法在 3T 下存在几个缺点，包括采集时间长和各向异性空间分辨率高。在这项研究中，我们开发了一种用于在 7T 和 3T 下进行 LC 成像的高分辨率磁化转移（MT）序列，并将其性能与 TSE 序列进行了比较。结果表明，与 3T TSE 相比，MT 序列可以在 7T 和 3T 下以更高的空间分辨率实现 LC 成像。此外，我们还研究了 TSE 序列中 LC 区域目前存在争议的对比源是否与 MT 效应或由于铁浓度增加而导致的 T 和 T*缩短有关。我们的结果表明，LC 区域的对比与 MT 效应有关。总之，在这项研究中，我们首次成功地在 7T 下以高于当前最先进水平的分辨率对 LC 进行成像。LC 的成像对于临床诊断非常重要，因为 LC 的结构组织特性可能有望成为神经退行性疾病的生物标志物。
