Betts Matthew J, Acosta-Cabronero Julio, Cardenas-Blanco Arturo, Nestor Peter J, Düzel Emrah
German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.
Neuroimage. 2016 Sep;138:43-63. doi: 10.1016/j.neuroimage.2016.05.024. Epub 2016 May 13.
Quantitative susceptibility mapping (QSM) has recently emerged as a novel magnetic resonance imaging (MRI) method to detect non-haem iron deposition, calcifications, demyelination and vascular lesions in the brain. It has been suggested that QSM is more sensitive than the more conventional quantifiable MRI measure, namely the transverse relaxation rate, R2*. Here, we conducted the first high-resolution, whole-brain, simultaneously acquired, comparative study of the two techniques using 7Tesla MRI. We asked which of the two techniques would be more sensitive to explore global differences in tissue composition in elderly adults relative to young subjects. Both QSM and R2* revealed strong age-related differences in subcortical regions, hippocampus and cortical grey matter, particularly in superior frontal regions, motor/premotor cortices, insula and cerebellar regions. Within the basal ganglia system-but also hippocampus and cerebellar dentate nucleus-, QSM was largely in agreement with R2* with the exception of the globus pallidus. QSM, however, provided superior anatomical contrast and revealed age-related differences in the thalamus and in white matter, which were otherwise largely undetected by R2* measurements. In contrast, in occipital cortex, age-related differences were much greater with R2* compared to QSM. The present study, therefore, demonstrated that in vivo QSM using ultra-high field MRI provides a novel means to characterise age-related differences in the human brain, but also combining QSM and R2* using multi-gradient recalled echo imaging can potentially provide a more complete picture of mineralisation, demyelination and/or vascular alterations in aging and disease.
定量磁化率成像（QSM）最近已成为一种新型的磁共振成像（MRI）方法，用于检测大脑中的非血红素铁沉积、钙化、脱髓鞘和血管病变。有人提出，QSM比更传统的可量化MRI测量方法，即横向弛豫率R2更敏感。在此，我们使用7特斯拉MRI对这两种技术进行了首次高分辨率、全脑、同时采集的对比研究。我们探究了相对于年轻受试者，这两种技术中哪一种对探索老年人组织成分的整体差异更敏感。QSM和R2均显示，在皮质下区域、海马体和皮质灰质中存在与年龄相关的显著差异，尤其是在额上区、运动/运动前皮质、岛叶和小脑区域。在基底神经节系统内——以及海马体和小脑齿状核中——除苍白球外，QSM与R2在很大程度上一致。然而，QSM提供了更好的解剖对比度，并揭示了丘脑和白质中与年龄相关的差异，而这些差异在很大程度上无法通过R2测量检测到。相比之下，在枕叶皮质中，与QSM相比，R2显示的与年龄相关的差异要大得多。因此，本研究表明，使用超高场MRI的活体QSM为表征人类大脑中与年龄相关的差异提供了一种新方法，而且将QSM和R2与多梯度回波成像相结合，可能会更全面地呈现衰老和疾病过程中的矿化、脱髓鞘和/或血管改变情况。
