Contrast Mechanisms Associated With Neuromelanin-MRI
Contrast Mechanisms Associated With Neuromelanin-MRI
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DOI：
10.1002/mrm.26584
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发表时间：
2017-11-01
影响因子：
3.3
通讯作者：
Costa, Antonella
中科院分区：
文献类型：
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作者：
Trujillo, Paula;Summers, Paul E.;Costa, Antonella
目的：探讨与对比度在neuromilinMRIMRI.Methods：具有不同浓度的合成黑色素与不同程度的铁负载的黑色素在3特斯拉扫描仪上使用弛豫和定量磁化transfer（MT）检查的物理机制。结果：浓度依赖性T-1和T-2缩短是最明显的黑色素与铁结合时。无金属黑色素的磁化转移光谱的影响可以忽略不计。相反，铁负载黑色素的存在下，导致磁化传递率降低。黑色素或铁（或两者）的存在下，没有显着的大分子含量的影响，由池大小ratio.Conclusion：在神经黑色素-MRI的对比度的主要机制似乎是T-1减少与黑色素-铁复合物。大分子含量不受黑色素存在或不存在铁的显著影响，因此MT不受直接影响。然而，由于T-1在确定MT加权信号中起作用，因此在黑色素-铁络合物的存在下磁化传递率降低。(C)2016年国际医学磁共振学会。
Purpose: To investigate the physical mechanisms associated with the contrast observed in neuromelanin MRI.Methods: Phantoms having different concentrations of synthetic melanins with different degrees of iron loading were examined on a 3 Tesla scanner using relaxometry and quantitative magnetization transfer (MT).Results: Concentration-dependent T-1 and T-2 shortening was most pronounced for the melanin pigment when combined with iron. Metal-free melanin had a negligible effect on the magnetization transfer spectra. On the contrary, the presence of iron-laden melanins resulted in a decreased magnetization transfer ratio. The presence of melanin or iron (or both) did not have a significant effect on the macromolecular content, represented by the pool size ratio.Conclusion: The primary mechanism underlying contrast in neuromelanin-MRI appears to be the T-1 reduction associated with melanin-iron complexes. The macromolecular content is not significantly influenced by the presence of melanin with or without iron, and thus the MT is not directly affected. However, as T-1 plays a role in determining the MT-weighted signal, the magnetization transfer ratio is reduced in the presence of melanin-iron complexes. (C) 2016 International Society for Magnetic Resonance in Medicine.