Gizeaddis Lamesgin Simegn, Yulu Song, Saipavitra Murali-Manohar, Helge J Zöllner, Christopher W Davies-Jenkins, Dunja Simicic, Kathleen E Hupfeld, Aaron T Gudmundson, Emlyn Muska, Emily Carter, Steve C N Hui, Vivek Yedavalli, Georg Oeltzschner, Douglas C Dean, Can Ceritoglu, J Tilak Ratnanather, Eric Porges, Richard Edden
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引用次数: 0
Abstract
Metabolite concentration estimates from magnetic resonance spectroscopy (MRS) are typically quantified using water referencing, correcting for relaxation-time differences between metabolites and water. One common approach is to correct the reference signal for differential relaxation within three tissue compartments (gray matter, white matter, and cerebrospinal fluid) using fixed literature values. However, water relaxation times (T1 and T2) vary between brain locations and with age. MRS studies, even those measuring metabolite levels across the lifespan, often ignore these effects, because of a lack of reference data. The purpose of this study is to develop a water relaxometry atlas and to integrate location- and age-appropriate relaxation values into the MRS analysis workflow. One hundred one volunteers (51 men, 50 women; ~10 male, and 10 female participants per decade from the 20s to 60s) were recruited. T1-weighted MPRAGE images ((1-mm)3 isotropic resolution) were acquired. Whole-brain water T1 and T2 measurements were made with DESPOT ((1.4 mm)3 isotropic resolution) at 3T. T1 and T2 maps were registered to the JHU MNI-SS/EVE atlas using affine and LDDMM transformation. The atlas's 268 parcels were reduced to 130 by combining homologous parcels. Mean T1 and T2 values were calculated for each parcel in each subject. Linear models of T1 and T2 as functions of age were computed, using age - 30 as the predictor. Reference atlases of "age-30-intercept" and age-slope for T1 and T2 were generated. The atlas-based workflow was integrated into Osprey, which co-registers MRS voxels to the atlas and calculates location- and age-appropriate water relaxation parameters for quantification. The water relaxation aging atlas revealed significant regional and tissue differences in water relaxation behavior across adulthood. Using location- and subject-appropriate reference values in the MRS analysis workflow removes a current methodological limitation and is expected to reduce quantification biases associated with water-referenced tissue correction, especially for studies of aging.
磁共振波谱(MRS)的代谢物浓度估计通常使用水参照来量化,纠正代谢物和水之间的松弛时间差异。一种常见的方法是使用固定的文献值来校正三个组织区(灰质、白质和脑脊液)内的微分松弛参考信号。然而,水松弛时间(T1和T2)因大脑位置和年龄而异。由于缺乏参考数据,即使是那些测量整个生命周期中代谢物水平的MRS研究,也经常忽略这些影响。本研究的目的是开发一个水松弛测量图谱,并将适合位置和年龄的松弛值整合到MRS分析工作流程中。101名志愿者(51名男性,50名女性;(男性10名,女性10名,年龄从20岁到60岁)。获得t1加权MPRAGE图像((1-mm)3各向同性分辨率)。在3T时用DESPOT ((1.4 mm)3各向同性分辨率)测量全脑水T1和T2。T1和T2图谱通过仿射和LDDMM变换注册到JHU mini - ss /EVE图谱中。通过合并同源包裹,地图集的268个包裹减少到130个。计算每位受试者每个包裹的平均T1和T2值。以年龄- 30岁为预测因子,计算T1和T2作为年龄函数的线性模型。生成T1和T2的“年龄-30岁截距”和年龄-斜率参考地图集。基于地图集的工作流程集成到Osprey中,它将MRS体素共同注册到地图集中,并计算适合位置和年龄的水松弛参数以进行量化。水松弛老化图谱揭示了成年期水松弛行为的显著区域和组织差异。在MRS分析工作流程中使用位置和受试者合适的参考值消除了当前方法学上的限制,并有望减少与水参考组织校正相关的量化偏差,特别是在衰老研究中。
期刊介绍:
NMR in Biomedicine is a journal devoted to the publication of original full-length papers, rapid communications and review articles describing the development of magnetic resonance spectroscopy or imaging methods or their use to investigate physiological, biochemical, biophysical or medical problems. Topics for submitted papers should be in one of the following general categories: (a) development of methods and instrumentation for MR of biological systems; (b) studies of normal or diseased organs, tissues or cells; (c) diagnosis or treatment of disease. Reports may cover work on patients or healthy human subjects, in vivo animal experiments, studies of isolated organs or cultured cells, analysis of tissue extracts, NMR theory, experimental techniques, or instrumentation.