Limits of detection of SPIO at 3.0 T using T2* relaxometry
Limits of detection of SPIO at 3.0 T using T2* relaxometry
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DOI：
10.1002/mrm.20435
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发表时间：
2005-05-01
影响因子：
3.3
通讯作者：
Schaeffter, T
中科院分区：
文献类型：
--
作者：
Dahnke, H;Schaeffter, T
用于定量MR成像的T-2* 弛豫测量受到大尺度场不均匀性的强烈阻碍，这导致信号损失和弛豫速率R-2* 的高估。这对于氧化铁造影剂分布的灵敏检测特别重要。为了获得T-2* 的精确测量，应用了主场不均匀性校正：主场不均匀性从多层T-2* 弛豫测量数据中导出，并用作迭代优化的初始值，通过迭代优化，针对每个体素校正弛豫信号。这些校正的T-2* 图显示了局部场变化的影响降低，并包含有关局部SPIO浓度的信息。该方法在体模上进行了测试，使用T-2* 弛豫法对SPIO标记细胞的检测限在志愿者脑中估计为120 x 10（3）个细胞/mL（2.4 μ g Fe/mL），在肝脏中估计为385 x 10（3）个细胞/mL（8 μ g Fe/mL）。Magn Reson Med 53：1202-1206，2005. (c)2005年Wiley-Liss，Inc.
T-2* relaxometry for quantitative MR imaging is strongly hampered by large-scale field inhomogeneities, which lead to signal losses and an overestimation of the relaxation rate R-2*. This is of particular importance for the sensitive detection of iron oxide contrast agent distributions. To derive an accurate measurement of T-2*, a main field inhomogeneity correction is applied: the main field inhomogeneity is derived from multislice T-2* relaxometry data and used as an initial value for an iterative optimization, by which the relaxation signal is corrected for each voxel. These corrected T-2* maps show reduced influence of the local field variation and contain information about the local SPIO concentration. The method was tested on phantoms and the limit of detection of SPIO labeled cells using T-2* relaxometry was estimated in volunteers to be 120 x 10(3) cells/mL (2.4 mu g Fe/mL) in the brain and 385 x 10(3) cells/mL (8 mu g Fe/mL) in the liver. Magn Reson Med 53:1202-1206, 2005. (c) 2005 Wiley-Liss, Inc.