Improved MRI R2* Relaxometry of Iron-Loaded Liver with Noise Correction
Improved MRI R2* Relaxometry of Iron-Loaded Liver with Noise Correction
复制标题
DOI：
10.1002/mrm.24607
复制
发表时间：
2013-12-01
影响因子：
3.3
通讯作者：
Firmin, David N.
中科院分区：
文献类型：
--
作者：
Feng, Yanqiu;He, Taigang;Firmin, David N.
准确和可重复的MRI R-2*弛豫测量法用于组织铁定量在管理输血依赖患者中很重要。MRI数据通常使用阵列线圈获取，并通过平方根算法重建，因此，测量信号遵循非中心chi分布。在本研究中，提出了肝脏R-2*量化的两种噪声校正模型：在存在非中心chi噪声的情况下，将信号拟合到第一矩和将平方信号拟合到第二矩。在模拟和体内数据上，将这两种模型与广泛应用的偏移和截断模型进行了比较。结果表明，肝脏R-2*的慢衰成分主要是由噪声引起的。由于不正确地添加了一个常数来考虑慢衰减分量，偏移模型大大高估了R-2*值。截断模型通常通过拟合远高于噪声水平的初始数据来消除主要误差来源，从而产生准确的R-2*测量值，但由于获得非常短的回波时间图像的序列限制，因此低估了非常高的R-2*值。通过正确解决噪声问题，第一和第二矩噪声校正模型不断产生准确和精确的R-2*测量。中华医学杂志，2013,31(2):557 - 557。(c) 2013 Wiley Periodicals, Inc.；
Accurate and reproducible MRI R-2* relaxometry for tissue iron quantification is important in managing transfusion-dependent patients. MRI data are often acquired using array coils and reconstructed by the root-sum-square algorithm, and as such, measured signals follow the noncentral chi distribution. In this study, two noise-corrected models were proposed for the liver R-2* quantification: fitting the signal to the first moment and fitting the squared signal to the second moment in the presence of the noncentral chi noise. These two models were compared with the widely implemented offset and truncation models on both simulation and in vivo data. The results demonstrated that the slow decay component of the liver R-2* was mainly caused by the noise. The offset model considerably overestimated R-2* values by incorrectly adding a constant to account for the slow decay component. The truncation model generally produced accurate R-2* measurements by only fitting the initial data well above the noise level to remove the major source of errors, but underestimated very high R-2* values due to the sequence limit of obtaining very short echo time images. Both the first and second-moment noise-corrected models constantly produced accurate and precise R-2* measurements by correctly addressing the noise problem. Magn Reson Med 70:1765-1774, 2013. (c) 2013 Wiley Periodicals, Inc.