论文标题
一种几何方法，用于分离具有各向同性磁化率的幻影中磁化率和化学位移/交换的影响
A geometric approach to separate the effects of magnetic susceptibility and chemical shift/exchange in a phantom with isotropic magnetic susceptibility
论文作者
论文摘要
目的：用各向同性磁敏感性在幻影中分离磁敏感性和化学位移/交换的影响。为了产生化学移位/交换校正的定量敏感性映射（QSM）。 理论和方法：磁化率和化学位移/交换是材料的特性。已知两者都会诱导MRI的共振频移。在当前的QSM中，易感性是从频移中重建的，忽略了化学位移/交换的贡献。在这项工作中，使用平均值无效（各向同性）敏感性效应的事实开发了一种简单的几何方法，该方法平均从三个正交B0方向进行频移图来生成化学移位/交换图。从总频移中减去所得的化学移位/交换图，仅从易感性中产生频移图。最后，使用QSM算法将该频移图重建为易感图。该方法在数值模拟中验证，并应用于橄榄油，牛血清白蛋白，铁蛋白和氧化铁溶液的幻影实验。 结果：模拟和实验都证实，该方法成功地分开了易感性和化学位移/交换的贡献，报告了橄榄油的敏感性和化学位移/交换（易感性：0.62 ppm，化学移位：-3.60 ppm），牛静脉毒素（易感性：-059 ppm，化学移动：0.25 ppm）（0.25 ppm）（0.25 ppm），fpm：0.25 ppm） ppm，化学位移：-0.005 ppm）和氧化铁（易感性：0.30 ppm，化学位移：-0.039 ppm）溶液。 结论：所提出的方法成功地将各向同性磁敏感性的幻象中的易感性和化学位移/交换分开。
Purpose: To separate the effects of magnetic susceptibility and chemical shift/exchange in a phantom with isotropic magnetic susceptibility. To generate a chemical shift/exchange-corrected quantitative susceptibility mapping (QSM) result. Theory and Methods: Magnetic susceptibility and chemical shift/exchange are the properties of a material. Both are known to induce the resonance frequency shift in MRI. In current QSM, the susceptibility is reconstructed from the frequency shift, ignoring the contribution of the chemical shift/exchange. In this work, a simple geometric approach, which averages the frequency shift maps from three orthogonal B0 directions to generate a chemical shift/exchange map, is developed using the fact that the average nullifies the (isotropic) susceptibility effects. The resulting chemical shift/exchange map is subtracted from the total frequency shift, producing a frequency shift map solely from susceptibility. Finally, this frequency shift map is reconstructed to a susceptibility map using a QSM algorithm. The proposed method is validated in numerical simulations and applied to phantom experiments with olive oil, bovine serum albumin, ferritin, and iron oxide solutions. Results: Both simulations and experiments confirm that the method successfully separates the contributions of the susceptibility and chemical shift/exchange, reporting the susceptibility and chemical shift/exchange of olive oil (susceptibility: 0.62 ppm, chemical shift: -3.60 ppm), bovine serum albumin (susceptibility: -0.059 ppm, chemical shift: 0.008 ppm), ferritin (susceptibility: 0.125 ppm, chemical shift: -0.005 ppm), and iron oxide (susceptibility: 0.30 ppm, chemical shift: -0.039 ppm) solutions. Conclusion: The proposed method successfully separates the susceptibility and chemical shift/exchange in phantoms with isotropic magnetic susceptibility.
