Shmueli Karin, Thomas David L, Ordidge Roger J
Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1065, USA.
J Magn Reson Imaging. 2007 Jul;26(1):202-7. doi: 10.1002/jmri.20993.
To design and construct an anthropomorphic head phantom using materials of appropriate magnetic susceptibility and air spaces of realistic dimensions, with the aim of reproducing the susceptibility artifacts found in the human brain.
The phantom is based on a plastic skull filled with MnCl2-doped water. Materials to mimic soft tissue (wax) and bone (plastic skull) were chosen based on mass susceptibility measurements using a superconducting quantum interference device (SQUID) magnetometer. The phantom was designed for and evaluated at 4.7T using field mapping and echo-planar imaging (EPI).
The main magnetic field (B0) maps of the phantom resemble those of four volunteers' brains and have similar standard deviations (SDs). Maps of the B0 field gradients in the phantom and real brains are also similar. The phantom has relaxation times close to those of brain tissue at 4.7T. Gradient-echo (GE)-EPI images of the phantom suffer from susceptibility artifacts comparable to those in real heads and at anatomically realistic locations.
The phantom is a useful tool for evaluating and comparing different susceptibility artifact reduction techniques. The phantom could also be used to test CT-MRI coregistration in the presence of susceptibility artifacts since the water-filled brain cavity is both CT- and MR-visible.
使用具有适当磁化率的材料和实际尺寸的空气间隙设计并构建一个仿真人头模型，旨在重现人类大脑中发现的磁化率伪影。
该模型基于一个填充有掺有MnCl2的水的塑料颅骨。根据使用超导量子干涉装置（SQUID）磁力计进行的质量磁化率测量，选择了模拟软组织（蜡）和骨骼（塑料颅骨）的材料。该模型专为4.7T设计，并使用场图绘制和回波平面成像（EPI）进行评估。
该模型的主磁场（B0）图与四名志愿者大脑的图相似，且具有相似的标准差（SD）。该模型和真实大脑中B0场梯度的图也相似。该模型在4.7T时的弛豫时间与脑组织的弛豫时间相近。该模型的梯度回波（GE）-EPI图像所遭受的磁化率伪影与真实头部在解剖学上实际位置处的伪影相当。
该模型是评估和比较不同磁化率伪影减少技术的有用工具。由于充满水的脑腔在CT和MR下均可见，该模型还可用于在存在磁化率伪影的情况下测试CT-MRI配准。
