Susceptibility mapping of air, bone, and calcium in the head
Susceptibility mapping of air, bone, and calcium in the head
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DOI：
10.1002/mrm.25350
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发表时间：
2015-06-01
影响因子：
3.3
通讯作者：
Haacke, E. Mark
中科院分区：
文献类型：
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作者：
Buch, Sagar;Liu, Saifeng;Haacke, E. Mark
目的探讨利用短回波时间对鼻窦、骨骼和牙齿等高敏感值结构进行标测。方法采用梯度回波序列采集4组活体数据(TE1=2.5ms，TE2=5ms，TE3=7.5ms)。通过复数除法去除相位偏移项，在TE=2.5ms处产生相位。利用几何约束迭代算法，通过保留脑外组织中的相位信息，从展开的相位图像中生成磁化率图。通过在每个迭代步骤中使用预测相位更新无信号结构内部的遗漏相位信息，改善了灵敏度结果。使用三维脑模型和牙齿模型的模拟相位图像对该方法进行了验证。结果在加入脑外组织区域的相位信息后，无论是模型还是活体数据，都获得了改进的敏感度图。对于活体数据，空气(蝶窦)、骨和钙(牙)的平均磁化率(以ppm为单位)分别为：(鼻窦-组织)=+9.21.3，((骨-组织)=-2.1+/-0.6和((牙-组织))=-3.3+/-1.2。结论利用定量磁化率图可以成像信号很少或没有信号的高磁化率结构，并可用于改善背景场去除。Magn Reson Med 73：2185-2194,2015。(C)2014年威利期刊公司。
PurposeTo demonstrate the mapping of structures with high susceptibility values, such as the sinuses, bones and teeth, using short echo times.MethodsFour in vivo datasets were collected with a gradient-echo sequence (TE1=2.5 ms, TE2=5 ms and TE3=7.5 ms). Complex division was performed to remove the phase offset term and generate the phase at TE=2.5 ms. Susceptibility maps were generated from unwrapped phase images, using a geometry-constrained iterative algorithm, by preserving phase information in the extracerebral tissues. The susceptibility results were improved by updating the missing phase information inside structures with no signal using the predicted phase at each iteration step. Simulated phase images of a three-dimensional brain model and tooth phantom were used to validate the proposed method.ResultsImproved susceptibility maps were obtained once the phase information in the extracerebral tissue region was incorporated, for both the model and in vivo data. For in vivo data, the average susceptibilities of air (sphenoid sinus), bone and calcium (teeth) were found to be (in ppm): ((sinus-tissue))=+9.21.3, ((bone-tissue))=-2.1 +/- 0.6 and ((teeth-tissue))=-3.3 +/- 1.2, respectively.ConclusionHigh susceptibility structures with little or no signal can be imaged using quantitative susceptibility mapping and can be used to improve background field removal. Magn Reson Med 73:2185-2194, 2015. (c) 2014 Wiley Periodicals, Inc.