Impacts of RF shimming on local SAR caused by MRI 3T birdcage coil near femoral plate implants
Impacts of RF shimming on local SAR caused by MRI 3T birdcage coil near femoral plate implants
复制标题
射频匀场对股骨板植入物附近 MRI 3T 鸟笼线圈引起的局部 SAR 的影响
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Ji Chen
中科院分区：
文献类型：
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作者：
Qi Zeng;Ran Guo;Jianfeng Zheng;Ji Chen
对股骨板植入物在MRI 3 T鸟笼线圈中的局部比吸收率（SAR）进行了数值研究。在人体解剖模型中评估正交激励和RF匀场条件。所有结果均归一化为2 W/kg平均全身SAR，并使用Q-Matrices形式化方法来提高SAR计算效率。RF匀场程序使股骨区域的B1+场幅度均匀化。在射频匀场条件下，最差局部SAR点的值和位置都发生了变化。在正交激励条件下，最大局部SAR为573 W/kg，在RF匀场条件下为154。结果表明，观察到RF匀场对股骨接骨板植入物附近的局部SAR产生显著影响。
Numerical studies of local specific absorption rate (SAR) were conducted for femoral plate implants in MRI 3T birdcage coil. Both the quadrature excitation and RF shimming conditions were evaluated in anatomical models of human body. All the results were normalized to 2W/kg average whole body SAR and Q-Matrices formalism method was used to improve the SAR calculation efficiency. The RF shimming procedure homogenize the magnitude of B1+ field in femur region. Under RF shimming condition both the value and location of the worst local SAR point were changed. The maximum local SAR is 573 W/kg under quadrature excitation condition and 154 under RF shimming condition. As the results suggested, significant impacts on local SAR near femoral plate implants due to RF shimming were observed.