Numerical simulation of SAR induced around Co-Cr-Mo hip prostheses in situ exposed to RF fields associated with 1.5 and 3 T MRI body coils
Numerical simulation of SAR induced around Co-Cr-Mo hip prostheses in situ exposed to RF fields associated with 1.5 and 3 T MRI body coils
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DOI：
10.1002/mrm.23304
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发表时间：
2012-09-01
影响因子：
3.3
通讯作者：
McRobbie, Donald
中科院分区：
文献类型：
--
作者：
Powell, John;Papadaki, Annie;McRobbie, Donald
当植入金属假体的患者接受 MR 手术时，射频场和假体装置之间的相互作用可能会导致假体周围组织的比吸收率 (SAR) 增加。在这项工作中，使用时域有限积分技术预测了由于以 64 或 128 MHz 驱动的通用鸟笼线圈产生的射频场，在成年男性和女性的解剖学真实体素模型中，双边 CoCrMo 合金髋关节假体周围的 SAR10g 分布。结果表明 SAR10g 的空间分布和最大值取决于身体模型、频率以及线圈相对于身体的位置。预计假肢四肢附近的 SAR10g 会增强。如果假体位于线圈外部，则接近假体的 SAR10g 值符合建议的限值。然而，当假肢位于线圈内时需要小心，因为当全身平均 SAR 为 2 W kg-1 时，靠近假肢肢体的预测 SAR10g 超过建议限值。遵守建议的限制可能需要降低时间平均输入功率。 Magn Reson Med，2012。(c) 2011 Wiley periodicals, Inc.
When patients with metallic prosthetic implants undergo an MR procedure, the interaction between the RF field and the prosthetic device may lead to an increase in specific absorption rate (SAR) in tissues surrounding the prosthesis. In this work, the distribution of SAR10g around bilateral CoCrMo alloy hip prostheses in situ in anatomically realistic voxel models of an adult male and female due to RF fields from a generic birdcage coil driven at 64 or 128 MHz are predicted using a time-domain finite integration technique. Results indicate that the spatial distribution and maximum values of SAR10g are dependent on body model, frequency, and the position of the coil relative to the body. Enhancement of SAR10g close to the extremities of a prosthesis is predicted. Values of SAR10g close to the prostheses are compliant with recommended limits if the prostheses are located outside the coil. However, caution is required when the prostheses are within the coil since the predicted SAR10g close to an extremity of a prosthesis exceeds recommended limits when the whole body averaged SAR is 2 W kg-1. Compliance with recommended limits is likely to require a reduction in the time averaged input power. Magn Reson Med, 2012. (c) 2011 Wiley Periodicals, Inc.