Radio-Frequency Safety Assessment of Stents in Blood Vessels During Magnetic Resonance Imaging.
Radio-Frequency Safety Assessment of Stents in Blood Vessels During Magnetic Resonance Imaging.
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DOI：
10.3389/fphys.2018.01439
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发表时间：
2018
影响因子：
4
通讯作者：
Iacono MI
中科院分区：
文献类型：
--
作者：
Fujimoto K;Angelone LM;Lucano E;Rajan SS;Iacono MI
目的：本研究的目的是调查高分辨率详细解剖模型的需求，以正确估计磁共振成像 (MRI) 期间的射频 (RF) 安全性。金属植入设备附近的射频感应加热取决于与设备相切的电场 (Etan)。对解剖模型的血管中的 Etan 和比吸收率 (SAR) 进行了分析，以了解标准凝胶体模是否准确地代表了由于支架等被动血管植入物而导致的组织中的潜在热量。方法：使用射频鸟笼体线圈的数值模型和自然空间分辨率为 1 mm3 的解剖学真实虚拟患者来模拟 64 MHz 的体内电场（1.5 T MRI 系统）。计算血管内 SAR 的最大值，并将其与 ASTM 凝胶体模数值模型中的峰值进行比较，以查看简化且均匀的凝胶体模的结果是否与解剖模型的结果具有可比性。还计算了选定的血管内支架轨迹的 Etan 值，并与 ASTM 结果进行比较。结果：血管中的峰值 SAR 值比 ASTM 标准凝胶体模中的值高出十倍。在临床上重要的解剖位置发现了峰值，支架按照预期用途植入该位置。此外，Etan 结果表明，体积平均 SAR 值可能不足以评估射频安全性。结论：与标准测试方法相比，高分辨率解剖模型的计算模型表明入射电场具有更高的值。进一步的研究将有助于开发反映临床实际情况的稳健的安全测试方法。
Purpose: The purpose of this study was to investigate the need for high-resolution detailed anatomical modeling to correctly estimate radio-frequency (RF) safety during magnetic resonance imaging (MRI). RF-induced heating near metallic implanted devices depends on the electric field tangential to the device (Etan). Etan and specific absorption rate (SAR) were analyzed in blood vessels of an anatomical model to understand if a standard gel phantom accurately represents the potential heating in tissues due to passive vascular implants such as stents. Methods: A numerical model of an RF birdcage body coil and an anatomically realistic virtual patient with a native spatial resolution of 1 mm3 were used to simulate the in vivo electric field at 64 MHz (1.5 T MRI system). Maximum values of SAR inside the blood vessels were calculated and compared with peaks in a numerical model of the ASTM gel phantom to see if the results from the simplified and homogeneous gel phantom were comparable to the results from the anatomical model. Etan values were also calculated in selected stent trajectories inside blood vessels and compared with the ASTM result. Results: Peak SAR values in blood vessels were up to ten times higher than those found in the ASTM standard gel phantom. Peaks were found in clinically significant anatomical locations, where stents are implanted as per intended use. Furthermore, Etan results showed that volume-averaged SAR values might not be sufficient to assess RF safety. Conclusion: Computational modeling with a high-resolution anatomical model indicated higher values of the incident electric field compared to the standard testing approach. Further investigation will help develop a robust safety testing method which reflects clinically realistic conditions.
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影响因子：
3.7
作者：
Santoro D;Winter L;Müller A;Vogt J;Renz W;Ozerdem C;Grässl A;Tkachenko V;Schulz-Menger J;Niendorf T
通讯作者：
Niendorf T
影响因子：
4.4
作者：
Park, Sung-Min;Kamondetdacha, Rungkiet;Nyenhuis, John A.
通讯作者：
Nyenhuis, John A.
影响因子：
3.3
作者：
Homann, H.;Boernert, P.;Graesslin, I.
通讯作者：
Graesslin, I.
影响因子：
6.4
作者：
Shellock, FG;Forder, JR
通讯作者：
Forder, JR
影响因子：
4.4
作者：
Adams, GJ;Baltazar, U;Morrisett, JD
通讯作者：
Morrisett, JD