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首页> 外文期刊>Magnetic resonance in medicine: official journal of the Society of Magnetic Resonance in Medicine >Radiofrequency induced heating around aneurysm clips using a generic birdcage head coil at 7 Tesla under consideration of the minimum distance to decouple multiple aneurysm clips
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Radiofrequency induced heating around aneurysm clips using a generic birdcage head coil at 7 Tesla under consideration of the minimum distance to decouple multiple aneurysm clips

机译：在考虑到多个动脉瘤夹子的最小距离，在7特斯拉在7特斯拉在7个特斯拉，射频探测在动脉瘤夹子周围加热。

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Purpose To evaluate radiofrequency (RF) induced tissue heating around aneurysm clips during a 7T head MR examination and to determine the decoupling distance between multiple implanted clips. Methods A total of 120 RF exposure scenarios of clinical relevance were studied using specific absorption rate and temperature simulations. Variations between scenarios included 2 clips (18.8 and 51.5 mm length), 2 MR‐operating modes, 2 head models, and 3 thermoregulation models. Furthermore, a conservative approach was developed to allow for safe scans of patients with aneurysm clips even if detailed information on the implanted clip is unknown. A dedicated simulation‐based approach was applied to determine the decoupling distance between multiple implanted clips. Results For all 60 clinical scenarios with the 18.8‐mm‐long clip, the absolute tissue temperature remained below regulatory limits. For 15 of 60 scenarios with the 51.5‐mm‐long clip, limits were slightly exceeded (less than 1°C). The conservative approach led to a maximum time‐averaged input power of the RF coil of 3.3W. The corresponding B 1 + is 1.32 μT. A decoupling distance of 35 mm allows the aneurysm clips to be treated as uncoupled from one other. Conclusion Safe scanning conditions with respect to RF‐induced heating can be applied for single or decoupled aneurysm clips in a 7T ultra‐high field MRI setting. Multiple aneurysm clips separated by less than 35 mm need further investigations.
机译：目的在7T头MR检查期间评估射频（RF）诱导的动脉瘤夹子周围加热的组织，并确定多个植入夹之间的去耦距离。方法采用特定吸收率和温度模拟研究了总共120次临床相关性的临床相关性情景。场景之间的变化包括2个夹子（18.8和51.5 mm长度），2个MR操作模式，2个头部型号和3个热调用型号。此外，即使植入夹的详细信息未知，也开发了一种保守的方法以允许使用动脉瘤剪辑的患者的安全扫描。应用专用的基于模拟的方法来确定多个植入夹之间的去耦距离。结果所有60个临床情景，带18.8毫米长的夹子，绝对组织温度仍然低于监管限值。对于具有51.5毫米长的夹子的60个方案中的15个，限制略微超过（小于1°C）。保守方法导致了3.3W的RF线圈的最大时间平均输入功率。相应的B 1 +是1.32μT。去耦距离为35mm，允许动脉瘤夹待被处理为彼此的耦合。结论在7T超高场MRI设置中，可以施加相对于RF诱导的加热的安全扫描条件。多个动脉瘤夹子分开小于35 mm，需要进一步调查。

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