Effect of field strength on RF power deposition near conductive leads: A simulation study of SAR in DBS lead models during MRI at 1.5 T-10.5 T.
Effect of field strength on RF power deposition near conductive leads: A simulation study of SAR in DBS lead models during MRI at 1.5 T-10.5 T.
复制标题
场强对RF功率沉积附近导电线的影响：MRI在1.5 T-10.5 T的MRI期间对SAR中的SAR进行的模拟研究。
DOI：
10.1371/journal.pone.0280655
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发表时间：
2023
期刊：
影响因子：
3.7
通讯作者：
Golestanirad L
中科院分区：
文献类型：
--
作者：
Kazemivalipour E;Sadeghi-Tarakameh A;Keil B;Eryaman Y;Atalar E;Golestanirad L
自近40年前磁共振成像（MRI）问世以来，人们一直在寻求更高的磁场强度。这样做有很强的动机，因为增加磁场强度会增加图像的信噪比。然而，与低场相比，在高场和超高场MRI（即≥3t）下确保患者安全变得更具挑战性。对于使用导电植入物的患者，比如那些使用深部脑刺激（DBS）设备的患者，这个问题更加严重，因为植入的铅尖端周围可能会出现过度的局部加热。尽管在评估1.5 T MRI期间植入物的射频（RF）加热方面做了大量工作，但缺乏一项系统检查场强和各种暴露限制对射频加热影响的比较研究。本研究旨在进行数值模拟，系统地比较MRI期间在常见临床和超高场强（即1.5、3、7和10.5 t）下DBS导联模型附近的射频功率沉积。此外，我们通过对B1+或整体头部特定吸收率（SAR）施加限制来评估不同暴露限制对射频功率沉积的影响，因为这两种暴露限制通常出现在MRI指南中。基于植入DBS装置的患者术后CT图像，我们创建了33个独特的DBS引线模型，并进行了电磁模拟，以评估射频暴露在64 MHz （1.5 T）至447 MHz （10.5 T）频率下引线尖端周围组织的射频能量SAR。射频暴露是通过基于我们机构建立的物理原型创建的真实MRI射频线圈模型来实现的。我们系统地检查了不同频率下局部SAR的分布，并调整了输入线圈的功率以限制B1+或全局头SAR。当全局头SAR受到限制时，较高谐振频率的MRI RF线圈在引线尖端周围产生较低的SAR。当对B1+施加约束时，趋势发生了逆转。在较高的静电场下，对于有导电性导线的患者，MRI并不一定比低静电场更危险。具体来说，当一个保守的安全标准，如对全局SAR的约束，较高谐振频率的线圈倾向于在植入导线周围产生较低的局部SAR，这是由于B1+和E场水平的降低。
Since the advent of magnetic resonance imaging (MRI) nearly four decades ago, there has been a quest for ever-higher magnetic field strengths. Strong incentives exist to do so, as increasing the magnetic field strength increases the signal-to-noise ratio of images. However, ensuring patient safety becomes more challenging at high and ultrahigh field MRI (i.e., ≥3 T) compared to lower fields. The problem is exacerbated for patients with conductive implants, such as those with deep brain stimulation (DBS) devices, as excessive local heating can occur around implanted lead tips. Despite extensive effort to assess radio frequency (RF) heating of implants during MRI at 1.5 T, a comparative study that systematically examines the effects of field strength and various exposure limits on RF heating is missing. This study aims to perform numerical simulations that systematically compare RF power deposition near DBS lead models during MRI at common clinical and ultra-high field strengths, namely 1.5, 3, 7, and 10.5 T. Furthermore, we assess the effects of different exposure constraints on RF power deposition by imposing limits on either the B1+ or global head specific absorption rate (SAR) as these two exposure limits commonly appear in MRI guidelines. We created 33 unique DBS lead models based on postoperative computed tomography (CT) images of patients with implanted DBS devices and performed electromagnetic simulations to evaluate the SAR of RF energy in the tissue surrounding lead tips during RF exposure at frequencies ranging from 64 MHz (1.5 T) to 447 MHz (10.5 T). The RF exposure was implemented via realistic MRI RF coil models created based on physical prototypes built in our institutions. We systematically examined the distribution of local SAR at different frequencies with the input coil power adjusted to either limit the B1+ or the global head SAR. The MRI RF coils at higher resonant frequencies generated lower SARs around the lead tips when the global head SAR was constrained. The trend was reversed when the constraint was imposed on B1+. At higher static fields, MRI is not necessarily more dangerous than at lower fields for patients with conductive leads. Specifically, when a conservative safety criterion, such as constraints on the global SAR, is imposed, coils at a higher resonant frequency tend to generate a lower local SAR around implanted leads due to the decreased B1+ and, by proxy, E field levels.
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影响因子：
3.9
作者：
Mattei, Eugenio;Triventi, Michele;Calcagnini, Giovanni;Censi, Federica;Kainz, Wolfgang;Mendoza, Gonzalo;Bassen, Howard I.;Bartolini, Pietro
通讯作者：
Bartolini, Pietro
影响因子：
3.3
作者：
Golestanirad, Laleh;Kazemivalipour, Ehsan;Kirsch, John
通讯作者：
Kirsch, John
影响因子：
3.3
作者：
Collins, CM;Liu, W;Smith, MB
通讯作者：
Smith, MB
影响因子：
5.7
作者：
Kazemivalipour, Ehsan;Keil, Boris;Golestanirad, Laleh
通讯作者：
Golestanirad, Laleh
影响因子：
3.3
作者：
Golestanirad L;Rahsepar AA;Kirsch JE;Suwa K;Collins JC;Angelone LM;Keil B;Passman RS;Bonmassar G;Serano P;Krenz P;DeLap J;Carr JC;Wald LL
通讯作者：
Wald LL