Woo Myung Kyun, DelaBarre Lance, Lee Byeong-Yeul, Waks Matt, Lagore Russell Luke, Radder Jerahmie, Eryaman Yigitcan, Ugurbil Kamil, Adriany Gregor
Center for Magnetic Resonance and Research, University of Minnesota, Minneapolis, Minnesota, USA.
National Institute of Allergy and Infectious Diseases (NIAID), Integrated Research Facility (IRF), Frederick, Maryland, USA.
IEEE Access. 2020;8:203555-203563. doi: 10.1109/access.2020.3036598. Epub 2020 Nov 6.
We evaluated a 16-channel loop + dipole (LD) transceiver antenna array with improved specific absorption rate (SAR) efficiency for 10.5 Tesla (T) human head imaging apsplications. Three different array designs with equal inner dimensions were considered: an 8-channel dipole antenna, an 8-channel loop, and a 16-channel LD antenna arrays. Signal-to-noise ratio (SNR) and B efficiency (in units of μT per √W) were simulated and measured in 10.5 T magnetic resonance imaging (MRI) experiments. For the safety validation, 10 g SAR and SAR efficiency (defined as the B over √ (peak 10 g SAR)) were calculated through simulation. Finally, high resolution porcine brain images were acquired with the 16-channel LD antenna array, including a fast turbo-spin echo (TSE) sequence incorporating B1 shimming techniques. Both the simulation and experiments demonstrated that the combined 16-channel LD antenna array showed similar B efficiency compared to the 8-channel dipole antenna and the 8-channel loop arrays in a circular polarized (CP) mode. In a central 2 mm × 2 mm region of the phantom, however, the 16-channel LD antenna array showed an improvement in peak 10 g SAR of 27.5 % and 32.5 % over the 8-channel dipole antenna and the 8-channel loop arrays, respectively. We conclude that the proposed 16-channel head LD antenna array design is capable of achieving ~7% higher SAR efficiency at 10.5 T compared to either the 8-channel loop-only or the 8-channel dipole-only antenna arrays of the same dimensions.
我们评估了一种16通道环形+偶极子（LD）收发天线阵列，该阵列针对10.5特斯拉（T）人体头部成像应用提高了比吸收率（SAR）效率。考虑了三种具有相同内部尺寸的不同阵列设计：一个8通道偶极子天线、一个8通道环形天线和一个16通道LD天线阵列。在10.5T磁共振成像（MRI）实验中对信噪比（SNR）和B效率（以每√W的μT为单位）进行了模拟和测量。为了进行安全验证，通过模拟计算了10g SAR和SAR效率（定义为B除以√（峰值10g SAR））。最后，使用16通道LD天线阵列采集了高分辨率猪脑图像，包括结合了B1匀场技术的快速涡轮自旋回波（TSE）序列。模拟和实验均表明，在圆极化（CP）模式下，组合式16通道LD天线阵列与8通道偶极子天线和8通道环形阵列相比，显示出相似的B效率。然而，在体模的中心2mm×2mm区域，16通道LD天线阵列的峰值10g SAR分别比8通道偶极子天线和8通道环形阵列提高了27.5%和32.5%。我们得出结论，与相同尺寸的仅8通道环形或仅8通道偶极子天线阵列相比，所提出的16通道头部LD天线阵列设计在10.5T时能够实现高出约7%的SAR效率。
