Payne Allison, Minalga Emilee, Merrill Robb, Parker Dennis L, Hadley J Rock
Utah Center for Advanced Imaging Research, Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, Utah, 84108, USA.
Med Phys. 2020 Jun;47(6):2350-2355. doi: 10.1002/mp.14138. Epub 2020 Apr 6.
To evaluate the effect of a focused ultrasound transducer position and ground plane configuration on magnetic resonance image quality.
The effect of transducer position with respect to the MRI B0 field and the radiofrequency receive coils was evaluated in a breast-specific MRgFUS system with an integrated RF phased-array coil. Image signal-to-noise ratio was evaluated at different transducer locations. The effect of ultrasound transducer ground plane configuration was evaluated using a replica transducer with 12 ground plane configurations. All evaluations were performed at 3 Tesla.
Both transducer position and ground plane configuration were found to have a considerable effect on overall image SNR. A 67% increase in SNR was achieved by positioning the transducer face perpendicular to the B0 field. A 25% increase in SNR was achieved by segmenting the replica transducer ground plane from one continuous plane to nine individual segments.
Advances in focused ultrasound hardware allow for integrated radiofrequency MRI coils as well as adjustable transducer positioning. The placement of the ultrasound transducer with respect to both the magnetic field and RF coils can have a considerable effect on image SNR and the resulting MR images that are used for MR-guided focused ultrasound treatment planning, monitoring and assessment.
评估聚焦超声换能器位置和接地平面配置对磁共振图像质量的影响。
在具有集成射频相控阵线圈的乳腺专用磁共振引导聚焦超声（MRgFUS）系统中，评估换能器相对于MRI B0场和射频接收线圈的位置影响。在不同换能器位置评估图像信噪比。使用具有12种接地平面配置的复制换能器评估超声换能器接地平面配置的影响。所有评估均在3特斯拉下进行。
发现换能器位置和接地平面配置对整体图像信噪比均有显著影响。通过将换能器面垂直于B0场放置，信噪比提高了67%。通过将复制换能器接地平面从一个连续平面分割为九个单独部分，信噪比提高了25%。
聚焦超声硬件的进步允许集成射频MRI线圈以及可调节的换能器定位。超声换能器相对于磁场和射频线圈的放置对图像信噪比以及用于磁共振引导聚焦超声治疗计划、监测和评估的所得磁共振图像可能有显著影响。
