Vanderbilt University Institute of Imaging Science, Nashville, Tennessee, USA.
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
Magn Reson Med. 2018 Apr;79(4):2003-2013. doi: 10.1002/mrm.26862. Epub 2017 Aug 7.
To measure temperature over a large brain volume with fine spatiotemporal resolution.
A three-dimensional stack-of-stars echo-planar imaging sequence combining echo-planar imaging and radial sampling with golden angle spacing was implemented at 3T for proton resonance frequency-shift temperature imaging. The sequence acquires a 188x188x43 image matrix with 1.5x1.5x2.75 mm spatial resolution. Temperature maps were reconstructed using sensitivity encoding (SENSE) image reconstruction followed by the image domain hybrid method, and using the k-space hybrid method. In vivo temperature maps were acquired without heating to measure temperature precision in the brain, and in a phantom during high-intensity focused ultrasound sonication.
In vivo temperature standard deviation was less than 1°C at dynamic scan times down to 0.75 s. For a given frame rate, scanning at a minimum repetition time (TR) with minimum acceleration yielded the lowest standard deviation. With frame rates around 3 s, the scan was tolerant to a small number of receive coils, and temperature standard deviation was 48% higher than a standard two-dimensional Fourier transform temperature mapping scan, but provided whole-brain coverage. Phantom temperature maps with no visible aliasing were produced for dynamic scan times as short as 0.38 s. k-Space hybrid reconstructions were more tolerant to acceleration.
Three-dimensional stack-of-stars echo-planar imaging temperature mapping provides volumetric brain coverage and fine spatiotemporal resolution. Magn Reson Med 79:2003-2013, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
以精细的时空分辨率测量大脑的大面积温度。
在 3T 上实现了一种结合了 echo-planar imaging 和径向采样的三维星形叠层回波平面成像序列，采用黄金角度间隔进行质子磁共振频率位移温度成像。该序列采集了一个 188x188x43 的图像矩阵，空间分辨率为 1.5x1.5x2.75mm。使用灵敏度编码（SENSE）图像重建和图像域混合方法以及 k 空间混合方法重建温度图。在没有加热的情况下采集体内温度图，以测量大脑中的温度精度，并在高强度聚焦超声超声治疗期间在体模中进行。
在动态扫描时间低至 0.75s 的情况下，体内温度标准差小于 1°C。在给定的帧率下，以最小的重复时间（TR）和最小的加速度扫描可获得最低的标准差。在帧率约为 3s 时，扫描可以容忍少量的接收线圈，温度标准差比标准二维傅里叶变换温度映射扫描高 48%，但提供了全脑覆盖。对于动态扫描时间短至 0.38s 的体模温度图，没有可见的混叠。k 空间混合重建对加速度的容忍度更高。
三维星形叠层回波平面成像温度映射提供了体积大脑覆盖和精细的时空分辨率。磁共振医学 79:2003-2013, 2018。©2017 年国际磁共振学会。
