Todd Nick, Prakash Jaya, Odéen Henrik, de Bever Josh, Payne Allison, Yalavarthy Phaneendra, Parker Dennis L
Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
Magn Reson Med. 2014 Apr;71(4):1394-404. doi: 10.1002/mrm.24783. Epub 2013 May 13.
To extend the previously developed temporally constrained reconstruction (TCR) algorithm to allow for real-time availability of three-dimensional (3D) temperature maps capable of monitoring MR-guided high intensity focused ultrasound applications.
A real-time TCR (RT-TCR) algorithm is developed that only uses current and previously acquired undersampled k-space data from a 3D segmented EPI pulse sequence, with the image reconstruction done in a graphics processing unit implementation to overcome computation burden. Simulated and experimental data sets of HIFU heating are used to evaluate the performance of the RT-TCR algorithm.
The simulation studies demonstrate that the RT-TCR algorithm has subsecond reconstruction time and can accurately measure HIFU-induced temperature rises of 20°C in 15 s for 3D volumes of 16 slices (RMSE = 0.1°C), 24 slices (RMSE = 0.2°C), and 32 slices (RMSE = 0.3°C). Experimental results in ex vivo porcine muscle demonstrate that the RT-TCR approach can reconstruct temperature maps with 192 × 162 × 66 mm 3D volume coverage, 1.5 × 1.5 × 3.0 mm resolution, and 1.2-s scan time with an accuracy of ±0.5°C.
The RT-TCR algorithm offers an approach to obtaining large coverage 3D temperature maps in real-time for monitoring MR-guided high intensity focused ultrasound treatments.
扩展先前开发的时间约束重建（TCR）算法，以实现能够监测磁共振引导高强度聚焦超声应用的三维（3D）温度图的实时可用性。
开发了一种实时TCR（RT-TCR）算法，该算法仅使用来自三维分段回波平面成像（EPI）脉冲序列的当前和先前采集的欠采样k空间数据，并在图形处理单元上进行图像重建以克服计算负担。使用高强度聚焦超声（HIFU）加热的模拟和实验数据集来评估RT-TCR算法的性能。
模拟研究表明，RT-TCR算法的重建时间不到一秒，对于16层、24层和32层的3D体积，能够在15秒内准确测量HIFU引起的20°C温度升高（均方根误差分别为0.1°C、0.2°C和0.3°C）。在离体猪肌肉中的实验结果表明，RT-TCR方法能够以1.2秒的扫描时间重建覆盖192×162×66 mm三维体积、分辨率为1.5×1.5×3.0 mm且精度为±0.5°C的温度图。
RT-TCR算法提供了一种实时获取大覆盖范围3D温度图的方法，用于监测磁共振引导高强度聚焦超声治疗。
