Schwenke Michael, Georgii Joachim, Preusser Tobias
Fraunhofer Institute for Medical Image Computing MEVIS, Bremen, Germany.
Fraunhofer Institute for Medical Image Computing MEVIS.
IEEE Trans Biomed Eng. 2017 Jul;64(7):1455-1468. doi: 10.1109/TBME.2016.2619741. Epub 2017 May 23.
Focused ultrasound (FUS) is rapidly gaining clinical acceptance for several target tissues in the human body. Yet, treating liver targets is not clinically applied due to a high complexity of the procedure (noninvasiveness, target motion, complex anatomy, blood cooling effects, shielding by ribs, and limited image-based monitoring). To reduce the complexity, numerical FUS simulations can be utilized for both treatment planning and execution. These use-cases demand highly accurate and computationally efficient simulations.
We propose a numerical method for the simulation of abdominal FUS treatments during respiratory motion of the organs and target. Especially, a novel approach is proposed to simulate the heating during motion by solving Pennes' bioheat equation in a computational reference space, i.e., the equation is mathematically transformed to the reference. The approach allows for motion discontinuities, e.g., the sliding of the liver along the abdominal wall.
Implementing the solver completely on the graphics processing unit and combining it with an atlas-based ultrasound simulation approach yields a simulation performance faster than real time (less than 50-s computing time for 100 s of treatment time) on a modern off-the-shelf laptop. The simulation method is incorporated into a treatment planning demonstration application that allows to simulate real patient cases including respiratory motion.
The high performance of the presented simulation method opens the door to clinical applications.
The methods bear the potential to enable the application of FUS for moving organs.
聚焦超声（FUS）在人体多个靶组织中迅速获得临床认可。然而，由于该操作的高度复杂性（非侵入性、靶标运动、解剖结构复杂、血液冷却效应、肋骨遮挡以及基于图像的监测有限），肝脏靶标的治疗尚未在临床上应用。为了降低复杂性，数值FUS模拟可用于治疗计划和执行。这些用例需要高度准确且计算高效的模拟。
我们提出了一种数值方法，用于模拟器官和靶标在呼吸运动期间的腹部FUS治疗。特别是，提出了一种新颖的方法，通过在计算参考空间中求解彭尼斯生物热方程来模拟运动期间的加热，即该方程在数学上被转换到参考空间。该方法允许运动不连续性，例如肝脏沿腹壁的滑动。
在一台现代的现成笔记本电脑上，将求解器完全在图形处理单元上实现，并将其与基于图谱的超声模拟方法相结合，可产生比实时更快的模拟性能（100秒治疗时间的计算时间少于50秒）。该模拟方法被纳入一个治疗计划演示应用程序中，该应用程序允许模拟包括呼吸运动在内的真实患者病例。
所提出的模拟方法的高性能为临床应用打开了大门。
这些方法具有使FUS应用于移动器官的潜力。
