Cavitation-based third ventriculostomy using MRI-guided focused ultrasound
Cavitation-based third ventriculostomy using MRI-guided focused ultrasound
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DOI：
10.3171/2013.8.jns13969
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发表时间：
2013-12-01
影响因子：
4.1
通讯作者：
Hynynen, Kullervo
中科院分区：
文献类型：
--
作者：
Alkins, Ryan;Huang, Yuexi;Hynynen, Kullervo
对象。经颅聚焦超声作为一种微创治疗一系列颅内病变的方法越来越受到重视。在比热消融更高的峰值稀薄压力下，聚焦超声可以引发惯性空化，并通过组织元素的分离在大脑中产生孔洞。作者研究了mri引导下聚焦超声行第三脑室造瘘术的技术可行性，作为脑积水第三脑室内镜造瘘术的一种可能的无创替代方法。对体重13-19 kg的雄性猪进行颅骨切除术，暴露幕上脑，保留硬脑膜完整。7头猪通过颅骨切除术治疗，2头猪通过体外人头骨放置在光束路径中治疗。采用t2加权MRI序列进行配准和靶向。对于经颅治疗，使用CT扫描来纠正由于颅骨造成的光束畸变，并保持小而高强度的聚焦。超声在650千赫和230千赫的强度范围内进行，并根据模拟和实验数据估计原位压力，以建立大脑组织分离的阈值。在650 kHz的开颅动物中，需要峰值压力>= 22.7 MPa持续1秒才能可靠地创建脑室造口术。在这个频率下，ExAblate 4000无法产生所需的强度来分离组织，尽管空化已经开始。在230 kHz时，脑室造瘘术成功通过颅骨，峰值压力为8.8 mpa。这是第一个研究表明可以使用超声进行完全无创的第三脑室造口术。这可能为未来的研究铺平道路，并最终为脑脊液在脑内的通信提供一种替代方法，包括透明隔或脑室内膜穿孔。
Object. Transcranial focused ultrasound is increasingly being investigated as a minimally invasive treatment for a range of intracranial pathologies. At higher peak rarefaction pressures than those used for thermal ablation, focused ultrasound can initiate inertial cavitation and create holes in the brain by fractionation of the tissue elements. The authors investigated the technical feasibility of using MRI-guided focused ultrasound to perform a third ventriculostomy as a possible noninvasive alternative to endoscopic third ventriculostomy for hydrocephalus.Methods. A craniectomy was performed in male pigs weighing 13-19 kg to expose the supratentorial brain, leaving the dura mater intact. Seven pigs were treated through the craniectomy, while 2 pigs were treated through ex vivo human skulls placed in the beam path. Registration and targeting was done using T2-weighted MRI sequences. For transcranial treatments a CT scan was used to correct the beam from aberrations due to the skull and maintain a small, high-intensity focus. Sonications were performed at both 650 kHz and 230 kHz at a range of intensities, and the in situ pressures were estimated both from simulations and experimental data to establish a threshold for tissue fractionation in the brain.Results. In craniectomized animals at 650 kHz, a peak pressure >= 22.7 MPa for 1 second was needed to reliably create a ventriculostomy. Transcranially at this frequency the ExAblate 4000 was unable to generate the required intensity to fractionate tissue, although cavitation was initiated. At 230 kHz, ventriculostomy was successful through the skull with a peak pressure of 8.8 MPa.Conclusions. This is the first study to suggest that it is possible to perform a completely noninvasive third ventriculostomy using ultrasound. This may pave the way for future studies and eventually provide an alternative means for the creation of CSF communications in the brain, including perforation of the septum pellucidum or intraventricular membranes.