Hynynen K, McDannold N, Vykhodtseva N, Jolesz F A
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115, USA.
Radiology. 2001 Sep;220(3):640-6. doi: 10.1148/radiol.2202001804.
To determine if focused ultrasound beams can be used to locally open the blood-brain barrier without damage to surrounding brain tissue and if magnetic resonance (MR) imaging can be used to monitor this procedure.
The brains of 18 rabbits were sonicated (pulsed sonication) in four to six locations, with temporal peak acoustic power ranging from 0.2 to 11.5 W. Prior to each sonication, a bolus of ultrasonographic (US) contrast agent was injected into the ear vein of the rabbit. A series of fast or spoiled gradient-echo MR images were obtained during the sonications to monitor the temperature elevation and potential tissue changes. Contrast material-enhanced MR images obtained minutes after sonications and repeated 1-48 hours later were used to depict blood-brain barrier opening. Whole brain histologic evaluation was performed.
Opening of the blood-brain barrier was confirmed with detection of MR imaging contrast agent at the targeted locations. The lowest power levels used produced blood-brain barrier opening without damage to the surrounding neurons. Contrast enhancement correlated with the focal signal intensity changes in the magnitude fast spoiled gradient-echo MR images.
The blood-brain barrier can be consistently opened with focused ultrasound exposures in the presence of a US contrast agent. MR imaging signal intensity changes may be useful in the detection of blood-brain barrier opening during sonication.
确定聚焦超声束能否用于局部打开血脑屏障而不损伤周围脑组织，以及磁共振（MR）成像能否用于监测该过程。
对18只兔子的大脑在4至6个部位进行超声处理（脉冲超声），颞部峰值声功率范围为0.2至11.5W。在每次超声处理前，向兔子耳静脉注射一剂超声（US）造影剂。在超声处理过程中获取一系列快速或扰相梯度回波MR图像，以监测温度升高和潜在的组织变化。超声处理数分钟后及1 - 48小时后重复获取的对比剂增强MR图像用于描绘血脑屏障的开放情况。进行全脑组织学评估。
在目标位置检测到MR成像造影剂，证实血脑屏障已打开。使用的最低功率水平可实现血脑屏障开放且不损伤周围神经元。对比增强与快速扰相梯度回波MR图像中焦点信号强度变化相关。
在存在US造影剂的情况下，聚焦超声照射可使血脑屏障持续打开。MR成像信号强度变化可能有助于在超声处理过程中检测血脑屏障的开放。
