Evaluation of three-dimensional temperature distributions produced by a low-frequency transcranial focused ultrasound system within ex vivo human skulls.
Evaluation of three-dimensional temperature distributions produced by a low-frequency transcranial focused ultrasound system within ex vivo human skulls.
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DOI：
10.1109/tuffc.2010.1644
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发表时间：
2010-09
期刊：
影响因子：
--
通讯作者：
Jolesz F
中科院分区：
文献类型：
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作者：
McDannold N;Park EJ;Mei CS;Zadicario E;Jolesz F
经颅磁共振引导聚焦超声（TcMRgFUS）提供了一种潜在的非侵入性替代手术切除和其他治疗脑部疾病。低频超声的使用为TcMRgFUS提供了几个优点，但可能受到反射和驻波效应的限制，这些效应可能会导致颅骨腔内的二次热点。这项工作的目的是使用体积MR温度成像（MRTI）和离体人体颅骨填充组织模仿体模材料，以搜索加热远离焦点，可能会发生在超声处理与TcMRgFUS系统作为反射或驻波效应的结果。在120 s超声处理期间，在两个不同颅骨的12个不同位置的整个颅骨体积内监测加热。该装置使用在220 kHz下操作的半球阵列。在每个位置进行多次超声处理，同时改变MRTI切片位置，以提供颅骨腔的完全覆盖。使用自动化例程评估MRTI以检测似乎被超声加热的体素区域。没有发现温升超过15%或更高的次级热点。MRTI噪声水平阻止了对温升较低的可能热点的识别。这些结果表明，显着的二次加热由这个TcMRgFUS系统在远离焦点的点是不常见的。
Transcranial MR-guided Focused Ultrasound (TcMRgFUS) provides a potential noninvasive alternative to surgical resection and for other treatments for brain disorders. Use of low frequency ultrasound provides several advantages for TcMRgFUS, but is potentially limited by reflection and standing wave effects that may cause secondary hotspots within the skull cavity. The purpose of this work was to use volumetric MR temperature imaging (MRTI) and ex vivo human skulls filled with tissue-mimicking phantom material to search for heating distant from the focal point that may occur during sonication with a TcMRgFUS system as a result of reflections or standing wave effects. Heating during 120 s sonications was monitored within the entire skull volume for 12 different locations in two different skulls. The setup used a hemispheric array operating at 220 kHz. Multiple sonications were delivered at each location while varying the MRTI slice positions in order to provide full coverage of the skull cavity. An automated routine was used evaluate the MRTI to detect voxel regions that appeared to be heated by ultrasound. No secondary hotspots with a temperature rise of 15% or more of the focal heating were found. The MRTI noise level prevented the identification of possible hotspots with a lower temperature rise. These results suggest that significant secondary heating by this TcMRgFUS system at points distant from the focal point are not common.