IEEE Trans Biomed Eng. 2020 Jan;67(1):256-267. doi: 10.1109/TBME.2019.2912146. Epub 2019 Apr 18.
To design and simulate the performance of two spine-specific phased arrays in sonicating targets spanning the thoracic spine, with the objective of efficiently producing controlled foci in the spinal canal.
Two arrays (256 elements each, 500 kHz) were designed using multi-layered ray acoustics simulation: a four-component array with dedicated components for sonicating via the paravertebral and transvertebral paths, and a two-component array with spine-specific adaptive focusing. Mean array efficiency (canal focus pressure/water focus pressure) was evaluated using forward simulation in neutral and flexed spines to investigate methods that reduce spine-induced insertion loss. Target-specific four-component array reconfiguration and lower frequency sonication (250 kHz) were tested to determine their effects on array efficiency and focal dimensions.
When neutral, two- and four-component efficiencies were [Formula: see text]% and [Formula: see text]%, respectively, spine flexion significantly increased four-component efficiency ([Formula: see text]%), but not two-component efficiency ([Formula: see text]%). Target-specific four-component re-configuration significantly improved efficiency ([Formula: see text]%). Both arrays produced controlled foci centered within the canal with similar 50% pressure contour dimensions: 10.8-11.9 mm (axial), 4.2-5.6 mm (lateral), and 5.9-6.2 mm (vertical). Simulation at 250 kHz also improved two- and four-component efficiency ([Formula: see text]% and [Formula: see text]%, respectively), but doubled the lateral focal dimensions.
Simulation shows that the spine-specific arrays are capable of producing controlled foci in the thoracic spinal canal.
The complex geometry of the human spine presents geometrical and acoustical challenges for transspine ultrasound focusing, and the design of these spine-specific ultrasound arrays is crucial to the clinical translation of focused ultrasound for the treatment of spinal cord disease.
设计并模拟两种特定于脊柱的相控阵在超声处理跨越胸椎的目标时的性能，目的是有效地在椎管内产生受控焦点。
使用多层射线声学模拟设计了两个阵列（每个 256 个元件，500 kHz）：一个具有专用元件的四分量阵列，用于通过椎旁和经椎间路径进行超声处理，以及一个具有脊柱特异性自适应聚焦的两分量阵列。使用中性和弯曲脊柱的正向模拟评估平均阵列效率（管腔焦点压力/水焦点压力），以研究减少脊柱引起的插入损耗的方法。测试了针对特定目标的四分量阵列重新配置和较低频率的超声处理（250 kHz），以确定它们对阵列效率和焦点尺寸的影响。
在中立时，两分量和四分量效率分别为[Formula: see text]%和[Formula: see text]%，脊柱弯曲显著增加了四分量效率（[Formula: see text]%），但不增加两分量效率（[Formula: see text]%）。针对特定目标的四分量重新配置显着提高了效率（[Formula: see text]%）。两个阵列都在管腔内产生了中心位于管腔内的受控焦点，具有相似的 50%压力轮廓尺寸：10.8-11.9 毫米（轴向）、4.2-5.6 毫米（侧向）和 5.9-6.2 毫米（垂直）。在 250 kHz 下进行的模拟还提高了两分量和四分量效率（分别为[Formula: see text]%和[Formula: see text]%），但使侧向焦点尺寸增加了一倍。
模拟表明，特定于脊柱的阵列能够在胸椎椎管内产生受控焦点。
人体脊柱的复杂几何形状给经脊柱超声聚焦带来了几何和声学挑战，这些脊柱特定超声阵列的设计对于聚焦超声治疗脊髓疾病的临床转化至关重要。
