Short Opinion - (2021) Volume 10, Issue 2
The design and simulation of the performance of two phased spine-specific arrays in sonic targets spanning the thoracic spine with the goal of generating controlled foci in the spinal canal effectively. Using multi-layered ray acoustics simulation, two arrays (256 elements each, 500 kHz) were created: a fourcomponent array with dedicated components for sonicating through the paravertebral and transvertebral paths, and a twocomponent array with spine-specific adaptive focusing. Using forward simulation in neutral and flexed spines to explore methods that minimise spine-induced insertion failure, mean array efficiency (canal focus pressure/water focus pressure) was assessed. The effects of target-specific four-component array reconfiguration and lower frequency sonication (250 kHz) on array efficiency and focal measurements were investigated.
When the two- and four-component efficiencies were [Formula: see text] percent and [Formula: see text] percent, respectively, spine flexion improved four-component efficiency ([Formula: see text] percent), but not two-component efficiency ([Formula: see text] percent). ([Formula: see text] percent). The efficiency of a target-specific four-component re-configuration was dramatically improved ([Formula: see text] percent. Both arrays developed managed foci centred inside the canal with 50 percent pressure contour measurements of 10.8-11.9 mm (axial), 4.2-5.6 mm (lateral), and 5.9-6.2 mm, respectively (vertical).
However, simulation at 250 kHz doubled the lateral focal dimensions while improving two- and four-component efficiency ([Formula: see text] percent and [Formula: see text] percent, respectively). Simulation shows that in the thoracic spinal canal, the spinespecific arrays are able to generate controlled focal points.
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.