IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Dec;65(12):2322-2331. doi: 10.1109/TUFFC.2018.2872171. Epub 2018 Sep 26.
Focused ultrasound has been shown to increase the permeability of the blood-brain barrier and its feasibility for opening the blood-spinal cord barrier has also been demonstrated in small animal models, with great potential to impact the treatment of spinal cord (SC) disorders. For clinical translation, challenges to transvertebral focusing of ultrasound energy on the human spinal canal, such as a focal depth of field and standing-wave formation, must be addressed. A dual-aperture approach using multifrequency and phase-shift keying (PSK) strategies for achieving a controlled focus in human thoracic vertebrae was investigated through numerical simulations and benchtop experiments in ex vivo human vertebrae. An ~85% reduction in the focal depth of field was achieved compared to a single-aperture approach at 564 kHz. Short-burst (two-cycle) excitations in combination with PSK were found to suppress the formation of standing waves in ex vivo human thoracic vertebrae when focusing through the vertebral laminae. The results make an important contribution toward the development of a clinical-scale approach for targeting ultrasound therapy to the SC.
聚焦超声已被证明可以增加血脑屏障的通透性，其在小动物模型中打开血脊髓屏障的可行性也已得到证实，这对脊髓（SC）疾病的治疗具有重大影响。为了实现临床转化，必须解决将超声能量经椎间孔聚焦于人体椎管的问题，例如焦深和驻波的形成。本研究通过数值模拟和离体人椎骨的台架实验，探索了使用多频和相移键控（PSK）策略的双孔径方法，以实现人胸椎的可控焦点。与 564 kHz 的单孔径方法相比，焦深减少了约 85%。在通过椎板聚焦时，发现短脉冲（两周期）激发与 PSK 相结合可以抑制离体人胸椎中驻波的形成。这些结果为开发针对 SC 的临床规模靶向超声治疗方法做出了重要贡献。
