高强度聚焦超声对离体兔腰椎间盘的生物学效应

目的观察不同剂量高强度聚焦超声对兔离体腰椎间盘的生物学效应。方法取6例剥离软组织的兔腰骶段脊柱标本（L1～S1）。将频率为9.6MHz、脉冲1 000Hz、剂量5W、焦距4mm的高强度聚焦超声从正前方聚焦于6例脊柱的L1S1椎间盘,各持续3、6、9、12、15、18min。此过程中,用热电偶针监测前方纤维环处与髓核交界处、HIFU焦点处、后方纤维环与髓核交界处、椎管内脊髓前表面的温度。结果 HIFU辐照过程中,监测点的温度逐渐升高,但升高的速度逐渐下降。HIFU在椎间盘前、后方纤维环处都能提供50℃以上的高温,并持续6min以上;焦点处能提供80℃以上的高温,并持续6min以上。结论高强度聚焦超声在椎间盘纤维环内可以提供足够高的温度,灭活纤维环内神经感受器可使髓核溶解、变性、萎缩,是治疗椎间盘源性腰痛的潜在方法。

Biological Effects of High-intensity Focused Ultrasound on Rabbit Lumbar Intervertebral Discs In Vitro

Objective To observe biological effects of different doses of high intensity focused ultrasound(HIFU)on the rabbit lumbar intervertebral discs in vitro.Methods Six specimens of rabbit lumbar spine of L1 to S1 with strip of soft tissue are involved.Ultrasound with frequency of 9.6 MHz,pulse of 1000 Hz,acoustic power of 5w and focal length of 4 mm was produced by CZF Focused Ultrasound Surgery System.Ultrasound sonication are carried out from front of intervertebral disc L1 to S1 of six specimens,respectively lasting 3 min,6 min,9 min,12 min,15 min,18 min.Meanwhile,thermocouple measurements were made from four positions:anterior annulus fibrosus at the junction with nucleus pulposus,HIFU focal point,posterior annulus fibrosus at the junction with nucleus pulposus and anterior surface of spinal cord.Results During ultrasound sonication,the temperatue of target zones showed a gradual increase with a decreased rate of increase.HIFU can provide more than 50 ℃ at either anterior or posterior annulus fibrosus for 6 minutes or more,and provide more than 80 ℃ at focal point.Conclusion HIFU can provide high enough temperature to achieve inactivation of nerve receptors within the annulus fibrosus and degeneration and atrophy of nucleus pulposus,therefore,HIFU is a potential treatment method for discogenic low back pain.