Feasibility study of pre-clinical Thiel embalmed human cadaver for MR-guided focused ultrasound of the spine

Background: Magnetic Resonance-guided Focused Ultrasound Surgery (MRgFUS) is a non-invasive treatment option based on high acoustic absorption and minimal thermal conductivity of the bone to destroy nerves and reduce pain. There is lack of a preclinical validation tool with correct human anatomy. This work introduces usage of an ex-vivo Thiel embalmed human tissue model for preclinical verification of MRgFUS on intervertebral discs or bone metastases within the spinal body.

Material and methods: Thiel embalmed human cadaver was subjected to FUS sonication of the vertebra (with energies 250J, 420J, 600J) and the intervertebral disc (with energies 310J, 610J, 950J) of the lumbar spine for 20s of sonication under MR guidance.

Results: For the vertebra, maximum temperatures were recorded as 38 °C, 58.3 °C, 69 °C. The intervertebral disc reached maximum temperatures of 23.7 °C, 54 °C, 83 °C. The temperature measurements showed that the spinal canal and adjacent organs were not heated > 0.1 °C.

Conclusions: A heating pattern that can induce thermal ablation was achieved in the vertebral body and the intervertebral disc. Adjacent structures and nerves were not heated in lethal levels. Thus, the Thiel embalmed human cadaver can be a safe and efficient model for preclinical study of application of MRgFUS on the upper lumbar spine.