川﨑 元敬¹, 南場 寛文¹, 泉 仁¹, 武政 龍一¹, 池内 昌彦¹, 牛田 享宏²

Motohiro KAWASAKI¹, Hirofumi NAMBA¹, Masashi IZUMI¹, Ryuichi TAKEMASA¹, Masahiko IKEUCHI¹, Takahiro USHIDA²

¹高知大学医学部整形外科, ²愛知医科大学学際的痛みセンター

¹Department of Orthopaedic Surgery, Kochi University, Kochi Medical School, ²Multidisciplinary Pain Center, Aichi Medical University

キーワード :

【Introduction】
Magnetic resonance-guided focused ultrasound（MRgFUS）treatment is a novel and innovative therapeutic procedure that achieves non-invasive thermal denaturation by focusing many ultrasound waves on a target tissue. The MR guidance allows an identification of the accurate position of the target lesion and a real time monitoring of the temperature on the surface of the target bone lesion and the adjacent anatomical structures, using the proton resonance frequency（PRF）shift method. In recent years, we have undertaken clinical researches on using the MRgFUS treatment for the management of bone metastatic pain and chronic osteoarthritic pain. The purpose of this retrospective study was to evaluate the characteristics of a real-time temperature monitoring during the treatment and changes in MR images immediately after the treatment.
【Patients and Methods】
After giving their informed consents, 12 patients with painful bone metastasis and 26 patients with chronic pain produced by lumbar facet joint osteoarthritis and knee osteoarthritis underwent MRgFUS treatment, using the ExAblate^®system（InSightec）integrated into the patient table of a 3.0-tesla MRI scanner. The targeted treatment areas were bone metastatic lesions and periarticular areas inducing a refractory pain. In the treatment of bone metastasis and degenerative osteoarthritis, the target temperatures on the irradiated bone lesions were more than 60℃and more than 55℃respectively while obtaining a real-time thermal feedback. After the procedure, gadolinium-enhanced MR images for bone metastasis and fat suppressed images for degenerative osteoarthritis were performed in order to evaluate the ablated area.
【Results】
In a real-time temperature monitoring during a sonication, we confirmed the target temperature rise was reached relatively easily by adjusting the sonication power. In most patients, the temperatures that rose at the targeted bone surface were maintained for several seconds after the sonication. MR images acquired immediately after the treatment demonstrated necrosis of the ablated area within the lesion in most of the patients with bone metastasis and thermal denaturation of the targeted joint surface in all of the patients with lumbar facet joint osteoarthritis.
【Conclusion】
The MRI monitoring in the focused ultrasound treatment for the bone and joint diseases and the MRI evaluation before and after the procedures were effective to achieve the safe and accurate thermal denaturation of the target organization.