福西 秀信¹, 高山 智子¹, 丸尾 猛¹, 松本 真一²

Hidenobu FUKUNISHI¹, Tomoko TAKAYAMA¹, Takeshi MARUO¹, Shinichi MATSUMOTO²

¹新須磨病院婦人科, ²新須磨病院放射線科

¹Shinsuma General Hospital, Department of Gynecology, ²Shinsuma General Hospital, Department of Radiology

キーワード : HIFU, MRgFUS, leiomyoma, focused ultrasound, low invasive

子宮筋腫の治療に関しては，子宮全摘出術が長きにわたり伝統的治療法であった．しかし，晩婚化が進む最近では，子宮温存を希望する女性が増加し，低侵襲の保存的治療への関心が高まっている．MRgFUS（MR-guided focused ultrasound surgery）による子宮筋腫治療は，メスを使わず，日帰り治療が可能で，日常生活への復帰が早いという利点があり，我国では2009年に薬事承認された．本治療に際しては，ExAblate 2000のテーブルに腹臥位になり，内蔵された208-エレメント・フェーズドアレイ トランスデューサーから発射される超音波が筋腫内に集束し，集束部分で60‐90℃となって筋腫組織が瞬時に熱凝固される．施療者は治療全工程にわたり細心の注意を払わなければならない．本法の治療効果は当院のアンケートでも70‐80％の患者満足度が得られており，筋腫の縮小や症状の改善，治療後の妊娠成立がみられている．しかし，治療中患者は腹臥位で不動の体位を数時間強いられること，超音波経路からの腸管排除に長時間を要することがあり，患者にとって不満の原因となる．治療後に十分な症状改善がみられず外科的治療を受ける例もあり，本治療適応症例の選択が重要である．重篤な有害事象はきわめて少なく，我国でも将来の挙児希望女性にMRgFUSの適応が広がるようデータを集積することが期待される．

Hysterectomy has been the traditional treatment for uterine leiomyoma; nowadays, however, many women opt for less invasive, uterus-preserving therapy. A new currently used technique, MR-guided focused ultrasound surgery (MRgFUS), is a less invasive procedure comprising real-time MR anatomic guidance, MR thermometry, and high-intensity focused ultrasound (HIFU). ExAbalte 2000 (InSightec, Israel) fully integrated with a 1.5T-MRI system (Signa, GE Healthcare, USA) was used in this study. Patients laid prone on the ExAblate table equipped with 208 beams from a phased-array transducer. The procedure, “scalpel-less surgery,” was carried out on an outpatient basis under conscious sedation, which required a short recovery time. About 75% of patients who underwent MRgFUS treatment in our hospital expressed satisfaction. Shrinkage of the leiomyoma and amelioration of symptoms were achieved 6 months after treatment, and pregnancies were achieved in several cases (despite current advice of contraindication). The system, ExAblate 2000, which was approved in 2009 in Japan for the treatment of uterine leiomyoma, entails very few and minor adverse events. Particular attention should be paid, however, to three major adverse events: skin burn, severe neuralgia, and intestine injury. The potential for improvements to MRgFUS includes shortening the duration of treatment, achieving a larger ablated volume, and placing the patient supine (a position requiring further studies on compression of vessels) on the ExAblate table. Another obstacle is extrusion of the bowel from the anterior of the uterus into the path of the ultrasound beam. In some cases, attempts at moving the bowel away from the ultrasound beam took 2 hours or even failed, resulting in the discontinuation of treatment. Our inquiries showed that 6 months after the treatment, about 2% of patients expressed regret at having undergone MRgFUS. Thus, patient selection before treatment with MRgFUS is important. It is expected after further study and worldwide trials that this technique may be applicable to those desiring fertility.