(5)強出力集束超音波(HIFU)を用いた栄養血管閉塞による子宮筋腫の低侵襲治療(<特集>第59回シンポジウム1「子宮筋腫の発育制御とその管理」)

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The final goal of our study is to develop the non-invasive therapy for uterine fibroid by feeding vessels occlusion using high intensity focused ultrasound(HIFU). As a step for the goal, following basic studies have been conducted. 1) Measurement of blood flow to uterine fibroid ; A micro bubble solution, Levovist[○!R], was administrated to the patient of uterine fibroid. Increases in the intensity of signal from the tissue were measured by pulsing interval times (0.5,1,3,5seconds) and blood flow indices were calculated. The indices of tissue blood flow of uterine fibroids were compared with those of the myometrium. The result showed lower tissue blood flow to uterine fibroid than myometrium. 2) Animal experiments for artery occlusion ; HIFU was sonicated to deep femoral arteries of Sprague Dawley rats. Duration of sonication was 5seconds. Blood flow occlusion was accomplished by HIFU sonication at 4,300W/cm^2, but the flow was preserved with intensities at 530, 1,080 and 2,750W/cm^2. Peak systolic velocity of blood flow increased in sonicated arteries with HIFU at 1,080 and 2,750W/cm^2 and correlated with HIFU intensity. Histological studies have demonstrated vacuolar degeneration in tunica media of the vessels exposed to HIFU at 2,750 and 4,300W/cm^2. Injecting ultrasound contrast agents (Levovist[○!R]) decreased the HIFU intensity required for arterial occlusion, because microbubbles were destroyed under ultrasound sonication and exerted a cavitation effect on the vessel endothelium, which would damage blood vessels. 3) Reducing effect of tumor by occlusion of the tumor-feeding artery ; VX2(dermatological squamous cancer cell) was implanted in the right femoral muscles of Japanese White rabbits. After 3 weeks, animals were provided to experiment of HIFU sonication to feeding arteries (Peak intensity ; 4kW/cm^2). In the control group, the tumor volume increased significantly in comparison with before HIFU sonication. On the other hand, in the study group, the tumor volume showed a tendency to increase, but the significance was not recognized. HE staining revealed vacuolar degeneration in the tunica media of the artery and degenerative necrosis in the tumor. 4) Occlusion of the human uterine fibroid feeding artery ; A total of 6 patients with uterine fibroids, who had been scheduled for hysterectomy were enrolled in this study. HIFU was applied after laparotomy. Peak intensities were 2(n=4) and 4(n=5)kW/cm^2. In those fibroid arteries to which HIFU had been applied at 2kW/cm^2, the HE stain revealed a vacuolar degeneration in the tunica media of the artery, although cessation of blood flow was not accomplished. The uterine fibroids artery could be successfully occluded by HIFU at 4kW/cm^2 in two cases out of five. In these cases, the HE stain revealed strong vacuolar degeneration in the tunica media and collapsed cavity. It has been demonstrated by our study that HIFU sonication can achieve the occlusion of deep arteries. Additionally to this fact, low tissue blood flow to uterine fibroid also support that, occlusion of tumors' feeding arteries by HIFU may be an option for non-invasive therapy for uterine fibroid.
社団法人日本産科婦人科学会の論文
2007-09-01

(5)強出力集束超音波(HIFU)を用いた栄養血管閉塞による子宮筋腫の低侵襲治療(<特集>第59回シンポジウム1「子宮筋腫の発育制御とその管理」)

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