Abstract
Current therapy for space-occupying fetal lung mass lesions (fetal pulmonary lobectomy) is invasive and technically demanding. Accordingly, new therapeutic procedures are required which are much less invasive and more efficient. The purpose of this study was to investigate the feasibility of high-intensity focused ultrasound (HIFU) as a new therapeutic modality for fetal lung mass lesions, using an experimental animal model. We created a solid fetal lung model by differential lung ventilation using anesthetized adult rabbits. In this model, experimental animals with a unilateral independent (fluid-filled) lung were maintained by single lung ventilation of the other dependent lung. Within the independent lung, target blood vessels depicted by color flow Doppler were repeatedly irradiated with HIFU energy beams (n=19). Occlusion of these blood vessels in vivo was confirmed by evaluation of the flow using color flow Doppler. After the procedure, the animals were sacrificed and their harvested lungs were assessed grossly and microscopically. Pulmonary blood vessels (artery and/or vein) were effectively occluded with 2 to 5 cycles of HIFU energy delivery (10.5 seconds each) with a success rate of 62.5% (arteries) and 72.7% (veins). No clear changes including tissue perforations were observed grossly on the surface of the lungs. Ultrasound-guided HIFU energy delivery seems promising for occlusion of the pulmonary blood vessels within a fluid-filled independent lung (fetal lung model). Thus in the future, HIFU irradiation could be used as a less invasive technique to occlude the feeding vessels of fetal lung mass lesions in utero.
