Abstract
In general, fetuses with sacrococcygeal teratoma (SCT) are at risk of high output cardiac failure with hydrops. The aim of this study was to evaluate feasibility of high-intensity focused ultrasound (HIFU) for minimally invasive treatment of fetal SCT. HIFU is an acoustic technique that utilizes the ultrasound power to exclusively thermocoagulate target tissues without damaging its overlying and underlying organs or tissues.
In our study, all animal experiments were conducted under general anesthesia using a specifically designed transducer (4.44 MHz, 38 mm in diameter, focal distance of 42 mm). With the use of five Japanese white rabbits, three intrarenal arterial branches were targeted and coagulated (day 0). Each HIFU procedure was performed underwater (in saline) after freely mobilizing the left kidney (with its vascular pedicle) from surgically exposed retroperitoneal space. Likewise, on postoperative day 7 and 14, the intrarenal arterial branches underwent HIFU irradiation. Before and after each HIFU procedure, flow velocity of the hilar renal artery was measured using color flow Doppler. These experimental animals were sacrificed on postoperative day 28. Immediately after sacrifice, each harvested kidney was grossly inspected and weighed with the following histological examination of the irradiated (left) as well as non-irradiated (right) kidneys. In all five experimental animals, renal arterial flow velocity soon decreased after HIFU procedures and in four, the irradiated kidney weighed significantly less as compared with each contralateral kidney. In summary, HIFU irradiation successfully reduced blood flow of the targeted renal arteries. Thus, HIFU is expected to be useful for occluding feeding blood vessels of the tissues. In conclusion, HIFU irradiation is likely to become an effective and minimally invasive means of treating intraamniotic fetal tumors.
