Application of high-intensity focused ultrasound for fetal therapy: experimental study using an animal model of lower urinary tract obstruction.

Abstract

The purpose of this study is to investigate whether high-intensity focused ultrasound (HIFU) exposure is able to produce a fistula between the bladder and abdominal wall of a fetus with lower urinary tract obstruction (LUTO). We constructed a prototype HIFU transducer in combination with an imaging probe. HIFU was applied to the lower abdomen of a rabbit neonate that was complicated by LUTO as an experimental model to produce a fistula; HIFU was applied in a tank filled with degassed water. Exposed lesions were assessed by histological analysis at necropsy. When HIFU was applied at 5.5kW/cm(2) of spatial-peak temporal average intensity (SPTA), a fistula was created between the lower abdominal wall and the urinary bladder; urine gushed out from the bladder through the fistula within 60s after HIFU exposure. The findings suggest that fetal diseases such as LUTO can be non-invasively treated using HIFU exposure from even outside the maternal body, though this study was performed in a water tank.