A laparoscopic HIFU probe for kidney ablation prior to partial nephrectomy

In an effort to reduce the complications associated with nephrectomy, high intensity focused ultrasound (HIFU) has been used to selectively ablate renal tissue prior to partial nephrectomy. To this end, a hand-held HIFU laparoscopic probe (OD=11 mm) was developed. The probe consists of two focused rectangular HIFU piezoceramic transducers for side and front firing configurations. The probe was fully characterized for electrical impedances, acoustic fields, and total acoustic power outputs for both side and front transducers. It was then tested in an in vivo animal experimental study in which 5 pigs were treated through a sterile HIFU open surgery procedure. A cross-sectional disk-shaped coagulative lesion was induced in the lower pole of the right kidney in each animal. The average treatment time for an ablated volume of 20cc was approximately 45 minutes. Histopathology results demonstrated contiguous well-delineated necrosed lesions extending from the kidney's pelvic system to the capsule. Moreover, the histology results suggested that the tissue ablation was obtained through both thermal and mechanical mechanisms. The overall results suggest that the cross-sectional necrosed tissue volume effectively reduces blood loss during partial nephrectomy.