Noninvasive Ureterocele Puncture Using Pulsed Focused Ultrasound: AnIn VitroStudy

Abstract

Purpose: To evaluate the feasibility of performing noninvasive puncture of pediatric ureteroceles with cavitation-based focused ultrasound (US) (histotripsy). Materials and Methods: A model for the ureterocele wall was developed from an excised bovine bladder wall. The model was exposed to focused US pulses in a water bath under three different US parameter sets for up to 300 seconds to create localized perforations in the wall. B-mode US imaging was used to monitor the treatment and assess potential imaging guidance and feedback. Results: Punctures were formed between 46-300 seconds, depending on the focused US exposure parameters and model wall thickness. Puncture diameter was controllable through choice of exposure parameters and could be varied between 0.8-2.8 mm mean diameter. US-induced cavitation was visible on B-mode imaging, which provided targeting and treatment feedback. Conclusions: Cavitation-based focused US can create punctures in a model that mimics the tissue properties of a ureterocele wall, under guidance from US imaging.

A Prototype Therapy System for Transcutaneous Application of Boiling Histotripsy

“…The histologic characteristics of histotripsy lesions are a homogenization of tissue structure on a subcellular level [15–17] and disorganization of tissue structures[18] without apparent thermal necrosis. Macroscopic effects include liquefaction of parenchymal tissue [19, 20] or erosion of tougher tissue structures [21, 22], often accompanied by minor bleeding into the lesion volume in an in vivo scenario [23, 24]. The boundaries of the lesions are usually well-defined; the inside of the volume displays complete homogenization, while just a few cell lengths away, tissue appears completely viable [15, 25].…”

Cavitation-induced pressure saturation: a mechanism governing bubble nucleation density in histotripsy

“…As a result, tissue can be homogenized into components at a subcellular level. Such an effect can be employed to liquefy blood clots from cardiovascular events (Maxwell et al 2009, Burgess et al 2012, destroy tumors (Vlaisavljevich et al 2013a, Vidal-Jove et al 2022, kill bacteria (Bigelow et al 2009, Childers et al 2021, Matula et al 2021, and structurally modify tissue to address congenital anomalies (Owens et al 2009, Maxwell et al 2014.…”