Development and preclinical testing of a novel biodegradable hydrogel vaginal packing technology for gynecologic high-dose-rate brachytherapy

Purpose: We evaluated the performance of a novel hydrogel-based strategy developed for clinical use as vaginal packing using phantoms and cadavers, and to compare the hydrogel to gauze and balloon packing. Material and methods: The biocompatible hydrogel is based on a thiol-Michael addition reaction, with delivery of reagents into the vaginal cavity using a custom-made system. Soft-cured cadavers were used for soft tissue-like mechanical properties. Two cadavers with intact uteri had magnetic resonance imaging (MRI) compatible with tandem and ovoids. For one cadaver, the temperature of the vaginal canal was measured before hydrogel application, during polymerization, and after hydrogel removal. The hydrogel packing and applicator was kept in a second cadaver, which was imaged using computed tomography (CT) and MRI. The hydrogel packing and imaging was repeated for an open multichannel MRI compatible, titanium-based vaginal cylinder placed in a post-hysterectomy cadaver. Results: The gel reaction occurred within 90 seconds, indicating polymerization at clinical quantities with a 5°C increase in vaginal temperature. CT and MRI imaging identified the hydrogel readily and showed a conformance to anatomy with few air pockets. The entire hydrogel packing was readily retrieved upon completion of imaging. Conclusions: The novel strategy for polyethylene glycol (PEG)-based hydrogel intra-vaginal packing was able to rapidly polymerize in human cadavers with minimal heat production. Delivery was efficient and able to fill the contours of the vaginal cavity and displace tissue away from the applicator axis. The hydrogel has favorable imaging characteristics on CT and MRI, and shows a potential for clinical use, warranting additional studies for the use in humans.