# Ultrasound and x-ray imageable poloxamer-based hydrogel for loco-regional therapy delivery in the liver

## TL;DR

A new injectable hydrogel visible under ultrasound and x-ray imaging is developed to improve targeted drug delivery to liver tumors.

## Contribution

A thermosensitive poloxamer-based hydrogel with imaging visibility under ultrasound and x-ray is developed for precise intratumoral drug delivery.

## Key findings

- Gel formulations with less than 1% microbubbles showed clear ultrasound visibility and minimal artifacts.
- Cross-sectional gel depositions were consistent between ultrasound and CT imaging in ex vivo and postmortem liver studies.
- The gel enables multimodal image-guided navigation, potentially improving drug delivery precision and workflow efficiency.

## Abstract

Intratumoral injections have the potential for enhanced cancer treatment efficacy while reducing costs and systemic exposure. However, intratumoral drug injections can result in substantial off-target leakage and are invisible under standard imaging modalities like ultrasound (US) and x-ray. A thermosensitive poloxamer-based gel for drug delivery was developed that is visible using x-ray imaging (computed tomography (CT), cone beam CT, fluoroscopy), as well as using US by means of integrating perfluorobutane-filled microbubbles (MBs). MBs content was optimized using tissue mimicking phantoms and ex vivo bovine livers. Gel formulations less than 1% MBs provided gel depositions that were clearly identifiable on US and distinguishable from tissue background and with minimal acoustic artifacts. The cross-sectional areas of gel depositions obtained with US and CT imaging were similar in studies using ex vivo bovine liver and postmortem in situ swine liver. The gel formulation enhanced multimodal image-guided navigation, enabling fusion of ultrasound and x-ray/CT imaging, which may enhance targeting, definition of spatial delivery, and overlap of tumor and gel. Although speculative, such a paradigm for intratumoral drug delivery might streamline clinical workflows, reduce radiation exposure by reliance on US, and boost the precision and accuracy of drug delivery targeting during procedures. Imageable gels may also provide enhanced temporal and spatial control of intratumoral conformal drug delivery.