Pilot Definity (perflutren lipid microspheres) CEUS microbubble perfusion/pressure imaging in STS RT

This single-site, open-label, non-randomized pilot at Thomas Jefferson University tests whether contrast-enhanced ultrasound (CEUS) can feasibly guide radiotherapy (RT) planning and predict response in patients with localized soft tissue sarcoma (STS) treated with neoadjuvant RT followed by surgery. The intervention is CEUS using Definity from Lantheus Medical Imaging, a microbubble ultrasound contrast agent (perflutren lipid microspheres) that enhances vascular perfusion signal; the imaging platform then quantifies tumor vascularity (contrast-enhanced area/volume vs total B-mode area/volume) and estimates tumor pressure via subharmonic signal analysis as a proxy for interstitial fluid pressure. Imaging is done three times (pre-RT, mid-RT, and post-RT/pre-op) and is paired with US–CT/MRI fusion using prior standard-of-care CT/MRI (or cone-beam CT) when feasible, otherwise performed side-by-side. Outcomes correlate these quantitative CEUS metrics with later size change and surgical pathology response. For localized STS, today’s care is limb-sparing surgery with perioperative external-beam RT (often pre-op) ± chemotherapy for select higher-risk histologies; this study’s angle is adding low-burden functional vascular/pressure readouts during RT to potentially identify responders earlier than anatomy-only imaging.