Professor Branca and her co-workers’ research titled Low-boiling Point Perfluorocarbon Nanodroplets as Dual-Phase Dual-Modality MR/US Contrast Agent is the subject of a cover story in the 24/2022 issue of ChemPhysChem magazine.
Ultrasound and Magnetic Resonance Imaging (MRI) are often combined to diagnose and treat cancer. These two techniques use very different contrast agents to enhance detection sensitivity. With MRI, the researchers generally use gadolinium-based or iron oxide-based contrast agents that affect the rate at which nuclear spins lose their phase coherence or relax back to their thermal equilibrium state after inducing perturbation of their state with radiofrequency waves. These contrast agents are generally safe, but some individuals may negatively react to them. With ultrasound, the team use microbubbles, a biocompatible gas-phase contrast agent that effectively scatters ultrasound waves. Low boiling point perfluorocarbons (LBPF) based microbubbles are a new class of ultrasound contrast agents. These are delivered to the body in a nanodroplet liquid form and can then be vaporized into microbubbles with localized acoustic energy. In addition to providing ultrasound contrast when converted into microbubbles, they can be used for targeted delivery of oxygen and drugs to specific tissues.
In this publication, in collaboration with Paul Dayton from BME, Professor Branca and her co-workers demonstrated that this new class of contrast agent can also be detected with MRI by using spin-polarized xenon and a combination of cleverly select radiofrequency pulses that enhance the sensitivity of MRI to both its ultrasound-invisible nanodroplet liquid form as well as its ultrasound visible microbubble form, effectively making them a dual-phase dual-modality contrast agent for MRI and US.