 Polyphosphoester polymers are a new class of biomaterials with potential applications in drug delivery and tissue regeneration. These polymers have been modified to contain 31p centres, which allow them to be used as MI traces. The polymers were designed to have improved MI relaxation times, allowing for background free imaging and biodegradability. Additionally, they can be used to deliver drugs, such as protac, which can be used for theranostics. This study demonstrates the potential of polyphosphoesters as MI traceable polymers for theranostic applications. This article was authored by Olga Koskina, Timo Reinberger, Vera Flock and others.