Increasing Microbubble Concentrations in Microvascular Imaging via Microbubble Separation by means of Orthogonal Frequency Division Multiplexing

Ultrasound Localization Microscopy (ULM) is a medical imaging modality enabling ultrasound to resolve mi-crovascular structures at clinically relevant depths. The microscopic resolution of ULM-generated images is ensured by the precise localization and tracking of injected ultrasound microbubbles (MBs). However, precise MBs’ localization relies on the presence of isolated MBs signals, which practically translates into a low MBs concentration constraint. Considering this constraint and the low perfusion in small vessels, ULM’s time for micro-vessels imaging substantially elongates. Such long acquisition times are not practical in the clinical context and are contributing to slowing ULM’s clinical transition. To overcome the limit on low MBs concentrations, we introduce two monodisperse MB populations, which are separable through Orthogonal Frequency Division Multiplexing (OFDM). Results in a flow channel phantom demonstrate the feasibility of uncoupling the two MB populations. Thus, the proposed approach might alleviate the requirement of low MBs concentration, ultimately allowing for faster microvascular imaging.