Towards sub-100Hz Super-Resolution Imaging Through a Novel Bi-Directional Interpolation Technique

Ultrasound Localization Microscopy (ULM) represents a safe, non-invasive and low-cost imaging modality for visualization of the microcirculation at clinically relevant depth. In fact, by precisely localizing and tracking microbubbles (MBs) injected in the circulation, ULM characterizes the microsvascular structures. However, ULM is currently constrained to high frame rates necessary to accurately track MBs in two successive frames (kHz-range). Such high frame rates are generally beyond the reach of clinical scanners (sub-100 Hz). Here, we suggest acquiring the data at a lower frame rate followed by applying a reconstruction technique to compensate for the lost information due to the low frame rate imaging. We introduce a novel 2x2D interpolation using radial basis function (RBF)-based reconstruction to estimate unknown values in the 3D In-phase and Quadrature (IQ) data (x-z-t), thereby enhancing temporal resolution. This bidirectional approach improves the reconstruction of MBs’ dynamics by interpolating along both x and z directions. The method was tested on a rat brain data demonstrating relaxing the frame rate to 100 Hz while maintaining image quality comparable to the original high frame rate data.