  Ultrasound Localization Microscopy (ULM) relies on the injection of
microbubbles (MBs) to obtain highly resolved density maps of blood circulation
in vivo, with a resolution that can reach 10 {\mu}m ~ {\lambda}/10 in the
rodent brain. Static mean velocity maps can be extracted but are intrinsically
biased by potential significant changes in the number of MBs detected during
the cardiac cycle. Dynamic ULM (DULM) is a technique developed for non-invasive
pulsatility measurements in the brain of rodents, leading to temporally
resolved velocity and density cine-loops. It was previously based on external
triggers such as the electrocardiogram (ECG), limiting its use to datasets
acquired specifically for DULM applications while also increasing the required
acquisition time. This study presents a new motion matching method using tissue
Doppler that eliminates the need for ECG-gating in DULM experiments. DULM can
now be performed on any ULM datasets, recovering pertinent temporal
information, and improving the robustness of the mean velocity estimates.
