Microbubble tracking with a forward-backward strategy

Iman Taghavi*, Sofie Bech Andersen, Mikkel Schou, Michael Bachmann Nielsen, Charlotte Mehlin Sorensen, Matthias Bo Stuart, Jorgen Arendt Jensen

*Corresponding author for this work
4 Citations (Scopus)


Microbubble (MB) tracking is an integral part of super-resolution ultrasound imaging by providing sharper images and enabling velocity estimation. Tracking the MBs from the last to the first frame can generate different trajectories than tracking from the first to the last frame, when the next positions of a track depends on its previous positions, e.g., in Kalman-based methods. Our hypothesis is that tracking in a forward-backward manner can increase the overall tracking performance. In simulations, MB positions with a parabolic flow profile were generated inside two tubes. Three different tracking methods, including nearest-neighbor, Kalman, and hierarchical Kalman, were investigated. Using the proposed forward-backward strategy, all estimated velocity profiles for all trackers were improved and were closer to the actual velocity profiles with an improvement between 28% to 40% in the relative standard deviation (RSD) of the velocity values over 10 cross-sections of the tubes. A Sprague Dawley rat kidney was scanned for 10 minutes using a BK5000 scanner and X18L5s transducer, which is a linear array probe with 150 elements. The tracking results from the in vivo experiments showed that the combined image of the forward and backward tracks had 35% additional unique track positions. It showed a clear visual enhancement in the super-resolved velocity map. Overall, the improvement in visual aspects and velocity estimates suggest forward-backward strategy as an upgrade for Kalman-based trackers.

Original languageEnglish
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Publication statusPublished - 2022
EventMedical Imaging 2022: Ultrasonic Imaging and Tomography - Virtual, Online
Duration: 21 Mar 202227 Mar 2022


ConferenceMedical Imaging 2022: Ultrasonic Imaging and Tomography
CityVirtual, Online
SponsorThe Society of Photo-Optical Instrumentation Engineers (SPIE)


  • Particle tracking
  • Super-resolution imaging
  • ultrasound microscopy
  • velocity estimation


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