Sensing Ultrasound Localisation Microscopy for the visualisation of glomeruli in living humans
Author Block: S. Bodard; Paris/FR
Purpose: Estimation of glomerular function is necessary to diagnose kidney diseases. However, the study of glomeruli in the clinic is currently done indirectly through urine and blood tests. A recent imaging technique called Ultrasound Localisation Microscopy (ULM) has appeared. It is based on the ability to record continuous movements of individual microbubbles in the bloodstream. The aim of this study was to use ULM for glomeruli visualisation. Although ULM improved the resolution of vascular imaging up to tenfold, the imaging of the smallest vessels had yet to be reported.
Methods or Background: We acquired ultrasound sequences from living humans and then applied filters to divide the data set into slow-moving and fast-moving microbubbles. We performed a double tracking to highlight and characterise populations of microbubbles with singular behaviours. We decided to call this technique “sensing ULM” (sULM).
Results or Findings: In this study, we report the observation of microbubbles flowing in the glomeruli in living humans. We present a set of analysis tools to extract quantitative information from individual microbubbles, such as remanence time or normalised distance.
Conclusion: As glomeruli play a key role in kidney function, it would be possible that their observation yields a deeper understanding of the kidney. It could also be a tool to diagnose kidney diseases in patients. More generally, it will bring imaging capabilities closer to the functional units of organs, which is a key to understand most diseases, such as cancer, diabetes, or kidney failures.
Limitations: The spatial resolution of CEUS, i.e. between 70 and 150 μm, the localisation error of 43±4 μm - that increases with depth due to divergent ultrasound beam - and the presence of efferent and afferent arterioles in the same track as glomeruli leaded us to a rough PDW estimation with sULM
Funding for this study: This study was funded by the European Research Council under the European Union Horizon H2020 program (ERC Consolidator grant agreement No 772786-ResolveStroke).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The Ethics Committee of the French Society of Radiology approved this study (CERF, reference number CRM-2203-240).