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Sensing ultrasound localization microscopy for the visualization of glomeruli in living rats and humans
Louise Denis1, Sylvain Bodard2, Vincent Hingot1
1Sorbonne Université, CNRS, INSERM Laboratoire d'Imagerie Biomédicale, F-75006, Paris, France.
Background:
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 Localization Microscopy (ULM) has appeared. It is based on the ability to record continuous movements of individual microbubbles in the bloodstream. Although ULM improved the resolution of vascular imaging up to tenfold, the imaging of the smallest vessels had yet to be reported.
Methods:
We acquired ultrasound sequences from living humans and rats and then applied filters to divide the data set into slow-moving and fast-moving microbubbles. We performed a double tracking to highlight and characterize populations of microbubbles with singular behaviors. We decided to call this technique "sensing ULM" (sULM). We used post-mortem micro-CT for side-by-side confirmation in rats.
Findings:
In this study, we report the observation of microbubbles flowing in the glomeruli in living humans and rats. We present a set of analysis tools to extract quantitative information from individual microbubbles, such as remanence time or normalized distance.
Interpretation:
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.
Funding:
This study was funded by the European Research Council under the European Union Horizon H2020 program (ERC Consolidator grant agreement No 772786-ResolveStroke).
Insights
Researchers developed sensing Ultrasound Localization Microscopy (sULM) to visualize microbubbles in kidney glomeruli. This new imaging technique offers a direct method for assessing kidney function and diagnosing diseases.
Area of Science:
- Medical Imaging
- Nephrology
- Biomedical Engineering
Background:
- Glomerular function is crucial for diagnosing kidney diseases, but current clinical assessments rely on indirect blood and urine tests.
- Ultrasound Localization Microscopy (ULM) offers high-resolution vascular imaging but has not yet visualized the smallest vessels like glomeruli.
- Direct visualization of glomeruli could significantly advance kidney disease diagnosis and understanding.
Purpose of the Study:
- To develop and validate a novel ultrasound-based imaging technique for visualizing microbubble flow within the glomeruli of living subjects.
- To establish methods for analyzing microbubble behavior to extract quantitative functional information from the glomeruli.
Main Methods:
- Acquired ultrasound sequences from living humans and rats.
- Applied advanced filtering to differentiate microbubble populations based on movement.
- Developed a double-tracking analysis to characterize individual microbubble behavior, termed sensing ULM (sULM).
- Validated findings using post-mortem micro-CT in rats.
Main Results:
- Successfully observed microbubbles flowing within the glomeruli of both living humans and rats.
- Developed analysis tools to quantify individual microbubble dynamics, including remanence time and normalized distance.
- Demonstrated the capability of sULM to image microvascular flow in the kidney's functional units.
Conclusions:
- Direct visualization of glomeruli using sULM can deepen the understanding of kidney function and disease.
- This technique holds potential as a diagnostic tool for kidney diseases in clinical settings.
- sULM advances imaging capabilities towards the functional units of organs, crucial for understanding various diseases.
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