Speaker: Mr. Vincent Hingot

Time and Date: 9:00-11:00 am, October 26, 2018

Place: Room 423 of Scientific Building, Handan Campus,Fudan University

Abstract:

By localizing the acoustic signature of individual microbubbles in the vasculature, Ultrasound Localization Microscopy (ULM) surpasses the diffraction-limit by orders of magnitude and reaches microscopic resolution. In Errico et al, Nature 2015, ULM achieved resolution of 8 μm over a depth of 12 mm in the rat brain. However, to reach such a microscopic resolution, more than one million microbubbles had to be individually localized and tracked for three minutes, highlighting the fundamental trade-off between temporal and spatial resolutions. Significant progress has been made in image processing strategies to correct motion induced artifacts, to increase localization precision and to reduce computation time. However, because of its intrinsic link with the vasculature, ULM still faces an incompressible compromise between the injected microbubble dose, the acquisition time and the spatial resolution.
ULM was performed to image the cerebral microvasculature in rats. Six million microbubbles were localized with a precision of 5 μm. Saturation curves were obtained for images with pixel sizes ranging from 5 μm to 100 μm. Additionally, a detailed time analysis of the reconstruction was performed in 150 individualized vessels. We show that, while 90μm vessels are reconstructed in seconds, it takes several minutes to map the vessels at the scale of the capillaries (5 μm).
The fundamental limit of spatial resolution is determined through a model linking the necessary acquisition time with the microbubble’s concentration, the pixel size and the size of the vessels to reconstruct. This model should help to understand both capabilities and limitations of ULM for the description of the microvasculature.

Biography:

Vincent Hingot graduated from ESPCI in 2016, a French engineering school located in Paris, majoring in engineering technologies for health. He started a PhD in Institute Langevin shortly after to work on medical ultrasounds with Mickael Tanter and Olivier Couture. Following the work of Claudia Errico and Marine Bezagu, he worked on exploiting different interactions between ultrasound and contrast agents for imaging and therapy. He focused mainly on the development of ultrafast Ultrasound Localization Microscopy (ULM) and its application to in vivo study of different vascular pathologies, together with the development of new techniques for ultrasound mediated drug delivery and its application to the delivery of anti-cancerous agents.