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Séminaire - Mickael Tanter Functional Ultrasound Imaging of Neuronal Activity

Abstract :

Functional imaging modalities such as fMRI or optical imaging identify regions of brain activity by measuring changes in blood flow thanks to the neurovascular coupling. Paradoxically, Ultrasound was not present in the field of Neuroscience till recently, whereas it is the most used modality for blood flow imaging in clinics. The reason for this was the poor sensitivity of Doppler ultrasound limiting blood flow imaging to large arteries. Ultrafast Doppler imaging based on plane wave imaging breaks this barrier and enabled recently the emergence of fUltrasound (by analogy to fMRI). fUltrasound (fUS) is able to provide unique whole brain images of perfusion on small rodents with unprecedented resolutions (100 µm and 10 ms). Functional imaging of cerebral blood volume during epileptic seizures, whisker or odor stimulations, drug injection emphasizes the potential of this new imaging modality to provide completely new information for the understanding of brain. As fUltrasound relies on ultrafast ultrasound acquisitions, it also enables the whole brain mapping of vascular indexes (such as resistivity, pulsatility or transient systolic time indexes) within a single cardiac cycle in addition to functional imaging of brain activity on longer time scales.

fUS is a great tool for neuroimaging on small animals as it already helps both to answer unsolved questions and image the functional activity of to date unexplored brain regions. It should become a a full-fledged imaging modality of neuroscience as it provides the first whole brain and portable neuroimaging modality for awake and freely moving animal studies. Beyond small animal imaging, clinical fUS should become an alternative to fMRI in particular applications, such as newborns or preterm infants both for neonatal seizure monitoring or cognitive science studies. It could also become a powerful portable tool for neuroimaging during peroperative surgery on adults.

Finally, we demonstrated recently that it can be combined with 3 µm diameter microbubbles injections in order to provide a first in vivo and non-invasive imaging modality at microscopic scales deep into organs (figure 2) combined with contrast agents by localizing the position of millions of microbubbles at ultrafast frame rates. This ultrasound localization microscopy technique solves for the first time the problem of in vivo imaging at microscopic scale the whole brain vasculature. Beyond fundamental neuroscience or stroke diagnosis, it will certainly provide new insights in the understanding of tumor angiogenesis.

Selected publications

Tanter M and Fink M. 
Ultrafast Imaging in Biomedical Ultrasound 
IEEE Transactions On Ultrasonics Ferroelectrics and Frequency Control, Jan. 2014

Mace, E.; Montaldo, G.; Cohen, I.; Baulac, M.; Fink, M. & Tanter, M., 'Functional ultrasound imaging of the brain', 
Nature Methods 8(8), 662--U85, 2011

B. Osmanski, S. Pezet, A. Ricobaraza, Z. Lenkei, M. Tanter 
Functional ultrasound imaging of intrinsic connectivity in the living rat brain with high spatiotemporal resolution
Nature Communications, October 2014

C. Errico, J. Pierre, S. Pezet, Y. Desailly, Z. Lenkei, O. Couture, M. Tanter 
Ultrafast ultrasound localization microscopy for deep in vivo super-resolution vascular imaging
Nature, September 2015.

L.-A. Sieu, Antoine Bergel, E. Tiran, T. Deffieux, M. Pernot, JL. Gennisson, M. Tanter, I. Cohen 
EEG and functional ultrasound imaging in mobile rats
Nature Methods, Sept. 2015

C. Demene, J. Baranger, M. Bernal, C. Delanoe, S. Auvin, V. Biran, M. Alison, J. Mairesse, E. Harribaud, M. Pernot, M. Tanter*, Olivier Baud* 
Functional ultrasound imaging of brain activity in human newborns
Science Translational Medicine, vol. 9, no. 411, p. eaah6756, Oct. 2017. 

Scientific focus :

Mickael Tanter is a research professor of the French National Institute for Health and Medical Research (Inserm) and distinguished professor of ESPCI Paris. He is heading the laboratory “Physics for Medicine” and deputy director of Langevin Institute (CNRS) at ESPCI, Paris, France.

He is also the director of the first INSERM Technology Research Accelerator created in 2016 and dedicated to Biomedical Ultrasound. Mickael Tanter is a world renowned expert in biomedical ultrasound and wave physics.
He authored more than 300 peer-reviewed papers and book chapters and is the recipient of 45 international patents. He co-invented several major innovations in Biomedical Ultrasound: Transient Elastography, Ultrafast Ultrasound and Shear Wave Elastography, functional Ultrasound imaging of brain activity and Ultrasound Localization Microscopy.

He received many national and international distinctions (among them the Honored Lecture of the Radiology Society of North America in 2012, the Grand Prize of Medicine and Medical Research of Paris city in 2011, the Grand Prize of Fondation de la Recherche Médicale in 2016 and the Carl Hellmuth Hertz Prize of IEEE Ultrasonics, Ferroelectrics and Frequency Control society in 2017).
M. Tanter is the co-founder of several MedTech companies in Biomedical Ultrasound (Supersonic Imagine, CardiaWave, Iconeus).