What is functional ultrasound imaging ?
Functional ultrasound imaging is a high-sensitivity, high-spatial & high-temporal resolution imaging modality of brain activity and cerebro-vascular flows. Functional ultrasound imaging allows the mapping of very small variations of cerebral blood volume thanks to dedicated ultra-high sensitivity sequences and optimized hardware. This revolutionary technology is based on ultra-high-sensitivity ultrasound imaging using multi-plane wave transmissions at thousands of frames per second.
Functional ultrasound imaging offers a large range of applications including:
Mapping blood vessels and their blood volume variations at high-sensitivity and spatio-temporal resolution
Task-based functional imaging (such as in fMRI)
Pharmacalogically-induced blood volume variations (such as in PhMRI)
Unsupervised functional imaging for awake animals
Imaging of functional brain connectivity (such as in resting-state fMRI)
What is the story of functional brain ultrasound and Iconeus ?
Functional ultrasound imaging relies on ultra high sensitivity Doppler imaging based on plane-wave acquisitions that was pioneered by our co-founder and academic scientific partner Prof. Mickael Tanter at the Langevin Institute (ESPCI/CNRS/INSERM), Paris, France. Very-high-frame rate imaging radically improved Doppler imaging sensitivity and led to a breakthrough neurofunctional imaging modality, as first published in Nature Methods in 2011. Since then, continuous innovations leveraged the technology from the physics bench to a high-end, plug-and-play technology for neuroscientists.
For more details, please visit the website of Prof. Mickael Tanter, head of the lab that invented functional brain ultrasound imaging:
What is measured by functional ultrasound imaging ?
Functional ultrasound imaging uses ultra-high sensitivity power Doppler sequences to estimate the blood volume in small vessels.
It has been shown that the power Doppler signal is directly proportional to cerebral blood volume (CBV).
Thanks to this direct link with CBV, functional ultrasound imaging can measure cerebral activity with CBV increases between 10 and 50% during stimulations, a variation much larger than can be measured with BOLD imaging in fMRI.
What is the spatiotemporal resolution of functional ultrasound imaging ?
Our system uses a high-frequency transducer at 15MHz that provides in-plane spatial resolution of 100µm with a 400 µm slice width.
The temporal resolution of the raw ultrasound images is around 50 microseconds.
The temporal resolution of the cerebral blood volume images is between 50 milliseconds and 1 second and can be adapted in accordance with the study, physiology and required sensitivity.
In rodents, fUS imaging of brain activity typically has a 100×100 micrometer in-plane spatial resolution and one cardiac cycle (200-millisecond temporal resolution in mice, 300 milliseconds in rats).
What is the sensitivity of functional ultrasound imaging ?
Iconeus technologies allow to achieve a sensitivity hundred times higher than that of other commercial preclinical ultrasound systems.
Iconeus ultra-high sensitivity to cerebral blood volume changes is the specific scientific base that allows functional ultrasound imaging with deep penetration capabilities leading to whole brain imaging.
How long does a typical aquisition take?
The duration of an acquisition ranges from several seconds to several hours, depending on the physiological phenomenon that is being observed.
Typically, task-based functional ultrasound imaging requires between 30 seconds and 5 minutes depending on the stimulus pattern used.
Connectivity matrix construction requires between 5 and 10 minutes in anesthesized specimens and between 10 and 30 minutes in awake specimens.
Acquisition duration can continue for many hours, limited only by the internal hard-drive storage capacity. If you need a specific configuration for your setup, please contact Iconeus. Our versatile technology offers a host of options.
What is the difference between this and other commercial ultrasound systems ?
Unlike conventional ultrasound imaging, which uses step-wise scanning with focused sound waves, functional ultrasound imaging is conceptually different since it relies on multi-plane wave transmissions at thousands of frames per second. Your department or company may have already access to, or be planning to purchase a traditional ultrasound system. However, those machines cannot be used, or upgraded to be used, for functional ultrasound imaging.
The Iconeus platform relies on a unique patented technology. Our dedicated hardware and software allows the acquiring and processing of huge amounts of data which ensures our unique, ultra-high sensitivity.
We invite you to compare blood vessel images produced by Iconeus (or by prototype systems of our founder's labs) with images generated by any other conventional ultrasound systems in order to fully appreciate the technological advantage we offer!