Fiber optic ultrasonic imaging probe for future nanoscale disease diagnostics – sciencedaily

Scientists at the University of Nottingham have developed an ultrasound imaging system, which can be deployed on the tip of a very fine optical fiber and which will be insertable into the human body to visualize cellular abnormalities in 3D.

The new technology produces microscopic and nanoscopic resolution images that will one day help clinicians examine cells in hard-to-reach parts of the body, such as the gastrointestinal tract, and provide more effective diagnostics for diseases ranging from cancer gastric bacterial meningitis.

The high level of performance that the technology offers is currently only possible in cutting-edge research laboratories with large scientific instruments – while this compact system has the potential to integrate it into clinical environments to improve patient care. patients.

The innovation funded by the Engineering and Physical Sciences Research Council (EPSRC) also reduces the need for conventional fluorescent labels – chemicals used to examine cell biology under a microscope – which can be harmful to human cells in high doses.

The results are reported in a new article entitled “ Phonon imaging in 3D with a fiber probe ” published in the journal Nature, Light: science and applications.

The author of the article, Salvatore La Cavera, EPSRC Doctoral Fellow from the University of Nottingham Optics and Photonics Research Group, said of the ultrasound imaging system: “We believe it is capable to measure the stiffness of a specimen, its biocompatibility and its The endoscopic potential, while reaching the nanoscale, is what sets it apart.These characteristics prepare the technology for future measurements inside the body; towards the ultimate goal of minimally invasive point-of-care diagnostics. “

Currently at the prototype stage, the non-invasive imaging tool, described by researchers as a “phonon probe”, is capable of being inserted into a standard optical endoscope, which is a thin tube with powerful light and a camera. in the end that is have navigated the body to find, analyze and operate on cancerous lesions, among many other diseases. The combination of optical and phonon technologies could be advantageous; speed up the clinical workflow process and reduce the number of invasive test procedures for patients.

3D mapping capabilities

Just as a doctor can perform a physical exam to detect abnormal “stiffness” in the tissue under the skin that could indicate tumors, the phonon probe will bring this concept of “3D mapping” to the cellular level.

By scanning the ultrasonic probe in space, it can reproduce a three-dimensional map of the stiffness and spatial characteristics of microscopic structures at and below the surface of a specimen (eg tissue); it does so with the power to imagine small objects like a large-scale microscope, and the contrast to differentiate objects like an ultrasound probe.

“Techniques capable of measuring whether a tumor cell is rigid have been performed with laboratory microscopes, but these powerful tools are bulky, immobile, and unsuitable for the clinical settings of patients. Nanoscale ultrasound technology in endoscopic capacity is about to take that leap, ”added Salvatore La Cavera.

How it works

The new ultrasound imaging system uses two lasers that emit short pulses of energy to stimulate and detect vibrations in a sample. One of the laser pulses is absorbed by a layer of metal – a nano-transducer (which works by converting energy from one form to another) – made at the end of the fiber; a process that causes high frequency phonons (sound particles) to be pumped into the sample. Then a second laser pulse collides with the sound waves, a process known as Brillouin scattering. By detecting these “colliding” laser pulses, the shape of the traveling sound wave can be recreated and displayed visually.

The detected sound wave encodes information about the stiffness of a material, and even its geometry. The Nottingham team were the first to demonstrate this dual capability using pulsed lasers and fiber optics.

The power of an imaging device is usually measured by the smallest object visible to the system, that is, the resolution. In two dimensions, the phonon probe can “resolve” objects of the order of 1 micrometer, such as a microscope; but in the third dimension (height), it provides measurements at the nanometer scale, which is unprecedented for a fiber optic imaging system.

Future applications

In the article, the researchers demonstrate that the technology is compatible with both a single optical fiber and the 10-20,000 fibers of an imaging bundle (1mm in diameter), as used in conventional endoscopes. .

Therefore, higher spatial resolution and wide fields of view could be systematically obtained by collecting stiffness and space information from several different points on a sample, without the need to move the device – bringing a new class of phonon endoscopes at your fingertips.

Beyond clinical health, areas such as precision manufacturing and metrology could use this high resolution tool for surface inspections and material characterization; a complementary or replacement measure for existing scientific instruments. Booming technologies such as 3D bioprinting and tissue engineering could also use the phonon probe as an in-line inspection tool by integrating it directly into the outer diameter of the printing needle.

Next, the team will develop a series of cell and tissue biological imaging applications in collaboration with the Nottingham Digestive Diseases Center and the Institute of Biophysics, Imaging and Optical Science at the University of Nottingham; with the aim of creating a viable clinical tool in the years to come.

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