While ultrasound is one of the most common medical imaging tools, conventional electronic ultrasound devices tend to be bulky and cannot be used at the same time as some other imaging technologies. A new ultrasound system that uses optical, instead of electronic components, could improve performance while giving doctors significantly more flexibility in how they use ultrasound to diagnose and treat medical problems.
In The Optical Society (OSA) journal Biomedical Optics Express, researchers demonstrate for the first time the use of an all-optical ultrasound imager for video-rate, real-time 2D imaging of biological tissue. The achievement is an important step toward making all-optical ultrasound practical for routine clinical use.
Because they require no electronic components in the imaging probe, all-optical ultrasound systems could be safely used at the same time as magnetic resonance imaging (MRI) scanners. This would give doctors a more comprehensive picture of the tissues around an area of interest, such as a tumor or blood vessel.
Lightbeam scanning mirrors built into the device increase image quality and make it possible to acquire images in different modes. In a clinical setting, this would allow doctors to rapidly toggle between modes on a single instrument to suit the task at hand. Acquiring different types of images using conventional ultrasound systems typically requires separate specialized probes.
Conventional ultrasound imagers use arrays of electronic transducers to transmit high-frequency sound waves into tissue and receive the reflections. A computer then constructs images of the tissue.
By contrast, all-optical ultrasound imagers use light to both transmit and receive ultrasound waves. Pulsed laser light is used to generate ultrasound waves, and scanning mirrors control where the waves are transmitted into the tissue. A fiber optic sensor receives the reflected waves.
The electronic components of conventional ultrasound devices make them difficult to miniaturize for internal use, so most existing ultrasound devices are large, handheld probes that are placed against the skin. While some high-resolution minimally invasive ultrasound probes have been developed, they are too expensive for routine clinical use. Optical components are easily miniaturized and tiny all-optical ultrasound probes would likely be significantly less expensive to manufacture than compact electronic ultrasound systems, researchers say.
To generate images, an all-optical ultrasound system must acquire data from multiple optical source locations, combine them together and then create a visualization that reconstructs the area being imaged.
Researchers have previously demonstrated using all-optical ultrasound to generate high-quality 2D and 3D images, but acquiring the images took hours, making these devices too slow to be used in a clinical setting. The new demonstration is the first to acquire and display images with all-optical ultrasound at video rates.
