In 2021, Luxonus, a Japanese startup, created an extraordinary picture of the medial side of a lower leg. In vivid, colourized 3D, the image showed the complex fretwork of small and large vessels inside the leg and the flow of blood through it. Compared to any other type of medical imaging, the detail is unprecedented. Luxonus used its new device, a game-changing photoacoustic 3D scanner that deploys the relatively new science of photoacoustic imaging.
“Our technology is based on the results of a five-year research project, conducted by ImPACT, on 3D imaging of blood vessels,” says Takayuki Yagi, the chief technology officer at Luxonus, and one of the programme managers of ImPACT — a large national project, run by Japan’s Cabinet Office, to promote high-risk, high-impact research and development.
The Luxonus photoacoustic imaging device is a next-generation medical imaging technology that generates much more data, in far greater detail, with less risk and less burden for patients and operators, and at a significantly lower cost than ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI).
Luxonus’ scanner works by directing a pulsed laser beam at the area to be imaged. In the case of the blood circulatory system, the haemoglobin in blood generates ultrasonic waves in response to the laser. “Then, by scanning with our unique hemispherical detector array, we can create 3D images of a wide range of blood vessel structures running in various directions,” says Yagi. The resulting image maps the architecture of the vascular network with unprecedented clarity, up to a 0.1 millimetre resolution.
3D images of the blood vessels inside a hand, leg, and foot.Credit: Luxonus
Cutting-edge technology at your fingertips
Photoacoustic imaging has been around for about 20 years, but Luxonus is one of the few companies to have built a photoacoustic imaging device that produces 3D images. Of the few devices that can produce 3D images, only the Luxonus version can produce an image as large as 18 x 29 centimetres and up to a depth of 3 centimetres.
“We have also developed real-time image reconstruction using a high-power, two-wavelength pulsed laser,” adds Yagi. The wavelengths offered are 797 and 835 nanometres or 756 and 797 nanometres. Unlike MRI and CT, the photoacoustic 3D scanner is able to detect the oxygen saturation of the blood and to distinguish between blood vessels and indocyanine green — a popular medical diagnostic dye. Furthermore, by holding the array at the same position, detailed 4D visualization, such as real-time movement and pulsation of arteries in a fingertip is possible.
The advantages of the photoacoustic 3D scanner over MRI and CT are many. Unlike MRI and CT, the photoacoustic 3D scanner is able to allow for colour differentiation of veins and arteries to detect the oxygen saturation of the blood. Unlike CT scans, no contrast agent is required for vascular imaging, and radiation, such as X-rays or the powerful magnetic fields used in MRI, poses no risk to either patient or machine operator. Perhaps the most promising advantage is that Luxonus imaging may be carried out in an office. A scan can be as simple as laying a hand on a detection pad and holding it still.
Not just for diagnosis
There is also great potential for use in vivo animal research. Tumours implanted into mice and imaged with a photoacoustic 3D scanner for animals (under ethical review and approval by the animal experiment committee) revealed the delicate growth of blood vessels in the tumours. The ongoing vascularization of a tumour, as well as the impact of chemotherapy, can be checked daily. Likewise, the spread of an injected drug could be monitored in real time.
Blood vessels in a mouse's tumour can be imaged using Luxonus' photoacoustic 3D scanner for animals. Credit: Luxonus
The applications of Luxonus’s photoacoustic imaging are extensive. The Luxonus device offers particular benefits in the detection and progression of diseases, such as diabetes, cancer, vasculitis, arteriosclerosis, arthropathy and lymphedema. It can also visualize structures of skin, moles, and hair without a biopsy, opening the door for use in dermatology. In sports and health sciences, the impact of exercise on the vascular network, which is normally measured by blood tests, can be easily quantified.
The Luxonus device offers an unprecedented capacity to observe the structure and function of the microvascular network. “We expect that it will open the door to a new health science to study vascular and lymphatic vessels in a safe and simple manner,” says Sadakazu Aiso, Luxonus’s chief executive officer. In this new, unified vascular science, many opportunities for non-invasive, low-cost early detection of disease processes may be brought together for the benefit of patients and society as a whole.
For more details about Luxonus, please visit their LinkedIn page.
For more information on Luxonus' animal imaging, please see this video: