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Researchers have created a 3D imaging system to analyse blood flow in limbs, which could be used to asses risk of diseases, such as cancer and arteriosclerosis (the clogging of the arteries).

In their research article published on F1000Research, the team of researchers from Canon, Kyoto University, Japan Science and Technology Agency, Japan Probe and Hitachi, discuss how the photoacoustic device they developed can scan blood vessels in human limbs to produce high resolution 3D images in real time. In this blog, we showcase the images that are produced from the scans and tell you more about the clinical applications.

Vascular trees – our life support

Blood vessels are essential to sustaining human life, carrying oxygen and nutrients to tissues in the entire body. Abnormalities and physiological changes to our arteries and veins can have severe health consequences.

Clinicians can assess cardiovascular health by visualising the blood flow in arteries, as well as view abnormalities which could indicate cancer or inflammation. So, researchers are developing techniques to improve the quality of imaging these blood vessels to help clinicians assess these structures to diagnose disease.

Real time imaging

Current clinical practices for imaging blood vessels may either expose patients to x-ray radiation or patients undergo a magnetic resonance imaging scan, which relies on expensive equipment. A team of researchers from Japan working at Canon, Kyoto University, Japan Science and Technology Agency, Japan Probe and Hitachi, have designed a photoacoustic imaging system to produce high quality still shots and motion images.

This imaging prototype, named PAI-05, is a non-invasive system providing high resolution 3D images of blood vessels in real time. Clinicians can study the scans to assess abnormalities, angiogenesis (formation of new blood vessels) and tortuosity.

3D reconstruction

PAI-05 is a photoacoustic imaging system that produces images using light energy that is absorbed by tissues and converted into heat. The temperature rise causes thermal expansion, which emits ultrasound waves that are detected by light absorption detectors. These are then processed, thereby producing a 3d reconstruction of our blood vessels.

The scanning system overcomes the spatial limitations of current blood flow imaging, providing a wider angle and field of view than that of current linear models, which gives a more complete image of the vasculature system. This could make it easier for clinicians to diagnose conditions, as well as being able to scan limbs from multiple angles and over larger areas.

Corresponding authors Yasufumi Asao from Japan Science and Technology Agency, and Kenichi Nagae, from Canon, say: “It is a promising prototype that provides high morphological reproductions of our own vascular structures in our bodies. We based our design on a photoacoustic imaging system that was previously used to specifically scan breasts. This system relies on a hemispherical detector array which reconstructs blood vessels of living tissue in 3D. We updated this with a higher density sensor so that even small vessels are visualised with good resolution and contrast.”

The new imaging table has a flat rectangular tray to improve the patient’s comfort during the scanning process. The prototype has only been tested with one human subject where scans were taken of their hands, feet, legs and arms. Clinical research in patients will be carried out in future.