Prototype probe scans a brain-artery model in 360 degrees

Inside a full-scale human cerebrovascular model, a device no longer than a grain of rice traveled from the femoral artery toward the middle cerebral artery. The prototype, developed by teams at Nanjing University and Nanjing University of Aeronautics and Astronautics, measures 0.55 mm in diameter and 4 mm in length and produced full 360-degree optical scans in testing.

The probe uses optical coherence tomography, or OCT, a light-based technique that creates cross-sectional images of tissue. Its central optical fiber carries near-infrared light to a tiny angled lens. Instead of turning the whole catheter from outside the body, a piezoelectric actuator — a material that shifts slightly under electrical voltage — rotates the lens directly at the tip, sweeping the light around the vessel wall.

That local rotation addresses a problem in smaller, more tortuous brain arteries. Long catheters can twist and rub against the vessel as they move, making an externally rotated probe turn unevenly and distorting the image. The researchers measured about one degree of angular deviation after the catheter passed through their curved vascular model, while the lens reached speeds of up to 58 revolutions per second.

The team produced two- and three-dimensional images of a magnolia leaf’s fine vein network, a vascular stent placed in a middle cerebral artery model and an ex vivo porcine blood vessel. Images of excised human atherosclerotic plaque showed features associated with lipid-rich regions and fibrotic tissue, consistent with conventional histological examination.

And so what, concretely? If the design reaches clinical testing, doctors could gain a closer view of how a stent sits against the wall of a small brain artery and of the plaque surrounding it. That could inform treatment decisions, but the device remains a prototype: the researchers say it needs further development and testing before it can be used in patients.