Miniature optical coherence tomography probe takes pictures inside cerebral arteries

An international team of microtechnologists, medical technologists and neurosurgeons have designed, created and tested a new type of probe that can be used to obtain images from inside the arteries of the brain.

In their paper, published in Science Translational Medicine, the team describes how the probe was designed and built, and how it performed in initial tests.

When patients develop medical problems in the brain, such as blood clots, aneurysms or hardened arteries, the tools available to doctors to diagnose them are limited to imaging technologies that take pictures of the veins and arteries from the outside of the brain. Such images are then used as maps to guide catheter-like devices through veins and arteries to parts of the brain to make repairs.

Intravascular imaging using neuro-optical coherence tomography (nOCT). The nOCT probe is compatible with standard neurovascular microcatheters, integrating with the procedural workflow used in clinical practice. NOCT captures high-resolution three-dimensional optical data, providing volumetric microscopy of tortuous cerebral arteries, surrounding structures and therapeutic devices. Source: Science Translational Medicine (2024). DOI: 10.1126/scitranslmed.adl4497

The problem with this approach is that the images used are not always clear or accurate. They also do not allow the surgeon to see what is happening inside the vein or artery during its repair, which leads to procedures being performed almost blindly.

In this new study, the team created a probe with a camera that is small enough to fit inside a catheter, allowing it to capture near real-time images from inside the veins and arteries of the brain.

The new probe is based on optical coherence tomography, a type of imaging technology used by eye and heart surgeons to treat patients. It generates images by processing the backscatter of near-infrared light. Until now, such devices have been too bulky and rigid for use inside the brain.

To overcome this problem, the research team replaced the components with smaller pieces, such as a fiber optic cable as thin as a human hair. They also used a modified type of glass to make the distal lens, which makes up the head of the probe and allows it to bend.

The resulting probe is mostly hollow and has a worm-like appearance. It also rotates at a speed of 250 times per second, which helps it move easily through the veins and arteries. The camera takes pictures at a frequency proportional to demand. The entire probe fits easily inside the catheter, making it easier to place and move within the arteries and veins of the brain, as well as its removal.

After animal testing, the probe was moved into clinical trials in two locations, one in Canada and the other in Argentina. To date, 32 patients have been treated with the new probe. The team reports that so far the probe has proven to be safe, well tolerated and successful in all cases. They conclude that their new probe is ready for general use.