Each year, thousands of patients undergo brain surgeries for conditions such as aneurysms, brain tumors, or vascular malformations. These procedures often require the temporary closure of brain blood vessels, significantly increasing the risk of stroke. For instance, aneurysm surgeries carry an 8% to 50% risk of stroke, depending on complexity, while brain tumor surgeries have a risk ranging from 12.5% to 44%. Until recently, surgeons had no real-time method to observe changes in cerebral blood flow during such procedures. Effects indicating stroke risk could only be seen afterward, often when it is too late. A new imaging approach now enables real-time monitoring of blood perfusion in brain tissue during surgery, offering the potential to prevent strokes before they occur.

This new technique, developed through a collaboration between UMC Utrecht (Utrecht, Netherlands) and Eindhoven University of Technology (Eindhoven, Netherlandsl), is based on Ultrafast Power Doppler Imaging (UPDI). Researchers adapted the imaging technology to enable the use of high-frequency, ultrafast ultrasound signals from multiple angles to create high-resolution images of cerebral perfusion. The setup was implemented and refined for real-time use in surgical settings. The UPDI method visualizes brain capillaries, quantifies blood volume in the tissue, and continuously shows perfusion dynamics during surgical procedures. It allows surgeons to assess whether brain tissue is adequately perfused when a blood vessel is temporarily closed. The technology is designed to be fast, safe, and easy to integrate into the operating room.

The new technique was piloted on ten patients undergoing brain vessel surgery. During each operation, continuous measurements of blood flow were taken using the UPDI setup. In several cases, the team observed real-time reductions or increases in perfusion, such as immediately after removing a vascular clamp. These subtle yet critical changes, typically only visible later on MRI scans, could now be detected live, according to the study published in Nature Scientific Reports. The approach may also benefit other procedures like kidney transplants, where monitoring organ perfusion is vital. Future research aims to evaluate the technique’s predictive value for stroke and further integrate it into surgical practice to reduce complications and improve patient outcomes.

“Our accurate and high-resolution measurement of blood flow in the brain allows for early detection of reduced perfusion by quantitative analysis of UPDI, such that surgeons can take timely precautions during the operation and prevent severe complications, such as cerebral infarction,” said Massimo Mischi, chair of the Signal Processing Systems Group at Eindhoven University of Technology.

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