When patients arrive at emergency rooms with stroke symptoms, rapid diagnosis is crucial. Currently, determining whether a stroke is caused by a clot or a bleed often depends on large CT scanners that are not always available in ambulances or rural clinics. This limitation can delay critical treatment.
Researchers have long considered the possibility of using portable microwave imaging devices to address this gap. These devices could detect changes in brain tissue without radiation and outside shielded rooms. However, the challenge has been the speed required to process the raw data into usable images.
"The hardware can be portable," said Stephen Kim, Research Professor in the Department of Biomedical Engineering at NYU Tandon. "But the computations needed to turn the raw microwave data into an actual image have been far too slow. You can't wait up to an hour to know if someone is having a hemorrhagic stroke."
Kim, together with Ph.D. student Lara Pinar and Department Chair Andreas Hielscher, recently published research in IEEE Transactions on Computational Imaging that addresses this issue. Their new algorithm reconstructs microwave images 10 to 30 times faster than previous methods.
The breakthrough came from changing how the mathematical problem was approached rather than building new hardware. Traditional algorithms require repeated accurate calculations at every step, which slows down processing time significantly. The team's method allows for quicker initial approximations and increases accuracy only when necessary.
"You could almost hear the computer groan," Kim recalled about earlier reconstruction attempts. "It was like trying to push a boulder uphill. We knew there had to be a better way."
Additional improvements included compact mathematical representations and more stable modeling for complex head shapes, further reducing computation times.
With these advancements, image reconstructions that previously took nearly an hour now appear in under 40 seconds during tests with experimental data from devices such as those developed at the University of Manitoba.
"We always knew microwave imaging had the potential to be portable and affordable. But without rapid reconstruction, the technology couldn't make the leap into real clinical settings," Hielscher said. "Now we're finally closing that gap."
Potential applications go beyond stroke diagnosis; portable microwave imaging could serve as an alternative for mammography in resource-limited areas or monitor brain swelling without repeated CT scans.
The team’s next goal is adapting their algorithm for full 3D imaging, moving closer toward practical use in healthcare settings.
"We're taking a technology that has been stuck in the lab for years and giving it the speed it needs to matter clinically," Kim said. "That's the part that excites us: imagining how many patients someday might benefit from this."
