Scientists have developed a compact Raman imaging system that can reliably tell cancerous tissue apart from normal tissue. The approach could support earlier cancer detection and help move advanced molecular imaging tools beyond research laboratories and into more practical clinical settings.

The imaging system is designed to detect extremely weak signals from surface-enhanced Raman scattering (SERS) nanoparticles that are engineered to attach to tumor markers. Once these nanoparticles are applied to a sample or to the area being examined, the system reads their Raman signal and automatically highlights regions that are more likely to contain tumor tissue.

"Traditional methods for cancer-related diagnosis are time-consuming and labor-intensive because they require staining tissue samples and having a pathologist look for any abnormalities," said research team leader Zhen Qiu from the Institute for Quantitative Health Science and Engineering (IQ), Michigan State University. "While our system would not immediately replace pathology, it could serve as a rapid screening tool to accelerate diagnosis."

Published results show major gains in sensitivity

In Optica, Optica Publishing Group's journal for high-impact research, Qiu and colleagues report that their system can distinguish cancerous cells from healthy ones while detecting Raman signals that are about four times weaker than those measured by a comparable commercial system. This improved sensitivity comes from combining a swept-source laser -- which changes wavelength during analysis -- with an ultra-sensitive detector called a superconducting nanowire single-photon detector (SNSPD).

"This technology could eventually enable portable or intraoperative devices that enable clinicians to detect cancers at earlier stages, improve the accuracy of biopsy sampling and monitor disease progression through less invasive testing," said Qiu. "Ultimately, such advances could enhance patient outcomes and reduce diagnostic delays, accelerating the path from detection to treatment."

Pushing detection limits with superconducting detectors

Qiu's lab studies how SNSPDs can be used to enhance a range of imaging technologies. SNSPDs rely on a superconducting wire that can detect individual particles of light, allowing the system to capture extremely weak optical signals at high speed while keeping background noise very low.

For this project, the researchers aimed to build a platform that could measure Raman signals far fainter than those detected by existing Raman systems. Raman imaging works by mapping a sample's chemical composition through the unique light-scattering fingerprints of its molecules. These signals can be strengthened by using SERS nanoparticles.

"Combining this advanced detector with a swept-source Raman architecture that replaces a bulky camera and collects light more efficiently resulted in a system with a detection limit well beyond that of comparable commercial systems," said Qiu. "Also, the fiber coupling configuration and compact design facilitate system miniaturization and future clinical translation."