New laser-based technology to diagnose heart disease

A new laser-based technology that takes precise 3D images of dangerous plaques lining arteries and identifies deposits that are likely to rupture and cause heart attacks has been developed.

The imaging shows the presence of carbon-hydrogen bonds making up lipid molecules in arterial plaques that cause heart disease, said Ji-Xin Cheng, a professor in Purdue University's Weldon School of Biomedical Engineering and Department of Chemistry.

Researchers are close to commercialising the medical imaging technology that could diagnose cardiovascular disease by measuring ultrasound signals from molecules exposed to a fast-pulsing laser.

"This allows us to see the exact nature of plaque formation in the walls of arteries so we can define whether plaque is going to rupture," said Michael Sturek, co-author of the paper and a professor and chair of the Department of Cellular and Integrative Physiology at Indiana University School of Medicine.

"Some plaques are more dangerous than others, but one needs to know the chemical makeup of the blood vessel wall to determine which ones are at risk of rupturing," said Sturek.

Research in the area has been hindered by the inability to perform high-speed imaging in tissue.

The researchers solved the problem by developing a Raman laser using a laser that produces 2,000 pulses per second, each pulse capable of generating an image, representing a 100-fold increase in the imaging speed of the new technology, called intravascular photoacoustic imaging.

"This innovation represents a big step towards advancing this technology to the clinical setting," Cheng said.

The imaging technique is "label free," meaning it does not require samples to be marked with dyes, making it appealing for diagnostic applications.

The technology is being commercialised by the company Vibronix Inc, co-founded by Cheng and Purdue postdoctoral research associate Pu Wang.

The laser, which pulses in the near-infrared range of the spectrum, causes tissue to heat and expand locally, generating pressure waves at the ultrasound frequency that can be picked up with a device called a transducer.

The system is small enough to be incorporated into an endoscope to put into blood vessels using a catheter, said Cheng.

The near-infrared laser causes enough heating to generate ultrasound but not enough to damage the tissues.

The research was conducted with intact pig tissue and will expand to research with live animals and then clinical studies with humans, researchers said. The finding was published in the Nature journal Scientific Reports.