New Imaging Technique Can Take 3-D Pictures of Arterial Plaque

Researchers at Purdue University (West Lafayette, IN) have developed a new type of imaging technology to diagnose cardiovascular disease and other disorders by measuring ultrasound signals from molecules exposed to a fast-pulsing laser. The new method could be used to take precise 3-D images of plaques lining arteries, remarks Ji-Xin Cheng, an associate professor of biomedical engineering and chemistry.

The new technique uses nanosecond laser pulses in the near-infrared range. The laser generates molecular 'overtone' vibrations, or wavelengths that are not absorbed by the blood. The pulsed laser causes tissue to heat and expand locally, generating pressure waves at the ultrasound frequency that can be picked up with a transducer. In contrast, other imaging methods that provide molecular information are unable to penetrate tissue deep enough to reveal the 3-D structure of the plaques.

This method reveals the presence of carbon-hydrogen bonds in the lipid molecules found in arterial plaques that cause heart disease. It might also be used to detect fat molecules in muscles to diagnose diabetes and other lipid-related disorders, including neurological conditions and brain trauma. Because the technique reveals the nitrogen-hydrogen bonds that make up proteins, it might also be useful for diagnosing other diseases and studying collagen's role in scar formation.

"We are working to miniaturize the system so that we can build an endoscope to put into blood vessels using a catheter," Cheng says. "This would enable us to see the exact nature of plaque formation in the walls of arteries to better quantify and diagnose cardiovascular disease."