California researchers combine imaging techs to better detect high-risk atherosclerosis

IVUS-OCT catheter (top), OCT image (left) and IVUS image--Courtesy of National Institute of Biomedical Imaging and Bioengineering

Several tests exist to detect atherosclerosis, the plaque buildup in arteries that can lead to heart attack and stroke, but each has its limitations. NIH-supported labs at UC Irvine and the University of Southern California have combined two types of imaging to create a promising new method to identify atherosclerotic plaques.

They combined intravascular ultrasound (IVUS) and optical coherence tomography (OCT) to provide unprecedented depth and detail in screening for a difficult-to-visualize type of plaque, the NIH said in a statement. Thin-cap fibroatheroma (TCFA) are susceptible to rupture due to a large necrotic core and thinner fibrous caps surrounding the core. The rupture of plaque lining an artery is the leading cause of deaths from heart disease. The combination method marries IVUS' ability to see deep into the plaque with OCT's ability to capture the fibrous caps in fine detail.

The labs tested the IVUS-OCT system in healthy rabbits and rabbits that had atherosclerosis, as well as in human tissue from cadavers. After imaging, they sliced and stained the human tissue to confirm the location of TCFA plaques, the NIH said. Two doctors independently evaluated IVUS, OCT and IVUS-OCT images. They were unable to identify TCFA plaques when using IVUS or OCT alone, but succeeded when using the combination method. The findings were published in Scientific Reports.

Differing imaging speeds previously prevented the technologies from being used in tandem. Using new technology, including a customized catheter and improved ultrasound inducer, the team settled on a compromise between optimal imaging speeds, resulting in a system that can visualize 7 centimeters of artery in four seconds. The system's potential applications beyond identifying TCFA include detecting other structures and lesions, including calcification, said Kirk Shung, a professor of biomedical engineering at USC and one of the authors, in the statement.

"This work has overcome many of the challenges of doing IVUS and OCT simultaneously," said Zhongping Chen, a UC Irvine professor of biomedical engineering and senior author, in the statement. Previous attempts to combine them have involved sacrificing image quality, prolonging procedure time, or using two catheters and increasing prices.

"When you use a single catheter, you don't have to worry about matching two images, which enables physicians to look at co-registered ultrasound and OCT images simultaneously in real time. It will make identifying plaques easier and more precise, allowing for better treatment decisions," Chen said. OCT Medical Imaging, cofounded by Chen, has licensed the technology. It recently received a Small Business Innovation Research grant from the National Heart, Lung and Blood Institute to accelerate the technology into clinical applications.

- here's the statement