Catheter Melds Light and Ultrasound to Detect Plaque

A novel catheter probe combines intravascular ultrasound (IVUS) with fluorescence lifetime imaging (FLIm) in order to help predict heart attacks.

Developed at the University of California Davis (UCD, USA), the 3.7 Fr single rotational intravascular FLIm-IVUS catheter sends short laser pulses into surrounding tissue, which fluoresces in return; different tissues--such as collagen, proteins, and lipids--emit different biochemical fluorescence profiles. At the same time, the IVUS probe in the catheter records structural information on the blood vessel. The combination can provides a comprehensive insight into how atherosclerotic plaque forms, aiding diagnosis and providing a way to measure how plaques shrink in response to therapy.

The researchers successfully demonstrated the ability of the system to acquire robust bi-modal data in coronary arteries in healthy swine via standard percutaneous coronary intervention (PCI) techniques in combination with a Dextran solution bolus flush. They also imaged several representative diseased human samples, showing that different types of lesions in diseased coronary arteries, as identified via histology, are also characterized by specific FLIm biochemical signatures in the first 200 μm of the intima. The study was published on August 21, 2017, in Scientific Reports.

“New imaging techniques for evaluation of plaque pathophysiology are of great interest to both improve the understanding of mechanisms driving plaque formation, as well as support the development of new preventative, pharmaceutical, and interventional therapies,” concluded senior author biomedical engineer Laura Marcu, PhD. “The unique FLIm-IVUS system evaluated here has the potential to provide a comprehensive insight into atherosclerotic lesion formation, diagnostics, and response to therapy.”

IVUS enables identification of plaque burden due to its high penetration depth (up to 10 mm), but lacks the spatial resolution to identify small-scale features such as details of the intima, or the biochemical changes linked with atherosclerotic lesion formation and evolution. FLIm, on the other hand, depends on a wealth of environmental parameters such as pH, ion or oxygen concentration, molecular binding or the proximity of energy acceptors, making it ideal for functional imaging.

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