As plaque accumulates on the inside of arteries, it can cause the arteries to thicken and harden. When that plaque ruptures, it can ultimately block blood flow and lead to a heart attack, stroke or other problem throughout the body.

The condition, known as atherosclerosis, is a major form of cardiovascular disease, which over the past century has become the leading cause of death worldwide. Currently, no imaging tools are available to consistently and accurately diagnose plaque at risk of rupturing in living patients.

A new imaging system known as intravascular photoacoustic (IVPA) imaging that produces 3D images of the insides of arteries has the potential to help doctors diagnose plaques on the brink of rupturing. Previously, scientists have struggled to develop imaging instruments that meet clinical requirements while illuminating arteries to a useful depth and at quick enough speeds.

Now, a team of researchers from Purdue University, Indiana University School of Medicine, Indiana, U.S. and the Shanghai Institute of Optics and Fine Mechanics, Shanghai, China, have improved upon previous instruments, developing a new IVPA catheter design with collinear overlap between optical and acoustic waves with a tiny probe. The design can greatly improve the sensitivity and imaging depth of IVPA imaging, revealing fatty arteries in all of their unctuous detail.

IVPA imaging works by measuring ultrasound signals from molecules exposed to a light beam from a fast-pulsing laser. The new probe allows the optical beam and sound wave to share the same path all the way during imaging that’s the “collinear” overlap part rather than cross overlap as in previous designs.

This increases the sensitivity and the imaging depth of the instrument, allowing for high-quality IVPA imaging of a human coronary artery over 6 mm in depth from the lumen, the normally open channel within arteries, to perivascular fat, which surrounds the outside of most arteries and veins.

The Cheng laboratory had previously tried a design based on a ring-shaped transducer to accomplish the same collinear overlap idea. However, the size of the transducer prevented its further application in clinic. The team came up with the current design by transmitting the optical wave while reflecting the sound wave on an angled surface.

The presentation, “Highly Sensitive Intravascular Photoacoustic Imaging with a Collinear Catheter Probe,” by Y. Cao, A. Kole, P. Wang, M. Sturek and J. Cheng will take place on Thursday, 9 June 2016 in the Salon I and II of Marriott San Jose, San Jose, California, USA.

Purdue University
www.purdue.edu

Shanghai Institute of Optics and Fine Mechanics
www.english.siom.cas.cn