A new, noninvasive technique for imaging the carotid artery offers advantages over other imaging methods and could provide an earlier, more accurate assessment of cardiovascular disease risk, according to a study published in the journal Radiology and touted by the Radiological Society of North America.
Ultrasound, CT and MRI are useful for revealing the extent of narrowing in the carotid arteries, but less helpful in determining the makeup of the plaque itself, researchers say. This is a crucial limitation because plaque composition is associated with vulnerability to rupture, setting in motion the chain of events that leads to life-threatening strokes.
“Rapid characterization of tissue function and molecular composition is limited with these modalities, which commonly results in poor diagnostic accuracy and ineffective treatments,” says study senior author Daniel Razansky, PhD, director of the Functional and Molecular Imaging Lab at the University of Zurich and the Swiss Federal Institute of Technology in Zurich.
Razansky and colleagues studied a new technique for carotid artery assessment called volumetric multi-spectral optoacoustic tomography (vMSOT). As with ultrasound, vMSOT is performed with a handheld device that is moved against the neck. However, vMSOT employs the science of spectroscopy to investigate tissue at a molecular scale. This provides information about the artery that is not attainable with other methods. It also can detect lipids, the pigment melanin and other disease-related biomarkers early enough to provide better treatment options.
“Unlike most other clinical imaging modalities mainly looking at late-stage anatomical manifestations of diseases, vMSOT is capable of sensing specific molecules in tissues without administration of contrast agents,” Razansky says. “In the case of carotid artery disease, assessment of the entire bifurcation area in real time and in 3D is only possible with vMSOT.”
The researchers performed vMSOT imaging on 16 healthy participants and compared results with those from conventional ultrasound. The vMSOT approach could noninvasively and instantaneously assess the entire bifurcation area of the carotid artery in three dimensions, thus making it less prone than ultrasound to motion-related, image-blurring artifacts. Researchers says the results point to the tremendous potential of the new approach in the clinic.
“The developed hand-held vMSOT imaging approach holds promise for rapid volumetric assessment of the carotid artery and plaque vulnerability in an entirely noninvasive manner,” Razansky says. “It also has the additional potential for label-free identification and assessment of clinically-relevant biomarkers of carotid artery disease, which helps with early and accurate diagnosis, timely treatment planning and monitoring.”
In the future, vMSOT could be combined with ultrasound for a more comprehensive characterization of the carotid artery. “Given its fast imaging performance, excellent molecular contrast, portability and affordability, I truly believe that vMSOT will soon be routinely used in the clinic,” Razansky says. “One day, it may even become as popular as ultrasound.”
Main image: Images show volumetric multispectral optoacoustic tomographic (MSOT) imaging setup. A, Diagram illustrates handheld noninvasive scanning procedure, where volumetric MSOT probe is scanned on skin surface around carotid artery bifurcation area. B, Three-dimensional view of reconstructed volumetric MSOT image of carotid bifurcation captured at video rate of 10 Hz in a 44-year-old man. CAB = carotid artery bifurcation, CCA = common carotid artery, ECA = external carotid artery, FB = fiber bundle, ICA = internal carotid artery, LB = laser beam, STA = superior thyroid artery, TA = transducer array, TM = transparent membrane, UW = ultrasound waves, WH = water holder.