Carotid Plaque Characterization Using Innovative Ultrasound Techniques

Condition(s) studied

Investigational drug(s) / intervention(s)

blood sampling: This procedure will take place once during the patient's CARPUS first visit (Croix Rousse hospital (Hospice civils de Lyon). A peripheral venous line of the cathlon 24 G type with tap without tubing will be inserted by a nurse. A blood sample will be taken at the same time to check creatinine levels before the MRI scan and to record the patient's cholesterol levels for the eCRF.

ultrasound imaging exam: This procedure takes place once immediately after the intervention 1. The patient will first have an ultrasound acquisition with the clinical ultrasound scanner (\~5 minutes) in order to locate the plaque. An acquisition with the research ultrasound scanner and matrix probe will then be performed for measurement for ultrasound spectroscopy (\~5 minutes). An injection of 2.4 ml Sonovue followed by 10 ml saline will be performed during acquisition with the research ultrasound scanner for ultrasound localization imaging measurement (\~10 minutes). The patient must remain under observation (in the waiting room) for 30 minutes after the examination.

High resolution MRI plaque exam: This procedure will take place once during the patient's CARPUS second visit (Pierre Wertheimer hospital (Hospice civils de Lyon)). The patient is greeted in radiology, and his/her identity and absence of contraindications are verified. A peripheral venous line of the cathlon 24 G type with tap without tubing will be inserted by a nurse. Injection of gadolinium and MRI examination of the plaque used in clinical routine.

Study summary

Strokes are the second leading cause of disability and death worldwide (according to World Health Organization in 2019). They are ischemic in origin in 80% of cases. Atheromatous disease, and more specifically carotid stenosis, is responsible for 20% of these ischemic strokes. Current recommendations, based on high levels of evidence, consider only the degree of carotid artery stenosis to define the threshold for surgical treatment. However, it is now accepted that the composition and rate of progression of atherosclerotic plaque are also criteria to be considered when selecting patients at high risk of stroke. The presence of hemorrhage and a lipid core in the atheromatous plaque, both factors of instability, is associated with a greater risk of ipsilateral ischemic events. The presence of intraplaque hemorrhage is therefore a marker of plaque instability. In this context, techniques for in vivo analysis of atherosclerotic plaque composition need to be developed to better target patients for surgery.

Ultrafast ultrasound enables imaging rates of several thousand images per second. Ultrasound Localization Microscopy (ULM) gives access to the vascular microstructure of tissues: the localization of injected microbubbles, which enhance the ultrasound signal in vessels, and the tracking of these microbubbles enable the vascularization of the tissue in question to be mapped. Ultrasound spectroscopy qualifies tissue microstructure: this operator- and system-independent technique is based on frequency analysis of ultrasound signals backscattered by tissue, and more specifically on analysis of the backscatter coefficient (BSC). Measuring the BSC is intrinsic to the tissue, and provides quantitative parameters on the scatterers to qualify the tissue.

The study hypothesis is that these two ultrasound techniques will provide information on the characteristics of the atherosclerotic plaque: the presence of neovessels and biomarkers linked to its composition, including intraplaque hemorrhage.

Eligibility

Primary outcome measure(s)

• Volume of neovessels in carotid atherosclerotic plaques by ULM — between 6 and 59 days after inclusion
  From the vascularization cartography obtained by ULM, the volume of vascularization of the plaque will be estimated (number of pixels with vascularization compared with the number of pixels in the plaque x100). Plaques can then be described by neovessel volume distribution.
• Mean velocity in neovessels in carotid atherosclerotic plaques by ULM — between 6 and 59 days after inclusion
  From the vascularization cartography obtained by ULM, the mean velocity (mm/s) in all the neovessels will be estimated.
• Location of neovessels in carotid atherosclerotic plaques by ULM — between 6 and 59 days after inclusion
  The main location of vessels will also be described according to their topography in the plaque (e.g. central, peripheral, both).

Trial sites (1)

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