Microflow3D - Non-invasive Mapping of Coronary Arteries and the Cerebral Vascular Network Using 3D Ultrasound Localization Microscopy in Patients With Atherosclerosis Prior to Carotid Endarterectomy Surgery

Carotid atherosclerosis is associated with a high risk of stroke due to embolization from vulnerable plaques located at the carotid bifurcation. When the degree of stenosis exceeds 60%, carotid endarterectomy is considered to remove the plaque. This is a complex surgical procedure, performed under general anesthesia in most cases, and consists of extracting the plaque. The patient population is typically elderly and particularly fragile, with a significant risk of cerebral infarction during the intervention. To minimize perioperative risks, patients undergo a preoperative evaluation that includes transcranial Doppler ultrasound and coronary angiography. The purpose of transcranial Doppler is to image the circle of Willis and identify patients with an incomplete circle, which would compromise adequate cerebral perfusion during carotid clamping. However, this imaging is challenging because the quality of ultrasound through the skull is often poor, and two-dimensional imaging does not always allow full visualization of the circle of Willis. A high-resolution three-dimensional imaging modality could therefore improve surgical planning. Coronary angiography or CT coronary angiography are performed to image the coronary arteries and identify patients at highest risk of myocardial infarction. A non-ionizing three-dimensional imaging modality with high coronary resolution could also benefit patients by reducing radiation exposure.

Ten years ago, the Physics for Medicine Laboratory developed a novel imaging technique called ultrasound localization microscopy (ULM). This modality combines ultrafast ultrasound imaging (acquiring more than 1000 frames per second) with the injection of microbubbles already used in clinical practice. By individually imaging and localizing these microbubbles, it becomes possible to visualize the vascular networks of the coronary arteries and the brain in animal models with unprecedented resolution and field of view. Recently, the clinical feasibility of ultrasound localization microscopy was demonstrated in two dimensions in the brain of patients with cerebral aneurysms.

Nevertheless, the two-dimensional nature of the imaging represented a limitation. To address this, we developed a new type of wider ultrasound probe capable of imaging large three-dimensional volumes. These probes have already been validated through simulations, phantom studies, and more recently in animal experiments.

In this clinical study, we therefore aim to demonstrate the feasibility of three-dimensional imaging of the microcirculation of the heart and brain in patients during the preoperative evaluation, with the goal of improving surgical planning for carotid endarterectomy.