Summary of the NSFC/RGC project (Dr. Wei-Ning Lee)
Project Reference: N_HKU713/15
HK Principal Investigator: Dr. Wei-Ning Lee (The University of Hong Kong)
Mainland Principal Investigator: Dr. Jianwen Luo (Tsinghua University)
Cardiovascular diseases (CVDs) remain the primary killer worldwide, responsible for 30% of global deaths. Heart attack and stroke, which dominate the CVDs, are mainly caused by atherosclerosis, a disease that exhibits the formation of plaques in the intima of the artery, leads to wall stiffening and luminal narrowing, and limits the blood supply to tissues. Moreover, abundant research evidence has shown that the rupture of atherosclerotic plaques and thus thrombus formation result in acute blockage of the artery and trigger acute cardiovascular events. The current consensus has suggested the use of functional indices, such as metabolism and microstructural compositions, for the examination of vulnerable plaques, beyond the conventional diagnosis based on morphologic changes. Early detection of vulnerable plaques for subsequent timely intervention will thus greatly reduce mortality rate.
On the other hand, plaques with distinct metabolic conditions and microstructure have demonstrated to exhibit different elasticities. Arterial elasticity (or, stiffness) is therefore a potential functional indicator of atherosclerotic plaque vulnerability, a precursor of vascular disease, and a risk marker of CVDs. Nonetheless, the direct relationship between the mechanical behavior and the pathological state of the arterial wall has not been fully established because of the lack of an imaging framework that gives full access to vascular mechanics and function.
Sonography (i.e., medical ultrasound imaging) remain predominant in clinical practice for the assessment of vascular function because it is free from ionizing radiation, inexpensive, portable, and more compatible with subjects, and in particular, provides superior real-time feedback of morphology, dimensions, and hemodynamics of the artery. At the current stage, functional ultrasound imaging techniques that are capable of quantifying tissue stiffness typically assumes that the arterial wall is homogeneous and isotropic. However, the known complex microstructure of the artery suggests the structural, and thus mechanical, anisotropy of the arterial wall. The imperative assessment of anisotropic mechanical properties in radial, longitudinal and circumferential axes of the artery will allow a better understanding of disease progression and shed light on the structure-function relationship of the artery.
Collaborating with a team led by Dr. Jianwen Luo at Tsinghua University, we are developing a comprehensive vascular ultrasound imaging framework that incorporates our in-house ultrasound elasticity imaging techniques. This project particularly centers on the common carotid artery because its superficial locality facilitates higher ultrasound image quality and noninvasive image acquisitions. The ultimate goal of this framework is to quantify and map both kinematic and mechanical properties of the artery in both normal and atherosclerotic conditions in full aspects, from computational modeling to in vitro phantom experiments and a clinical study for 1) a better understanding of vascular mechanics, 2) risk assessment of atherosclerotic plaques, and 3) personalized computational modeling of the artery.