Aim: Arterial wall elasticity including the circumferential and longitudinal modulus is a measure of sub-clinical cardiovascular disease; the circumferential modulus is increased in acute ischemic stroke (AIS). There are still no reports of non-invasive measurement of longitudinal elastic modulus of arterial wall and its prospect of clinical application. In this study, the longitudinal elastic modulus of the arterial wall was assessed using real-time shear wave elastography in patients with AIS. The technique's feasibility and its related factors were studied initially.
Materials and methods: In this study 179 patients with AIS and 168 age- and sex-matched controls were examined. The pulse wave velocity (PWV) of the bilateral carotid arteries was measured using radio frequency ultrasound technology. The 20 areas of superficial walls of bilateral carotid artery were analyzed by real-time shear wave elastography (SWE), and the average values of longitudinal average elastic modulus (ME-mean), maximum elastic modulus (ME-max), minimum elastic modulus (ME-min), and elastic modulus standard deviation (MESD) were measured.
Results: The PWV, ME-mean, ME-max and ME-sp of the carotid artery in patients with AIS were greater than those in the control group. Age, systolic blood pressure, PWV, and low-density lipoprotein were positively related to ME-mean and ME-max (r=0.221and r=0.248, r=0.174 and r=0.176, r=0.776 and r=0.716, r=0.173 and r=0.200, p<0.05) and were independent risk factors for ME-mean and ME-max ROC curves for detection of ischemic stroke as decided by PWV, ME-mean and ME-max. The area under the curves were 0.55+/-0.03 (p</=0.05), 0.59+/-0.03 (p</=0.05) and 0.60+/-0.03 (p=0.023), respectively. The optimal PWV, MEmean and MEmax cutoff values for the detection of ischemic stroke were 9.66 m/s, 55.4 kPa and 65.4 kPa, with 69%, 73% and 73% sensitivity and 89%, 53% and 51% specificity, respectively.
Conclusions: SWE could measure non-invasively the longitudinal elastic modulus of the arterial wall and evaluate the arterial stiffness. It was equivalent to the PWV which showed circular elastic modulus of arterial wall on evaluating AIS. Age, systolic blood pressure, pulse wave velocity, and low-density lipoprotein were independent risk factors for longitudinal elastic modulus. SWE may be effective in the assessment of arterial stiffness and offer a potential clinical benefit.