Evaluation Of The Bi-dimensional Motion Of The Carotid Artery Wall In Ultrasound

The World Health Statistics report shows that cardiovascular disease has surpassed cancer as the greatest threat to the health of people all around the world since 2008,the incidence and mortality of the disease ranked first in the world.Cardiovascular disease involves abnormality of the whole blood circulation system,and can not be completely cured even with the most advanced and comprehensive treatment.The main cause of cardiovascular disease is atherosclerosis whose early symptom shows that the vascular wall is getting thicker and harder,thereby reducing the vascular elasticity.The detection of two-dimensional motion of blood vessel wall is the basis of vascular elasticity,so the two-dimensional motion of the vascular wall is considered as an important marker of cardiovascular events in recent years.In this paper,we proposed a method to estimate the motion of the carotid artery,which could provide useful information for the health of the vessels and help us to effectively treat patients with subclinical high-risk early.The method assesses the longitudinal and radial motion from clinical in vivo B-mode ultrasound sequences.To estimate the trajectory of a selected point during the cardiac cycle,we introduce a block matching method that involves a temporal update of the reference block using a pixel-wise non-linear Unscented Kalman filter.The filter uses the initial gray-level of the pixel as control signal to avoid divergence due to cumulating errors.In the paper,we not only compared the results with previous research methods,but also contrasted different matching criteria in the block matching method and the different sigma strategies in the unscented transformation,and compared the initial values with the experimental results at the same time.In the comparison of the results,we also compared the difference in the physical status,gender and age subjects of the subjects’ situation to analyze the small difference among them.The motion tracking results were then analyzed with the following aspects: correlation,agreement as well as the error,comparing to the manual tracing results.The correlation was investigated by the linear regression.This analysis approach can measure the statistical relationships between the motion trajectories of the common carotid artery(CCA)wall performed by our approach and the manual tracing method,according to three indices: the Pearsons correlation coefficient,the measurement error and the systematic error.We have tested our approach on a set of 103 subjects,and compared the motion tracking results with traditional methods and the manual tracing method performed by two ultrasound physicians.The experimental results show that our approach is highly correlated(correlation coefficient equals 0.9957 for the longitudinal motion and 0.9959 for the radial motion)and well agreed(the 95% confidence interval width is 0.8871 mm for the longitudinal motion and 0.4159 mm for the radial motion)with the manual tracing method,and perform better than the other methods.These results can demonstrate the effectiveness of our approach in the motion tracking of the common carotid artery wall.