The Interference Suppression In The Estimation Of The Carotid Artery Pulsation Based On The Main Feature Rigid-registration Of Ultrasound B-mode Images

Cardiovascular disease, a common disease threatening human health, presents high rate of incidence, morbidity, mortality and recurrence, as well as more complications. Even if the application is the most advanced with perfect treatment at present, there are still more than half of the survivors can not take care of themselves. Therefore, the early diagnosis and prevention are particularly important. The clinical and experimental studies show that the blood vessel wall could be thickened, and the elasticity and pulsation displacement decreased obviously in the early stage of the cerebrovascular diseases. The pulsation displacement of the vessel wall is an important indicator for the diagnosis of vascular diseases. Therefore, it is very important for the cerebrovascular diseases prediction and diagnosis by extracting the true pulsation displacement of the pipe wall.B-mode ultrasonic can image quickly and coherent. The real-time imaging speed can reach 20 to 100 per second. It is widely used in cardiovascular, digestive and other viscera disease diagnosis. It is also used in detection of carotid artery in clinical commonly. However, In the process of ultrasonic Detecting, due to the influence of casual movements of transducer holding by the operator and breathe of the subjects and so on, the collected ultrasound images contains much interference which can be affect the analysis of ultrasound images, and then influence the accurate diagnosis of the disease. The interference can be eliminated and obtain the more accurate pulsation displacement of the pipe wall by selecting the gray information of whole image as the feature in continuous scanning of carotid artery B-mode ultrasound image, and using the method of rigid registration. But some features which have nothing to do with the interference can affect the registration result, and then affect the interference removal. Therefore,In order to get the accurate pulsation displacement of the pipe wall, an algorithm based on the main feature rigid-registration of ultrasound B-mode images is proposed in this thesis to remove the interference.We need to select and design the feature space, the search space, the search strategy and the similarity measure before image registration, among them the selection and design of the feature space determines the speed and the robustness of registration algorithm. Through the analysis of carotid artery ultrasound image found that the movement of the tissue, which is far from the blood vessel, is mainly caused by the interference that can be considered the main feature reflecting the interference motion, however the movement of blood vessel is unrelated to the interference and has little worthy for interference removal. Therefore, in order to improve the accuracy of registration and reduce the data processing time, we put forward to remove the blood vessels and surrounding tissues, then compress and stitch it as the main feature of the image to registration In the aspect of similarity measure, the Normalized mutual information with overlapping invariance and the Enhanced mutual information using spatial information between pixels are presented to make the registration result more accurate.In this paper, simulation and clinical experiments are carried out, and the results demonstrate that compared with the registration method with full ultrasound B-mode images, the normalized mean square error of the proposed registration approach based on main feature in images was reduced by 22%, the time per image registration required is reduced by 26%. The conclusion is drawn that the method proposed in this paper not only remove the interference effectively but also reduced calculation complex and processing time.