The Measurement Of Carotid Intimal-Media Thickness Based On Ultrasound Images

Cardiovascular and cerebrovascular diseases (CCVD) are the leading threats to human healthy, early detection of CCVD is crucial to lowering the death rate. The intima-media thickness (IMT) of common carotid artery (CCA) is one of major criteria for early screening and diagnosis of CCVD, and it is widly used in the clinical.Ultrasound imaging is widely used for the intima-media thickness measurement, for it not only contains the information for IMT measurement, but also has many adventages compared with the other image devices, for example, it is noninvasive, economic and safe.So far in clinical, the IMT is usualy measured manually, a trained sonographer manually finds the two interfaces:the lumen-intima (LI) and the media-adventitia (MA) interface, then measure the distance betweent the two interfaces. But the procedure is subjective, time consuming and unreliable.In this thesis we present a semi-automatic method to measure the carotid intima-media thickness based on Ultrasound images. The initial procedure is to select a region of interest (ROI) in the concerned carotid ultrasound image. A modified level set method is employed to segment the IMT by adding local intensity information to the variational Level Set formulation. This mechanism is used twice. In the first step, the boundary between lumen and intima (LI) can be segmented from ultrasonic images by the modified level set method. After we get the LI boundary, we use the similar method to detect the boundary between the media and adventitia (MA). After LI and MA are detected, the IMT can be easily calculated. We compare the result of our method with other methods, and the results show that our method can measure the IMT accurately with less manual inputs and without any pre-processing steps.