Improved Arterial Inner Wall Detection Using Generalized Median Computation Da-Chuan Cheng *1 , Arno Schmidt-Trucks¨ ass 2 , Shing-Hong Liu 3 , and Xiaoyi Jiang 4 1 Department of Radiological Technology, China Medical University, Taiwan 2 Department of Prevention, Rehabilitation and Sports Medicine, TU M¨ unchen, University Hospital, Germany 3 Department and Graduate Institute of Computer Science and Information Engineering, Chaoyang University of Technology, Taiwan 4 Department of Mathematics and Computer Science, University of M¨ unster, Germany Abstract. In this paper, we propose a novel method for automatic detection of the lumen diameter and intima-media thickness from dynamic B-mode sono- graphic image sequences with and without plaques. There are two phases in this algorithm. In the first phase a dual dynamic programming (DDP) is applied to detect the far wall IMT and near wall IMT. The general median curves are then calculated. In the second phase, the DDP is applied again using the median curves as the knowledge to obtain a more informed search and to potentially correct er- rors from the first phase. All results are visually controlled by professional physi- cians. Based on our experiments, this system can replace the experts’ manual work, which is time-consuming and not repeatable. 1 Introduction Arterial IMT analysis Common carotid artery intima-media thickness (CCA-IMT) measurements have been confirmed to be an early marker of atherosclerosis [1] and have been associated with a higher risk of stroke [2] and myocardial infarction [3]. The non-invasive sonographic examination has demonstrated its potential in early predicting cardiovascular diseases. The IMT is an important index in modern medicine and can be measured either manually [4] or automatically [5–11]. Arterial elasticity analysis Moreover, the carotid artery stiffness (CS) (or elasticity) is one of the important factors for predicting cardio-vascular (CV) events [12]. The factor CS can be measured via measuring the systolic and diastolic carotid diameter on the distal wall of the CCA, 1 to 2 cm beneath the bifurcation with high-precision sonographic modality. Firstly, carotid distensibility (CDist) is estimated through the variations in arterial cross-sectional area and blood pressure (BP) during systole based on the assumption of a circular lumen. CDist is calculated as CDist=∆A/A · ∆P , where A is diastolic lumen area and ∆A is the maximum area change during a systolic- diastolic cycle, and ∆P is the local blood pressure change measured by an applanation tonometer. This pressure change can be approximated by the pressure change measured on the arm in case that the applanation tonometer is deficient. This can be easily done in the routine examination. The CDist can be converted to CS by giving CS=(CDist) -1/2 [12].