Research Article Automatic Characterization of the Physiological Condition of the Carotid Artery in 2D Ultrasound Image Sequences Using Spatiotemporal and Spatiospectral 2D Maps Hamed Hamid Muhammed 1 and Jimmy C. Azar 2 1 School of Technology and Health (STH), Royal Institute of Technology (KTH), Alfred Nobels Alle 10, SE-141 52 Huddinge, Sweden 2 Centre for Image Analysis, Uppsala University, P.O. Box 337, 751 05 Uppsala, Sweden Correspondence should be addressed to Hamed Hamid Muhammed; hamed.muhammed@sth.kth.se Received 4 December 2013; Revised 2 March 2014; Accepted 19 April 2014; Published 28 May 2014 Academic Editor: Kenji Suzuki Copyright © 2014 H. Hamid Muhammed and J. C. Azar. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A novel method for characterizing and visualizing the progression of waves along the walls of the carotid artery is presented. he new approach is noninvasive and able to simultaneously capture the spatial and the temporal propagation of wavy patterns along the walls of the carotid artery in a completely automated manner. Spatiotemporal and spatiospectral 2D maps describing these patterns (in both the spatial and the frequency domains, resp.) were generated and analyzed by visual inspection as well as automatic feature extraction and classiication. hree categories of cases were considered: pathological elderly, healthy elderly, and healthy young cases. Automatic diferentiation, between cases of these three categories, was achieved with a sensitivity of 97.1% and a speciicity of 74.5%. Two features were proposed and computed to measure the homogeneity of the spatiospectral 2D map which presents the spectral characteristics of the carotid artery wall’s wavy motion pattern which are related to the physical, mechanical (e.g., elasticity), and physiological properties and conditions along the artery. hese results are promising and conirm the potential of the proposed method in providing useful information which can help in revealing the physiological condition of the cardiovascular system. 1. Introduction Despite the promising fact that the consequences of cardio- vascular diseases (CVD) have decreased considerably during the past two decades due to considering healthier lifestyles and using more eicient treatment regimens, these diseases are still accounting for at least 30% of global deaths, as can be, for example, found in Gebel [1]. In addition, these diseases are still the major cause of deaths in developed countries, as reported by Lloyd-Jones et al. [2] and Roger et al. [3]. Consequently, the costs associated with the diagnosis and treatment of CVD are already heavy and are still increasing every day. herefore, the CVD risk stratiication algorithms have recently gained increasing attention [4, 5]. In addition, it can be noticed that the majority of serious cardiovascular events occur in subjects or cases at low or intermediate risk [6, 7]. However, the population-based risk algorithms sufer from poor individual predictive ability. herefore, there is an urgent need for more eicient screening tools to identify such vulnerable subjects or cases as early as possible to be able to beneit from considering drug treatment and changes towards healthier lifestyles (instead of considering surgical operations and other invasive treatment approaches). For example, a recent study showed that more than 50% of a group of randomly selected middle-aged individuals (that were apparently healthy) were actually sufering from subclinical atherosclerosis in the coronary or carotid arteries (without knowing about it). herefore, screening of the gen- eral population, especially middle-aged and elderly subjects, for cardiovascular diseases is proven to be controversial [8]. he degradation or lack of elasticity in arterial vessel walls (i.e., their stifness grade or severity) afects the blood pressure and low and is directly or indirectly related to other cardiovascular consequences and serious events. Myocardial infarction, let ventricular hypertrophy, and other serious cardiovascular diseases and deiciencies (as well as other Hindawi Publishing Corporation International Journal of Biomedical Imaging Volume 2014, Article ID 876267, 14 pages http://dx.doi.org/10.1155/2014/876267