Symptomatic vs. Asymptomatic Plaque Classification in Carotid Ultrasound

  • Authors:
  • Rajendra U. Acharya;Oliver Faust;A. P. Alvin;S. Vinitha Sree;Filippo Molinari;Luca Saba;Andrew Nicolaides;Jasjit S. Suri

  • Affiliations:
  • Department of ECE, Ngee Ann Polytechnic, Singapore, Singapore 599489;Aberdeen University, Aberdeen, Scotland;Department of ECE, Ngee Ann Polytechnic, Singapore, Singapore 599489;School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore, Singapore 639798;Biolab, Department of Electronics, Politecnico di Torino, Torino, Italy;Department of Radiology, A.O.U Cagliari, Polo di Monserrato, Italy;Vascular Screening Diagnostic Center Nicosia, Nicosia, Cyprus;Biomedical Technologies Inc., Denver, USA and Idaho State University (Aff.), Pocatello, USA

  • Venue:
  • Journal of Medical Systems
  • Year:
  • 2012

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Abstract

Quantitative characterization of carotid atherosclerosis and classification into symptomatic or asymptomatic type is crucial in both diagnosis and treatment planning. This paper describes a computer-aided diagnosis (CAD) system which analyzes ultrasound images and classifies them into symptomatic and asymptomatic based on the textural features. The proposed CAD system consists of three modules. The first module is preprocessing, which conditions the images for the subsequent feature extraction. The feature extraction stage uses image texture analysis to calculate Standard deviation, Entropy, Symmetry, and Run Percentage. Finally, classification is performed using AdaBoost and Support Vector Machine for automated decision making. For Adaboost, we compared the performance of five distinct configurations (Least Squares, Maximum- Likelihood, Normal Density Discriminant Function, Pocket, and Stumps) of this algorithm. For Support Vector Machine, we compared the performance using five different configurations (linear kernel, polynomial kernel configurations of different orders and radial basis function kernels). SVM with radial basis function kernel for support vector machine presented the best classification result: classification accuracy of 82.4%, sensitivity of 82.9%, and specificity of 82.1%. We feel that texture features coupled with the Support Vector Machine classifier can be used to identify the plaque tissue type. An Integrated Index, called symptomatic asymptomatic carotid index (SACI), is proposed using texture features to discriminate symptomatic and asymptomatic carotid ultrasound images using just one index or number. We hope this SACI can be used as an adjunct tool by the vascular surgeons for daily screening.