title: Analysis of carotid artery plaque and wall boundaries on CT images by using a semi-automatic method based on level set model.
abstract: BACKGROUND
  The purpose of this study was to evaluate the potentialities of a semi-automated technique in the detection and measurement of the carotid artery plaque.
  
  
  METHODS
  Twenty-two consecutive patients (18 males, 4 females; mean age 62 years) examined with MDCTA from January 2011 to March 2011 were included in this retrospective study. Carotid arteries are examined with a 16-multi-detector-row CT system, and for each patient, the most diseased carotid was selected. In the first phase, the carotid plaque was identified and one experienced radiologist manually traced the inner and outer boundaries by using polyline and radial distance method (PDM and RDM, respectively). In the second phase, the carotid inner and outer boundaries were traced with an automated algorithm: level-set-method (LSM). Data were compared by using Pearson rho correlation, Bland-Altman, and regression.
  
  
  RESULTS
  A total of 715 slices were analyzed. The mean thickness of the plaque using the reference PDM was 1.86 mm whereas using the LSM-PDM was 1.96 mm; using the reference RDM was 2.06 mm whereas using the LSM-RDM was 2.03 mm. The correlation values between the references, the LSM, the PDM and the RDM were 0.8428, 0.9921, 0.745 and 0.6425. Bland-Altman demonstrated a very good agreement in particular with the RDM method.
  
  
  CONCLUSIONS
  Results of our study indicate that LSM method can automatically measure the thickness of the plaque and that the best results are obtained with the RDM. Our results suggest that advanced computer-based algorithms can identify and trace the plaque boundaries like an experienced human reader.
authors.affiliation: Department of Radiology, University of Cagliari-Azienda Ospedaliero Universitaria di Cagliari, Polo di Monserrato SS 554, Monserrato, Cagliari, Italy. lucasaba@tiscali.it
authors.forename: Luca
authors.initials: L
authors.lastname: Saba
authors.forename: Hao
authors.initials: H
authors.lastname: Gao
authors.forename: U Rajendra
authors.initials: UR
authors.lastname: Acharya
authors.forename: Stefano
authors.initials: S
authors.lastname: Sannia
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ledda
authors.forename: Jasjit S
authors.initials: JS
authors.lastname: Suri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001331:Automation; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods