title: Assessment of carotid stiffness and intima-media thickness from ultrasound data: comparison between two methods.
abstract: OBJECTIVE
  Increased arterial stiffness and carotid intima-media thickness (IMT) are considered independent predictors of cardiovascular events. The aim of this study was to compare a system recently developed in our laboratory for automatic assessment of these parameters from ultrasound image sequences to a reference radio frequency (RF) echo-tracking system.
  
  
  METHODS
  Common carotid artery scans of 21 patients with cardiovascular risk factors and 12 healthy volunteers were analyzed by both devices for the assessment of diameter (D), IMT, and distension (DeltaD). In the healthy volunteers, analyses were repeated twice to evaluate intraobserver variability. Agreement was evaluated by Bland-Altman analysis, whereas reproducibility was expressed as a coefficient of variation (CV).
  
  
  RESULTS
  Regarding the agreement between the two systems, bias values +/- SD were 0.060 +/- 0.110 mm for D, -0.006 +/- 0.039 mm for IMT, and -0.016 +/- 0.039 mm for DeltaD. Intraobserver CVs were 2% +/- 2% for D, 5% +/- 5% for IMT, and 6% +/- 6% for DeltaD with the RF echo-tracking system and 2% +/- 1% for D, 6% +/- 6% for IMT, and 8% +/- 6% for DeltaD with our automated system.
  
  
  CONCLUSIONS
  Although B-mode-based devices are less precise than RF-based ones, our automated system has good agreement with the reference method and comparable reproducibility, at least when high-quality images are analyzed. Hence, this study suggests that the presented system based on image processing from standard ultrasound scans is a suitable device for measuring IMT and local arterial stiffness parameters in clinical studies.
authors.affiliation: Institute of Clinical Physiology, National Research Council, Pisa, Italy. betta@ifc.cnr.it
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bianchini
authors.forename: Erwan
authors.initials: E
authors.lastname: Bozec
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Gemignani
authors.forename: Francesco
authors.initials: F
authors.lastname: Faita
authors.forename: Chiara
authors.initials: C
authors.lastname: Giannarelli
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Ghiadoni
authors.forename: Marcello
authors.initials: M
authors.lastname: Demi
authors.forename: Pierre
authors.initials: P
authors.lastname: Boutouyrie
authors.forename: Stéphane
authors.initials: S
authors.lastname: Laurent
mesh_terms: D000293:Adolescent; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017539:Tunica Intima / Q000000981:diagnostic imaging* / Q000502:physiology*; D017540:Tunica Media / Q000000981:diagnostic imaging* / Q000502:physiology*