title: Automated measurement of mean wall thickness in the common carotid artery by MRI: a comparison to intima-media thickness by B-mode ultrasound.
abstract: OBJECTIVE
  To determine whether the mean wall thickness (MWT) of the common carotid artery (CCA) measured by MRI is comparable to B-mode ultrasound (US) measurement of the intima-media thickness (IMT), an established marker of cardiovascular risk.
  
  
  METHODS
  As part of the two-year ORION trial, 43 patients with 16-79% stenosis by duplex US underwent high-resolution MRI and B-mode US examinations of their carotid arteries. Twenty-eight carotid arteries were identified as having both sufficient proximal coverage and adequate image quality of the CCA on MRI and a corresponding US. A novel algorithm utilizing statistical shape modeling was developed to automatically detect and measure MWT to within subpixel accuracy. The interrater and interscan reproducibility of the MWT measurement was computed as the root-mean-square (RMS) difference. The MWT and IMT measurements were compared via the Pearson correlation coefficient.
  
  
  RESULTS
  The MWT and IMT had a high Pearson correlation coefficient (r = 0.93; P < 0.001). The RMS difference between readers and between scans was 0.01 mm and 0.04 mm, respectively. Our automated algorithm correctly identified the lumen in 28 cases (100%) and the outer-wall boundary in 26 cases (93%).
  
  
  CONCLUSIONS
  Automated measurements of the MWT by MRI are reproducible and have a high correlation with the IMT by B-mode US.
authors.affiliation: Department of Radiology, University of Washington, Seattle, Washington 98109, USA. hunterru@gmail.com
authors.forename: Hunter R
authors.initials: HR
authors.lastname: Underhill
authors.forename: William S
authors.initials: WS
authors.lastname: Kerwin
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hatsukami
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
mesh_terms: D000368:Aged; D001161:Arteriosclerosis / Q000000981:diagnostic imaging / Q000473:pathology*; D001331:Automation; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology*; D019160:Endosonography / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000473:pathology*; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000473:pathology*