Variability of carotid artery measurements on 3-Tesla MRI and its impact on sample size calculation for clinical research

  • Mushabbar A. Syed
  • John N. Oshinski
  • Charles Kitchen
  • Arshad Ali
  • Richard J. Charnigo
  • Arshed A. Quyyumi
Original Paper


Carotid MRI measurements are increasingly being employed in research studies for atherosclerosis imaging. The majority of carotid imaging studies use 1.5 T MRI. Our objective was to investigate intra-observer and inter-observer variability in carotid measurements using high resolution 3 T MRI. We performed 3 T carotid MRI on 10 patients (age 56 ± 8 years, 7 male) with atherosclerosis risk factors and ultrasound intima-media thickness ≥0.6 mm. A total of 20 transverse images of both right and left carotid arteries were acquired using T2 weighted black-blood sequence. The lumen and outer wall of the common carotid and internal carotid arteries were manually traced; vessel wall area, vessel wall volume, and average wall thickness measurements were then assessed for intra-observer and inter-observer variability. Pearson and intraclass correlations were used in these assessments, along with Bland-Altman plots. For inter-observer variability, Pearson correlations ranged from 0.936 to 0.996 and intraclass correlations from 0.927 to 0.991. For intra-observer variability, Pearson correlations ranged from 0.934 to 0.954 and intraclass correlations from 0.831 to 0.948. Calculations showed that inter-observer variability and other sources of error would inflate sample size requirements for a clinical trial by no more than 7.9%, indicating that 3 T MRI is nearly optimal in this respect. In patients with subclinical atherosclerosis, 3 T carotid MRI measurements are highly reproducible and have important implications for clinical trial design.


3 Tesla MRI Carotid artery Reproducibility 


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Copyright information

© Springer Science+Business Media, B.V. 2009

Authors and Affiliations

  • Mushabbar A. Syed
    • 1
  • John N. Oshinski
    • 2
  • Charles Kitchen
    • 2
  • Arshad Ali
    • 3
  • Richard J. Charnigo
    • 4
  • Arshed A. Quyyumi
    • 3
  1. 1.Gill Heart InstituteUniversity of KentuckyLexingtonUSA
  2. 2.Department of RadiologyEmory UniversityAtlantaUSA
  3. 3.Division of CardiologyEmory University School of MedicineAtlantaUSA
  4. 4.Department of BiostatisticsUniversity of KentuckyLexingtonUSA

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