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24 | Chapter 2 Figure 2.1b | Image output of the C-IMT measurement of the two different systems. Longitudinal view of the common carotid artery and bifurcation. On the left side of the images the widening of the artery suggest the bifurcation where the“arteria carotis communis”splits into the “arteria carotis inerna”, and the “arteria carotis externa”. CHS: Panasonic CardioHealthStation; PiU: Philips iU-22 ultrasound system. Statistics Binary variables were expressed as number (percentage), and continuous variables as mean ± standard deviation. For C-IMT, the intra-class coefficient (ICC) and Bland Altman analyses were used to determine the mean difference within and between the observers. The ICC was expressed as mean (95% CI). The results of the Bland-Altman analyses were expressed as the limits of agreement (LOA) as mean ± standard deviation. The LOA expresses the difference between the two measurements and a one sample t-test was used to test for statistical significance. The inter-observer variability was determined on the individual C-IMT measurements, and on the mean C-IMT of a subject. The association between the differences in C-IMT measurements and the mean C-IMT was determined by linear regression. Agreement in plaque identification between observers and systems was expressed by the Kappa statistic. All statistical analyses were performed using SPSS version 21 (SPSS Inc., Chicago, IL, USA). Results In total 85 subjects were examined in this study. For determination of intra-observer variability, observer X scanned 15 patients and observer Y 15 other patients; 40 patients CHS PiU