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22 | Chapter 2 Systems, Bothell, USA(7)), equipped with an L9-3 transducer, which used the automated QLAB IMT plugin for C-IMT measurements. Carotid ultrasound acquisition All images were acquired based on the ‘American Society of Echocardiography consensus statement’ protocol (8). In short, subjects were examined lying on an even surface with their head positioned in an angle of approximately 45 degrees facing left when measuring the right side, and vice versa, while performing the ultrasound acquisition. Carotid ultrasound analysis The mean C-IMT was measured over a length of 1 cm, at least 0.5 cm proximal of the bifurcation in the common carotid artery. Both sides were measured from two angles: anterior (170°-190°), and lateral (right: 120°-145°; left: 210°-235°). A plaque scan was performed by placing the transducer transversally in the neck, visualizing the internal, external and common carotid artery. A plaque was marked as present only if the local IMT was more than 50% of the surrounding IMT, or if the C-IMT was above 1.5 mm (9). Intra-observer and inter-observer variability For the intra-observer variability the result section of the CHS monitor was covered so that the results were not visible for the observer. After the first procedure the patient was asked to stand up, was then repositioned, and finally re-measured. The inter-observer variability was assessed by measuring patients twice in succession. First, one of the observers measured the subject whilst the other observer was in the next room. After the first observer finished the procedure the other observer was summoned and subsequently performed the second measurement. From the acquired data we used the individual measurements at the four scan positions, as well as the C-IMT per patient.