Syngo arterial health package

Ultrasound was also used to assess DC (10⁻³ mmHg^-1), YEM (mmHg), and common carotid artery carotid intima-media thickness (IMT) [19 (link), 20 (link)]. Mean and maximal IMT of the far wall of distal CCA (distal 1 cm, proximal to the carotid bifurcation point, where the distal CCA diameter remains uniform) and the proximal 1 cm of the ICA were measured in triplicate at the University of Wisconsin using a semi-automated border detection program (Syngo Arterial Health package, Siemens Medical Solutions, Malvern, PA) blinded to subject demographic and medical information. For DC and YEM, systolic and diastolic diameters were determined as the largest and smallest diameters during the cardiac cycle. All measurements were performed in triplicate from 2–3 consecutive cardiac cycles to derive mean internal diameter at peak systole and mean internal and external diameters at end-diastole using Access Point Web version 3.0 (Freeland Systems, LLC) [20 (link)]. Thoracic aortic distensibility was measured with magnetic resonance imaging [21 (link)]; small and large artery elasticity were measured using radial pulse contour analyses [21 (link)]. Each of these measurements was calculated using standard formulae and have been previously described in detail within MESA [19 (link)–22 (link)].

All blood samples were obtained after 8 h of fasting, and subsequently analyzed. Height and weight were measured with the participants wearing light clothing and no shoes. Body mass index was calculated as weight (kg) divided by the square of height (m²). Carotid ultrasound was performed with a high-resolution B-mode ultrasonography system (Acuson X300; Siemens, USA) with a transducer frequency of 13–15 MHz. Computer-assisted acquisition, processing, B-mode image storage, and calculation of intima-media thickness were performed using the Syngo Arterial Health Package (Siemens, USA). Automatic measurements of both common carotid arteries were performed at the far wall of the 1-cm segment distal to the carotid bulbs. Carotid plaque was defined as the presence of focal wall thickening ≥ 50% than that of the surrounding vessel wall or as a focal region with a carotid intima-media thickness of ≥ 1.5 mm, protruding into the lumen and distinct from the neighboring boundary [18 (link), 19 (link)]. A representative image of a carotid plaque is presented in Fig. 1.Fig. 1

Representative image of a carotid plaque. The asterisk indicates a 1.0 × 0.3-cm plaque in the left internal carotid artery of a 54-year-old man