For the US measurements, a GE Logic E9 US system (LOGIQ E9 XDclear 2.0 General Electric Medical Systems US, Wauwatosa, WI, USA) with linear transducer L2-9 MHz was used. For the aortic arch, a C1-6 MHz transducer was used. IMT was measured in common carotid artery (CCA), internal carotid artery (ICA), subclavian artery (SCA), axillar artery (AxA), common femoral artery (CFA), superficial femoral artery (SFA) and the aortic arch. Measuring principles are shown in Figure 1a . Both sides were investigated. The procedure has been described previously (28 (link)), with an addition of CFA and SFA in this study. For IMT measurements in CCA a 10 mm wide box was placed over the common carotid artery far wall, near (10 mm) the carotid bifurcation. A mean value of all measured far wall points in the box was presented. For validation of the method two repeated measurements were performed. Maximum systolic flow velocity was measured in all vessels to evaluate possible arterial stenosis. Plaques were defined as focal areas in the vessel wall where IMT showed increase of either 0.5 mm or 50% compared to the IMT in the adjacent wall.
In areas free of plaques with IMT ≥0.9 mm for carotid and central arteries, and ≥1.2 mm for the aortic arch, the vessel wall was assessed regarding echogenicity (low–medium–high). Furthermore, distribution and presence of fibrotic stripes were noted. The cutoff value of ≥0.9 mm was chosen due to the latest European Society of Hypertension/European Society of Cardiology (ESH/ESC) hypertension guidelines (29 (link)). For the aortic arch a higher cutoff value was chosen due to generally higher aortic arch IMT values among our healthy controls, according to results from earlier studies (30 (link)). Plaques were assessed regarding echogenicity (low–medium–high), distribution, irregularity (homogenicity or heterogenicity) and cap (smooth surface or ulceration).
A standardized examination procedure was used in all individuals. The participant had to rest 15 min before the test which was performed in a room with a temperature of 25°C, dim lighting and no outer disturbances. All participants were asked to refrain from coffee 4 h prior to the measurements.
The same vascular sonographer performed all US examinations and offline measurements performed after the exam. The sonographer was blinded to which classification criteria the patients with SLE fulfilled, but not blinded to whether the participants were patients or controls.
In areas free of plaques with IMT ≥0.9 mm for carotid and central arteries, and ≥1.2 mm for the aortic arch, the vessel wall was assessed regarding echogenicity (low–medium–high). Furthermore, distribution and presence of fibrotic stripes were noted. The cutoff value of ≥0.9 mm was chosen due to the latest European Society of Hypertension/European Society of Cardiology (ESH/ESC) hypertension guidelines (29 (link)). For the aortic arch a higher cutoff value was chosen due to generally higher aortic arch IMT values among our healthy controls, according to results from earlier studies (30 (link)). Plaques were assessed regarding echogenicity (low–medium–high), distribution, irregularity (homogenicity or heterogenicity) and cap (smooth surface or ulceration).
A standardized examination procedure was used in all individuals. The participant had to rest 15 min before the test which was performed in a room with a temperature of 25°C, dim lighting and no outer disturbances. All participants were asked to refrain from coffee 4 h prior to the measurements.
The same vascular sonographer performed all US examinations and offline measurements performed after the exam. The sonographer was blinded to which classification criteria the patients with SLE fulfilled, but not blinded to whether the participants were patients or controls.
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