Iu22 ultrasound machine

Endothelial function was measured by a single operator using flow-mediated dilatation (FMD) as described previously42 (link). Briefly, subjects were fasted overnight and rested in a temperature-controlled room. A blood pressure cuff was placed on the forearm and inflated to supra-systolic pressure for 5 minutes. The brachial artery was visualised using a Philips iU-22 ultrasound machine and the diameter was measured off-line on a frame-by-frame basis for a period of 2 minutes. The mean maximal diameter was calculated using a cubic spline curve. FMD was defined as the % change in diameter between baseline and mean maximal diameter. Dilatation was also measured in response to sublingual glyceryl trinitrate (GTN). Endothelial function was expressed as the ratio of endothelial-dependent (FMD) to endothelium-independent (GTN-mediated) dilatation (ED/EI) in order to correct for differences in baseline arterial diameter and subject age.

All ultrasound examinations were carried out by the same ultrasonographer, who had more than 15 years of experience in vascular ultrasonography. CIMT was evaluated by high-resolution B-mode ultrasonography using a Philips iU22ultrasound machine equipped with a 3–9 MHz linear array probe (Philips Healthcare, USA). Mean CIMT was automatically measured (by the IU22 system) at a plaque-free site in the far wall of the common carotid artery 1–2 cm below its bifurcation. CIMT was measured on both sides, and the higher value was selected as the value to be used in the analysis.
The bilateral internal carotid arteries were also evaluated for the presence of plaques. A plaque was defined as a maximal IMT ≥1.5 mm (27 (link)). For the analysis, each patient was classified as either having a plaque (one or more plaques detected in the internal carotid artery on at least one side) or plaque-free (no plaques detected on either side).

FMD was evaluated within 2 days from the screening visit by an experienced angiologist blinded to other clinical data. All participants were studied in the morning beginning between 8:00 and 9:00 am, fasting, and having avoided alcohol for at least 24 h and caffeine for at least 12 h. Vasoactive and non-steroidal anti-inflammatory medications were withheld for 48 h before the test. Subjects rested supine in a quiet, temperature-controlled environment for 20 min before the exam. The right brachial artery was imaged in the longitudinal plane 2 to 15 cm proximal to the antecubital fossa using a 17–5 MHz linear array transducer connected to an iU22 ultrasound machine (Philips Medical Systems, Monza, Italy). Depth and gain were selected to enable optimal identification of the anterior and posterior intimal interface between lumen and vessel wall on 2D grayscale images. Baseline images were then acquired. Blood flow was measured from the pulsed wave Doppler signal with a 60° insonation angle. After recording baseline values, a sphygmomanometer cuff was applied around the forearm, inflated to 250 mmHg, and left in place for 5 min, causing forearm ischemia and consequent dilation of downstream resistance vessels. Blood flow was measured over the first 15 s after cuff deflation, whereas arterial images were acquired between 60 and 90 s after cuff release (22 (link)).

Ultrasound perfusion imaging was performed by a dedicated study team who were not masked for clinical course. The transcranial color duplex sonography was performed with a 1–5 MHz dynamic sector array (S5-1) from a Philips iU22 ultrasound machine (Philips Healthcare, Andover, MA). The field-of-view was set to an imaging depth of 150 mm in a sector angle of 90°. The imaging plane was then tilted to the diencephalic plane as described before, in which the frontal horns of the side ventricles and the third ventricle serve as landmarks and where the anterior and posterior middle cerebral artery (MCA) territory and the basal ganglia (BG) as region of interest could be identified without artifacts from major vessels [14 (link)]. High mechanical index bolus imaging was performed from both sides individually [14 (link)]. Data acquisition of 45 s was started immediately after intravenous (i.v.) injection of a 2-ml bolus of the second-generation contrast enhancer SonoVue (Bracco International, Milano, Italy), followed by a 10-ml flush of saline using an mechanical index (MI) setting of 1.34 and a frame rate of 5 Hz.