ABC | Volume 112, Nº6, June 2019

Statement Vascular Ultrasound Statement from the Department of Cardiovascular Imaging of the Brazilian Society of Cardiology – 2019 Arq Bras Cardiol. 2019; 112(6):809-849 2.2. Ultrasound Definition of Intima-media Thickness and Carotid Plaque In two-dimensional images, IMT is characterized by a double line with defined intima-lumen and media-adventitia interfaces. IMT is the distance between the two acoustic interfaces. The atheromatous carotid plaque (CP) can be defined as a focal structure that spreads at least 0.5 mm into the arterial lumen, and/or measures more than 50% of the surrounding IMT value, and/or has an IMT > 1.5 mm. 9 Figure 1 schematically illustrates the IMT measurement and the three ways to define CP. 2.2.1. Indications The European and American consensuses 9,10 recommend measuring IMT in specific groups (Table 1). In these groups of individuals, IMT is considered increased when above the 75 percentile for their age, gender, and ethnicity, according to one of the normative tables, assisting in the discussion of clinical treatment and change in lifestyle. If a CP is found, regardless of the obstruction degree, IMT measurement does not need to be reported, except for exams explicitly requested for this purpose. In these cases, if the CP is located in the IMT measurement, it should be included in the value. 2.2.2. Measurement Protocol The recommended protocol is similar to the one described by the ELSA-Brasil study 13 (Table 2). After collecting numerical IMT data, the average values will be compared with existing reference numbers, according to normative tables of the studies ELSA Brasil, 13 CAPS, 14 or MESA. 15 The decision about which table to use will depend on the gender, age, and ethnicity of the individual. Although the manual point-to-point measurement is less reproducible – considering the differences in ultrasound equipment used in our country –, the consensus was that it could be used if the equipment does not automatically measure IMT, strictly respecting the technical recommendations. The examiner should pay special attention when placing the cursor in the intima-lumen and media-adventitia interfaces and be very cautious not to overestimate the values. In this case, measure each side at least five times to obtain the mean value (mean IMT). 16 2.2.3. Interpretation of Results Mean IMT [mean of measurements in the right or left common carotid artery (RCCA and LCCA, respectively)]: most types of equipment provide this measurement automatically or semi-automatically (in the latter case, the examiner can make small adjustments based on the automatic one). After calculating the mean IMT values from each side, compare them to the table to find the equivalent percentile. The individual under study is classified in the highest percentile. To determine the percentile of IMT measurement, consult tables 3 to 5, according to the age group of the individual under study. 2.2.4. How to Prepare a Report Describe the mean IMT on each side, in mm, in the body of the report. Also, include in conclusion if the value is Figure 1 – Schematic illustration showing examples of IMT and plaque measurements. IMT measurement (A). Different measurements of 3 carotid plaques: encroaching ≥ 0.5 mm on the arterial lumen (B); measurement > 50% of the surrounding IMT value (C); large plaque (D). 813