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 based on recommendations from the DCI panel of experts in 2015 and 2016. 1,2 This guideline does not aim to compare VUS with other imaging examination methods or expound on the use of VUS in the follow-up of vascular diseases after the initial diagnosis. For this content, the reader should consult more extensive and specific publications on the subject. Our goal is to disseminate the best practices in VUS to various services in the country, standardize the interpretation of examinations, and contribute to the proper use of this non- invasive, widely available, and low-cost tool. 1.2. Equipment In a country with continental dimensions and different economic realities like Brazil, it is difficult to determine what ideal equipment is. We cannot demand from a small laboratory in the interior of the country to work with equipment that has the same technological resources needed for a laboratory that assists a large number of patients. This standardization intends to suggest the appropriate minimum resources of equipment and the ideal way to perform, with safety and accuracy, the examinations whose protocols will be described below, always remembering that this area is in constant evolution. 1.2.1. Machine The equipment must be capable of delivering the following types of image and Doppler: (a) two-dimensional image; (b) color flow imaging (CFI); (c) pulsed wave Doppler; (d) continuous wave Doppler (for some types of transducers, but not required for vascular examinations); (e) power Doppler, also known as power angio and Doppler energy – way of mapping the flow without indicating the direction, based on the amplitude of the signal (ideal resource, but not essential to the examination). More advanced tools, such as second-harmonic imaging, B-Flow, inversion recovery pulse sequences – for the use of microbubble contrast –, and even transducers capable of producing three-dimensional images, are useful in complex examinations, but not yet part of our daily practice. They will also be covered for information purposes as a way to encourage the technological progress that brings additional benefits to patients. 1.2.2. Applications (Software) Among the application options, the equipment must have specific presets to each type of study to expedite and facilitate the task of the examiner. 1.2.3. Multi-frequency or Broadband Transducers • Linear transducer : ideal frequency between 5 and 10 MHz (in some cases, frequencies of 4 or 12 MHz can be useful); for studies of superficial structures, since transducers of higher frequency have better axial image resolution, but their use is limited due to the large sound damping when traveling through tissues. • Convex transducer : ideal frequency between 2 and 5 MHz; used in studies of deeper structures, such as abdominal ones, with the advantage of covering a larger area compared to sector transducers of similar frequencies. • Low-frequency sector transducer : 2 to 4 MHz; useful when the examiner needs continuous Doppler in studies of abdominal arteries. • High-frequency sector transducer : 4 to 10 MHz; useful when the acoustic window is limited by bone structures. • Micro-convex transducer : frequency between 4 and 8 MHz; adaptable to sites with limited window, such as bone structures, dressings, wounds, or other situations in which the contact surface available for the probe is reduced, without loss of lateral resolution in distal fields, as presented by sector transducers. 1.2.3.1. Image Orientation In longitudinal images, most vascular imaging guides recommend displaying cranial structures on the left side of the screen, and caudal structures on the right. In transverse planes, structures on the left side of the screen must correspond to the marking on the upper left corner of the monitor. That way, transverse planes will display right lateral structures, as well as left medial structures on the left side of the monitor screen. 3,4 2. Carotid and Vertebral Arteries According to the World Health Organization (WHO), CVDs are the main causes of morbidity and mortality worldwide. In 2012, 17.5 million people died from CVDs, the equivalent to 31% of all deaths occurred in the period, with estimates that 7.4 million resulted from coronary artery disease (CAD) and 6.7 million from cerebrovascular accident (CVA). 5 Ultrasound of carotid arteries is valuable and widely used in cardiovascular risk assessment, as it measures the intima-media thickness (IMT), detects atherosclerotic plaques, and can evaluate the morphology of plaques and degree of stenosis, characteristics associated with cerebrovascular events. 2.1. Intima-media Thickness and Detection of Carotid Artery Plaques for Cardiovascular Risk Assessment With the publication of the Brazilian Guidelines for Dyslipidemia and Atherosclerosis Prevention in 2007 and 2013, 1,6-8 the Mannheim consensus documents of 2004-2011, 9 and the American Society of Echocardiography consensus, 10 Brazilian experts in the VUS field joined forces to disseminate the correct way to measure IMT and detect atherosclerotic plaques in carotid arteries. In the latest update of the Brazilian guideline in 2017, 8 IMT measurement was not included separately in the stratification of cardiovascular risk, but in the characterization of atherosclerotic plaque as IMT > 1.5 mm. Another aspect that shows the importance of correctly measuring IMT is its use in several research protocols. Since the American and European expert consensuses use IMT as an aggravating factor for cardiovascular risk, we decided to include the measurement technique in this guideline. This section aims to standardize the technique to measure IMT and detect carotid plaques. 812