Ultrasound vascular screening for cardiovascular risk assessment. Why, when and how?
Carotid artery vessel wall assessment in the form of intima-media thickness (IMT) has been identified since the late 1970's as a sensitive tool to detect atherosclerosis, predict its sequelae and detect its progression and regression. Unfortunately the technique has remained confined to large multicenter clinical research trials and no consensus has been developed regarding methodology, analysis and interpretation and no agreed upon clinical protocol that could be used in clinical practice exists. The need for an accepted clinical protocol has become acute especially since the technique has been recommended by writing groups such as American Heart Association as a useful tool for risk stratification in those with unclear or intermediate risk of cardiovascular (CV) disease. The advent of automated edge detection software and a reimbursement of this technique by insurers make it compelling that clinical consensus is reached soon. Accurate data collection methodology and measurement precision are essential; as such a method that is sensitive yet not cumbersome is required for clinical utility. This review will give a short introduction to the studies that confirm value of IMT in detecting atherosclerosis and predicting its sequelae, followed by a discussion on the appropriate clinical method of imaging and reporting. Other controversial areas in methodology such as difference between plaque vs IMT in CV risk prediction will be discussed. Finally tools and skill a clinician will need to be able to do this technique will be discussed.