Over the last two decades, B-mode ultrasound has been increasingly used to detect both early and advanced carotid atherosclerosis. In clinical practice, duplex ultrasound allows accurate measurement of the degree of lumen stenosis, which is the parameter used to select patients for carotid surgery. On the other hand, epidemiological studies have focused on the evaluation of carotid intima-media thickness (IMT), a valid and reliable measure of arterial wall atherosclerotic disease [1]. Carotid IMT measurements have been shown to correlate with atherosclerotic lesions in other vascular territories [2,3] and have been related to clinical events such as transient ischemic attacks and stroke in population-based prospective studies [4-6]. Although the value of carotid IMT as a quantitative indicator of atherosclerotic burden in epidemiological studies is without debate, in daily practice measurement of carotid IMT is still not easily performed. Indeed, clinical data on carotid IMT measured in patients admitted to the hospital for cerebrovascular accidents are scarce [7,8].

Our Study

Our recent study [9] was designed to measure carotid IMT in a sample of consecutive patients (mean age 66 years) with a recent ischemic cerebrovascular accident, referred for endarterectomy on the basis of a tight angiographic stenosis. To provide valid data, a gold standard, i.e. the anatomic pathology, was used and a control group consisting of 24 carotid arteries dissected from deceased persons, who died from documented causes unrelated to cerebrovascular disease, was analyzed.

The thickest IMTs in specimens from symptomatic patients were located in the internal carotid (mean 3.6 ± 1.5 mm).

Using a logistic model, we defined a maximum IMT cut-off value of 2.33 mm for the common carotid, 2.45 mm for the bifurcation, and 2.23 for the internal carotid as associated with a high probability of a cerebrovascular ischemic accident. This is the first study to provide a cut-off of carotid IMT in neurologically symptomatic patients undergoing endarterectomy. The relationship between carotid IMT and the degree of stenosis is still to be defined in a larger study group.

In our study, ROC curve analyses demonstrated that the diagnostic ability of IMT measurements performed at the level of internal carotid artery to separate cases from controls was greater than common carotid artery or bifurcation measurements. A growing number of research studies using B-mode ultrasound focused only on the IMT of the common carotid artery, which is regarded as a marker of generalized atherosclerosis. Actually, no consensus has been developed concerning an ultrasonographic protocol that can be used in routine clinical practice.

Our results suggest that IMT measurements of the internal carotid artery and bifurcation should be included in ultrasound protocols used in clinical practice, since these segments appear to be the most powerful indicators of atherosclerotic clinical sequelae.