Ultrasound and Arterial Wall Disease

Abstract

Rapid progress in non-invasive ultrasound techniques has resulted in a wide variety of clinical applications for the assessment of cerebrovascular diseases. Recent highlights in ultrasound research include the evaluation of vascular ageing as a degenerative process, the demonstration of plaque development, motion and vulnerability in atherosclerosis and multi-dimensional as well as innovative imaging techniques (e.g., compound imaging) to depict early and small vascular lesions. In addition, echo-contrast agents have been used to compensate for difficulties in visualising late, severe or subtotal obstructive plaques, but failed to be really superior to conventional techniques as evidenced in a prospective, multi-centre trial (Contrast Enhanced Duplex sonography versus Arteriography Studies – CEDAS). With increasing sophistication of ultrasound methodology, it becomes essential to establish standards for data acquisition and interpretation: three consensus meetings have provided detailed recommendations on quantification of carotid atherosclerosis, characterisation of carotid artery plaques and detection of microembolism by transcranial Doppler as a potential indicator of stroke risk.

Ultrasound Measurement of the Fibrous Cap in Symptomatic and Asymptomatic Atheromatous Carotid Plaques

“…Whether differences in plaque echogenicity or surface morphology can predict the clinical expression of atheroma is still debated. 11 Recent studies have shown that high-resolution MRI can visualize FCT and rupture in vivo. 10 However, the availability of this technique is currently very limited, and the data obtained are qualitative and not quantitative.…”

“…11 The FC covered an area of weaker echoes that corresponded to lipid accumulation (lipid core). We have developed a system that finds the 2 paths within a specified area that best follow the hypoechogenic-hyperechogenic and hyperechogenichypoechogenic boundaries and then measures the distance between them ( Figure 2C).…”

“…Developments in ultrasound such as highresolution B-mode imaging, compounded imaging, measurement of shear stress, characterization of plaque motion, and 4D color Doppler flow imaging are promising diagnostic tools for carotid wall disease. 11 We evaluated the feasibility of measuring the FC thickness (FCT) of stenosing ICA plaques with a new semiautomated ultrasound system and investigated whether the obtained values could be used to discriminate symptomatic from asymptomatic atheromata.…”

Imaging Carotid Atherosclerosis Plaque Ulceration: Comparison of Advanced Imaging Modalities and Recent Developments

“…First, the overall accuracy of using B-mode sonography against criterion standard techniques (DSA or histopathology) is not high (sensitivity and specificity ranges from 39% to 89% and 72% to 87%, respectively). [27][28][29] Several studies have noted that its accuracy decreases with the increasing degree of stenosis, 30,31 and it has even failed to detect ulceration in high-grade stenosis. 29 The application of color-flow Doppler-assisted duplex imaging, which combines the B-mode and blood-flow velocity information, 32 also shows limitations in providing adequate information to identify plaque ulcerations.…”

Three-dimensional ultrasound scanning

“…Although many studies have validated the measurement of IMT, it is clear that many distinct biological pathways and mechanisms may be reflected by the measurement. For example, IMT may represent hypertensive medial hypertrophy [96,97], compensatory intimal thickening owing to mechanical forces of blood flow [98,99] or the initial 'fatty streak' stage of atherosclerosis that involves accumulation of macrophage foam cells in the artery wall [100].…”