This chapter discusses the clinical merits and limitations of conventional ultrasound (US) techniques for evaluation of both early and advanced carotid disease. A number of complementary ultrasonographic techniques such as B-mode scanning, duplex sonography, and contrast harmonic imaging are available for imaging of the carotid arteries. The first morphological abnormalities of arterial walls can be imaged by B-mode ultrasonography. This technique is one of the best methods for detection of early stages of atherosclerotic disease, because it is easily applicable, readily available, and demonstrates the wall structure with better resolution than magnetic resonance angiography or conventional angiography. In the initial period of cerebrovascular ultrasonographic insonation, the ophthalmic artery was used as an indirect test for detection of significant carotid artery stenosis. Targeted US techniques combine US imaging technology with specific contrast agents for the assessment of molecular or genetic signatures for disease.

This chapter focuses on the algorithms implemented in CASCADE to perform the four principal processing steps in carotid plaque characterization. It presents an overall framework for measuring the volumes of atherosclerotic plaque components in the carotid artery. To evaluate the effects of plaque composition on outcome, noninvasive imaging techniques must be paired with algorithms to segment the plaque into its constituent components and quantify the relative amounts of each. The extent of high-density regions in computed tomography (CT) images of vessel walls is associated with the extent of calcification, and can be used as a risk factor for heart attack and stroke. The image processing challenge for measuring morphological indices of atherosclerotic plaque is one of boundary detection. From the lumen and wall boundaries, a number of morphological indices can be derived. These include the minimal lumen area, maximal wall area, total wall volume, and maximal wall thickness.