(B) The corresponding diagram shows the heel part of a heel-toe maneuver used to obtain this image. This leads to a loss of the lumen-intima interface but facilitates Doppler waveform analysis because the angle between artery and ultrasound probe has increased. The angle between the ultrasound beam and the walls of the common carotid artery is no longer 90 degrees. (A) Although the transducer is still in the axis of the artery, the transducer face has been angled by the heel-toe maneuver. These interfaces are lost if the transducer is not centered on the artery or if it is angled with respect to the long axis of the artery by a heel-toe maneuver ( Fig. The lumen-intima interface is best seen on longitudinal images when the image plane passes through the center of the artery and the ultrasound beam forms an incident angle of 90 degrees with the wall interfaces (see Fig. On transverse sections, clear visualization of the lumen-intima interface indicates that the image plane is perpendicular to the vessel axis. Significant undulation and thickening of the intima-lumen interface indicate advanced changes due to atherosclerosis (see Chapter 6 ) or, rarely, fibromuscular hyperplasia. In disease-free arteries, the intimal reflection should be straight, thin, and parallel to the adventitial layer. (B) As seen on the diagram, this view was achieved with the transducer surface parallel to the artery wall. This blends into the also echogenic peri-adventitial region.

The outermost echogenic ( white ) area is the adventitia of the artery. The black (relatively echolucent) region adjacent to this reflection represents the media of the artery ( arrowhead ). (A) This longitudinal image of the common carotid artery demonstrates a sharp line (specular reflection) that emanates from the intimal surface ( arrow ). There is a close correlation between histology and ultrasound-based measurements of the intima-media thickness (IMT).

In most instances, the lumen-intima interface is better appreciated on the far wall than for the near wall of the CCA, although this is likely ultrasound device dependent. What is seen is as a result of the reflection of the ultrasound beam at the lumen-intima interface, with the thickness corresponding roughly to the spatial resolution of the ultrasound probe. The thickness of the intima cannot be directly imaged on the B-mode ultrasound image because it typically measures 0.2 mm or less and is below the resolution of transcutaneous ultrasound, and the intima-media interface corresponding to the internal elastic lamina is not consistently visualized. The echogenic line seen at the transition between the media and the adventitia corresponds to the location of the external elastic lamina as seen on pathologic studies, while the internal elastic lamina is not discernable. In normal arteries, the interfaces between the lumen-intima and media-adventitia produce two parallel echogenic lines, with an intervening zone of low echoes that corresponds to the media. The three layers are discernable on B-mode (gray-scale) ultrasound images of the carotid arteries ( Fig.

It densely composed of fibroblasts and connective tissue. The transition zone in between, the carotid bulb, is the site predisposed to plaque formation with mixed morphometric components. It contains a preponderance of elastic and connective tissues in the common carotid artery (CCA), an elastic artery, whereas in the internal carotid artery (ICA), a muscular artery, there is a large proportion of smooth muscle cells intermixed with connective tissue. It is thin and is covered with a lining of endothelial cells. The intima is the innermost layer abutting the lumen. The carotid artery wall is composed of three layers: the intima, the media, and the adventitia. B-Mode Ultrasound of the Normal Carotid Artery Wall

Carotid doppler radiology