Medical Imaging in Clinical Trials by Colin G. Miller Joel Krasnow & Lawrence H. Schwartz

Author:Colin G. Miller, Joel Krasnow & Lawrence H. Schwartz
Language: eng
Format: epub
Publisher: Springer London, London

Carotid Ultrasound

Carotid atherosclerosis has proved to be a useful surrogate for coronary atherosclerosis in epidemiological and prospective interventional trials of anti-atherosclerotic agents. Since similar pathophysiological mechanisms are present in both the coronary and carotid arteries, imaging of the carotid arteries has been used as a gauge of pharmacologic activity on atherosclerotic progression. Ultrasonography permits noninvasive detection and quantification of abnormalities of carotid arterial structure, including wall thickening, plaque formation, and lumen enlargement. High-resolution B-mode ultrasound permits accurate and reproducible identification and measurement of the combined thickness of the intimal and medial layers of the carotid artery (Fig. 9.7). Several large epidemiological studies have shown significant associations between carotid intima-media thickness (CIMT) and both prevalent and incident coronary and cerebrovascular disease. Accordingly, measurement of CIMT has been a mainstay of cardiovascular epidemiological research for more than two decades. When scanning and reading are performed carefully, the reproducibility and reliability of CIMT measurement can be excellent. Cross-sectional analyses suggest that age-related increases in mean CIMT average approximately 0.010 mm/year for women and 0.014 mm/year for men in the internal carotid artery and 0.010 mm/year for both genders in the common carotid artery. Similar values have been observed in prospective studies. Because the magnitude of clinically relevant differences in percentiles of CIMT and the progression rates are close to the resolution of vascular ultrasound transducers, highly standardized protocols are needed for performing and interpreting studies, which underscores the importance of high-quality, detailed image-acquisition protocols and highly skilled and trained ultrasonographers.

Fig. 9.7Ultrasound in carotid anatomy. Ultrasound images used for the determination of carotid anatomy in a subject. The panel on the left shows an image of the right carotid artery used to determine intima-media thickness (IMT), with the arrows at the far carotid wall showing where IMT was determined. The panel on the right shows an image used to determine total plaque volume (TPV), with the encircled colored region defining one of the plaques identified (From Pollex et al. [12]. © 2006 ; licensee BioMed Central Ltd; http://​www.​cardiovascularul​trasound.​com/​content/​4/​1/​28)

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