Quantification of extracranial carotid artery stenosis by ultrafast three-dimensional ultrasound.

This study was designed to evaluate the possible contribution of 3-dimensional (3D) ultrasound (US) for noninvasive detection of extracranial carotid artery stenosis. Sixty-nine stenotic lesions of extracranial carotid artery were studied by (1) B-mode (Bm) US, (2) Doppler spectral analysis, and (3) a prototype of 3D vascular system. When indicated (46 stenotic lesions), biplane carotid angiography (CA) was performed. The degree of luminal narrowing measured as percent area reduction in the 3D data set correlated well with the degree of stenosis estimated by CA (r = 0.79, P <.01, mean difference 7.8% +/- 15.5%); however, for stenosis between 40% and 70%, 3D US tended to give higher values. Compared with CA, the sensitivity, specificity, diagnostic accuracy, and positive predictive value of 3D US for significant (> or =70%) stenosis were 96.0%, 77.7%, 88.3%, and 85.7%, respectively. Thus, 3D US showed good sensitivity and diagnostic accuracy for detection of significant stenosis of extracranial carotid artery. For stenosis between 40% and 70%, 3D US indicated a higher degree than CA; this finding suggests that CA may underestimate the severity of stenosis due to known discrepancies between linear measurement and true anatomic situation.

Ultrafast three-dimensional ultrasound: application to carotid artery imaging.

BACKGROUND AND PURPOSE: Three-dimensional (3-D) vascular ultrasound can be expected to improve qualitative evaluation of vessel pathology and to provide quantitative data on vascular morphology and function. The objective of this study was to develop an ultrafast 3-D vascular system and to validate its performance for quantitation of atherosclerosis and assessment of regional arterial distensibility. METHODS: The quantitative analysis of focal atherosclerotic lesions was validated in vitro on 27 phantoms of fibroadipous plaques of known volume (range, 100 to 600 mm3). In vivo reproducibility of plaque volume measurement was tested in 33 patients who had a total of 47 predominantly fibroadipous carotid plaques. Distensibility assessment was validated indirectly through the evaluation of age-related changes in distensibility of common carotid artery in healthy and hypertensive subjects (25 men in each group). RESULTS: The volume of plaque phantoms measured from the 3-D data set showed a very close correlation with the true volume (r=0.99; y=0.96x+12.38; P<0.01), with the mean difference between the 2 measurements being -3.12+/-15.1 mm3. High reproducibility was found for measurement of carotid plaque volume in vivo: the mean difference between measurements from 2 observers for the same data set was 0.60+/-11.2 mm3. Indexes of arterial distensibility decreased with age in healthy population, whereas this relationship was lost in hypertensive subjects. CONCLUSIONS: Ultrafast 3-D ultrasound imaging of carotid artery demonstrates good accuracy and reproducibility for atherosclerotic plaque volume measurements. The system also allows the study of age-related degenerative vascular changes.