Relative accuracy of the diagnostic components of noninvasive carotid arterial tests: a comparison of pulsed Doppler arteriography and spectrum analysis.

Pulsed Doppler ultrasonography (UA), sound spectrum analysis, and subjective interpretation of the audible signal are valuable methods for assessing carotid arterial disease; however, the relative contribution of each in making a diagnosis is disputed. To investigate this issue, 258 noninvasive carotid studies with measured x-ray comparisons were reviewed. Internal carotid spectra, UA images, and images combined with the technician's comments were each interpreted blindly by three independent readers. Percentage of stenosis was categorized into six groups: 0, 1% to 24%, 25% to 49%, 50% to 74%, 75% to 99%, and 100%. Each reader's assessment of the individual noninvasive components and his overall reading of the complete study were compared with x-ray findings and with those of the other two readers. The readings of the three observers were consistent within each diagnostic component (p less than 0.001). For each reader, the technician's comments significantly improved the accuracy of ultrasonic imaging alone (p less than 0.001). Spectrum analysis was as good as the image plus technician's comments and, for two of three readers, was better than the image alone (p less than 0.001).

Computerized multiplanar imaging and lumen area plotting for noninvasive diagnosis of carotid artery disease.

Some of the errors associated with pulsed Doppler imaging of the carotid bifurcation relate to the fact that the vessels are usually viewed in only one plane. To reduce these projection errors, a computerized ultrasonic arteriograph (CUA) was developed, which simultaneously produces lateral and anteroposterior images of the carotid bifurcation together with a histogram that depicts the cross-sectional area of the lumen at 1 mm points along the vessel. The area measured from the histogram and that estimated from biplanar arteriograms agreed in 46/57 (81%) of the internal carotid arteries studied by both techniques. The area histogram was positive for 91% of the arteries with arteriographically visible disease and was 79% specific for eliminating the presence of disease. The combined CUA study (histogram plus images) had a sensitivity and specificity of 96% and 80% for detecting any disease, 96% and 92% for evaluating diameter stenoses of 20%, and 89% and 98% or evaluating stenoses of 40%. These preliminary results suggest that the CUA may enhance the accuracy of pulsed Doppler imaging.