The accuracy of duplex scanning in the evaluation of early carotid disease.

The accuracy of duplex scanning in 69 comparisons with biplanar angiography in the detection of early carotid disease has been assessed. The various criteria reported for the categorisation of less than 50% disease have been critically analysed. As part of the study, 50 internal carotid arteries of 25 young, presumed normal medical students of mean age 20 years have been examined. The results suggest that duplex scanning has the ability to grade less than 50% carotid disease into normal, 1-24% and 25-49% stenosis categories. The most sensitive indicator of early disease is obtained from the real-time B-scan. The waveform changes of the maximum frequency envelope were more sensitive than spectral broadening except where full spectral broadening was present. For confident assessment, the real-time B-scan and pulsed Doppler must always be used in conjunction.