Evaluating carotid artery disease. The concordance between pulsed Doppler/spectrum analysis and angiography

The results of ultrasonic pulsed Doppler duplex scanning with spectral analysis and computer pattern recognition are compared with the results of contrast arteriography in patients screened for extracranial carotid artery disease. The intraangiographer variability (one radiologist reading the same films twice) and the interangiographer variability (two radiologists reading the same film independently) were also studied. To calculate degrees of agreement corrected for chance, the Kappa statistic was computed for all the evaluation methods employed. At the present time, the concordance between spectral analysis and cerebral contrast angiography reaches a Kappa value of 0.682 +/- 0.064. This level of agreement compares favorably with the interangiographer agreement level (K = 0.568 +/- 0.058) and the intraangiographer agreement (K = 0.711 +/- 0.054). The computer pattern recognition program predicted the degree of stenosis by angiography with an agreement of K = 0.721 +/- 0.059. This concordance compares favorably to that observed when the radiologists are compared with themselves and is greater than that reached by two different radiologists. The continuous improvement in precision and accuracy of duplex scanning offers the promise of its usefulness in clinical and epidemiological studies.