Duplex ultrasound and ocular pneumoplethysmography concordance in detecting severe carotid stenosis
J. E. Castaldo, G. G. Nicholas, W. Gee and J. F. Reed
Division of Neurology, Allentown Hospital-Lehigh Valley Hospital Center, PA 18103.
Concordance between two independent tests should serve to increase the
accuracy of diagnosis. A combination of ocular pneumoplethysmography and
duplex ultrasound, which uses high-resolution B-mode imaging plus spectral
analysis, was used to evaluate 289 consecutive patients prior to biplane
carotid angiography. Where there was concordance, the noninvasive tests
predicted the presence or absence of hemodynamically severe carotid
stenosis (75% or greater cross-sectional area reduction) with a sensitivity
of 96.8%, a specificity of 95.9%, an accuracy of 96.2%, and positive and
negative predictive values of 91.0% and 98.6%, respectively. Of the 538
study arteries, only four (0.74%) angiographically severe lesions escaped
detection by both noninvasive tests. Sources of diagnostic error for both
tests were defined. We believe that the combination of duplex ultrasound
and ocular pneumoplethysmography significantly improves the overall
assessment of carotid atherosclerosis.
