The difficulty of quantifying the severity of carotid stenosis.

The problems of quantifying internal carotid stenoses were studied by analyzing 119 arteriograms. The normal carotid artery diameters, corrected for arteriographic magnification, are reported. Using these measurements, a theoretical comparison is made between the different methods that have been used for defining the severity of a carotid stenosis. Also, in the 119 arteriograms, the minimum residual lumen diameter of the stenosis was compared with the calculated percentage area of stenosis, the percentage diameter of stenosis, and the qualitative estimates of stenosis made by radiologists. Based on these data and other theories, it is concluded that the measurement of the minimum residual lumen diameter is the preferred method for quantifying the severity of carotid stenoses and that its use will avoid some of the current confusion in interpreting the results of noninvasive and clinical studies.