[Angiographic quantification of stenoses of the internal carotid artery]

The method of measuring cartid stenosis is under discussion since different methods of quantifying carotid stenosis were used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Stenosis Trial (ECST).

Angiograms from 80 patients (105 cases of stenosis of the internal carotid artery), performed in a simultaneous biplanar manner, were retrospectively analyzed using the NASCET, the ECST method and a method based on measurement of the common carotid (CC) artery lumen diameter. Each linear measurement was converted into the ¿squared¿ method (NASCET2, ECST2, CC2). The linear NASCET and ECST measurements of both views (stenosis 1, stenosis 2) were used to calculate the biplanar stenosis according to the formula: stenosis = stenosis 1 + stenosis 2 - stenosis 1 * stenosis 2, and termed ¿local stenosis ECST-bi¿ and ¿distal related stenosis NASCET-bi¿ Furthermore each stenosis was approximated by two neuroradiologists.

Direct visualization proved agreement with measured local stenosis ECST-bi. Squared methods correlated exactly with linear measurements (Spearmancorrelation), thus providing no further data. Biplanar calculation caused considerable change in the order of the stenosis. The different results of the local stenosis ECST-bi and the distal related stenosis NASCET-bi are not contradictory, but complementary.

Direct visualization should be replaced by measurement of the local stenosis ECST-bi. Biplanar calculation seems to give a better estimate of the degree of the stenosis, causing questions since the results of ECST and NASCET cannot be applied.