Diagnostics of extra-cranial carotid stenoses. Comparison of CW-Doppler sonography and intravenous digital subtraction angiography.

In 98 internal carotid arteries, continuous-wave ultrasound Doppler sonography (USD) and i.v. digital subtraction angiography (DSA) of the internal carotid arteries were performed. The findings were compared with each other prospectively and on the basis of conventional angiography findings. The aim of this investigation was to clarify, whether DSA would show stenoses with lumen restriction of less than 50% more precisely than USD, or whether it would enable clearer localization of any vascular lesions. The results revealed that in cases of haemodynamic effective stenoses and occlusions both procedures correlated well with each other and also with catheter angiography. However, USD and DSA showed increasing discrepancies of findings with decreasing degree of severity of the stenosis. The accuracy for localization of stenoses also decreased markedly for both methods with increasing distance from the carotid bifurcation. In the case of congruent findings of USD and DSA in haemodynamic effective stenoses (degree of stenosis more than 75%) or occlusions conventional angiography did not increase the diagnostic information, and it seems therefore dispensable for vascular surgical decisions. However, in cases with existing clinical symptoms with contradictory or negative USD and DSA findings angiography is still indicated.