A high-resolution ultrasound B-mode imaging system combined with a 16sequential range-gated pulsed Doppler flow measuring device was used for the evaluation of nonstenotic extracranial carotid artery disease. Various types of atherosclerotic lesions were differentiated by Duplex system examinations in 54 carotid arteries examined in vitro in a postmortem study and in 51 carotid arteries examined in vivo from patients with angiographically proven cerebrovascular disease. In addition, the multigated Doppler system allowed the analysis of flow velocity profiles throughout the carotid arteries, the distinction between intraarterial flow and recent thrombus, and in particular the estimation of local flow alterations, which are diagnostic in the presence of sonolucent and shadowed plaques behind echo-dense lesions. A number of difficulties, which at present limit the application of Duplex system examination as a noninvasive "stand alone" method for detecting carotid disease, are discussed. Indexing Words: Atherosclerosis * Ultrasonic arteriography * Duplex scanning * Doppler profiles Noninvasive ultrasonic methods providing carotid artery flow analysis have proved considerably valuable for the detection of obstructive lesions of the extracranial carotid arteries. '-'
However, these methods either fail to indicate reliably low-grade stenosis, minimal nonstenotic lesions and early irregularities of the arterial wall, or they cannot distinguish correctly flow disturbances secondary to mild disease from physiologically present ones. Furthermore, even if discrete abnormalities of the velocity patterns could be more accurately diagnosed and differentiated from normals, as was recently reported by Roederer et a1. : they still could not provide any information about the size, extent and surface (ulcerated versus smooth plaques) of these lesions, which may be associated with embolic cerebral ischemic events. Thus, the major aim of recently developed ultrasonic imaging techniques and of From the Department of Neurology, Medical School, University of Duesseldorf, West Germany. This study waa supported by the Deuteche Fomhungsgemeinschatl SFB 200/D2. Manuscript