Real-time B-mode carotid imaging in diagnosis of cerebrovascular disease

We studied 1,044 patients by using real-time B-mode ultrasonic carotid imaging (BioSound), oculoplethysmography and carotid phonoangiography (OPG/CPA), and periorbital Doppler ultrasonography. One hundred and fifty of these patients underwent bilateral carotid arteriography; they form the basis of this study. The x-ray films were compared to the scans and other noninvasive studies. The quality of the B-mode scans were graded according to the severity of disease (the degree of diameter reduction of the arterial lumen by stenosis): grade I (0% to 39% stenosis), grade II (40% to 69% stenosis), and grade III (70% stenosis and greater). The overall results showed that the specificity of the scan was 86%, sensitivity for grade II disease was 75%, and sensitivity for grade III disease was 44%. Only 6 of 16 (38%) totally occluded vessels were identified correctly. The data reveal a direct correlation of scan quality with accuracy. Good-quality scans had 90% accuracy, whereas the accuracy of poor-quality scans was 48%. Four of 12 scan/arteriogram "mismatch" patients underwent carotid endarterectomy. In each instance the surgeon thought that the scan more accurately represented the disease process. When the scan was combined with OPG/CPA and the results agreed, there was a 91% accuracy rate. However, when the scan and OPG/CPA disagreed, the scan was more reliable in the grade I and II categories, whereas the OPG/CPA was much more reliable in grade III disease. The accuracy of this technique can be improved with the addition of a high-quality Doppler system. If technologic improvements can be made so that technically good scans can be obtained in all patients, then this may become the most reliable noninvasive cerebrovascular testing method.