B-mode imaging and histomorphometric evaluation of carotid atherosclerosis. The quantitative and qualitative evaluation of atherosclerotic lesions by the ultrasonography has presented several problems, above all, the determination of accuracy and reproducibility of this methodology in humans. The present study aims to evaluated the results of B-mode imaging of extracranial carotid arteries in patients selected for surgery as compared with histologic results of the observations of the samples obtained by endarterectomy. Shrinkage effects of the histologic samples were taken into consideration. Several bidimensional images of atherosclerotic lesions, as obtained by ultrasound at different incident angles, were used to establish their maximum thickness. The maximum degree of the vessel stenosis calculated by ultrasound showed a high correlation (Y = 0.47X + 42.4, se = 0.11, r = 0.5, p less than 0.001) compared with the one obtained by histology. The imaging methodology provided however, a mean overestimation of the stenosis of about 7%. Relationships among the amount of calcium (p less than 0.03); necrotic core p less than 0.056); and echogenic types, ie, soft, mixed, and hard; have been suggested by a statistical trend. The results suggested that of the vascular lumen due to advanced atherosclerotic lesions. Qualitative interpretation of atherosclerosis by B-mode imaging, ie, morphologic characteristics, seem, at present, to be of value, but more investigations in depth are needed. 