Malignant carotid artery invasion: sonographic detection

To assess the reliability of sonography in the detection of absence of invasion of the carotid artery by tumor, high-resolution ultrasound, surgical, and pathologic findings were prospectively evaluated in 24 patients with disease metastatic to the neck. Sonography performed with 5- and 10-MHz transducers had a sensitivity of 100% for the demonstration of absence of carotid invasion. Stringent criteria were used to eliminate false-negative studies. There were only five false-positive studies, for a positive predictive rate of 44.4%. Specific criteria for diagnosis of carotid invasion included visualization of an obvious break in the carotid wall with an offset in two planes and sonographic demonstration of gross tumor within the lumen. False-positive interpretations are more likely if there is inability to image the vessel at a perpendicular interface, if the abnormality cannot be seen in two planes, or if the neoplastic mass adjacent to the carotid considerably attenuates the acoustic beam.