Purpose: Establish the value of sonographic criteria in detecting invasion of carotid artery by malignant neoplasms.
Methods and materials: During a 3-year period, we examined 32 patients (27 men and four women, aged 21-71 years) with proved head and neck cancer: squamous cell carcinoma in 29, paraganglioma in one case and salivary gland carcinoma in one. All patients were clinically suspected of invasion; with computed tomography scanning inconclusive. Six patients had received radiation therapy previously. Sonography was performed with a 7-11 MHz transducer. The criteria for carotid invasion were loss of hyperechoic interface of the carotid wall; tumor fixation (mobility was used to exclude infiltration by dynamic maneuvers such as sonopalpation or swallowing); encasement (contact area between tumor and vessel more than 180 degrees) and narrowing and deformity of the lumen.
Results: Twenty patients underwent surgery, with pathologic correlation. Fourteen examinations were true-negative, 3 were true-positive, none was falsely negative and 3 were falsely positive. Sensitivity was 100%. Specificity was 82.4%. Positive predictive value was 50%. Negative predictive value was 100%. Accuracy was 85%.
Conclusion: High resolution ultrasound showed a good accuracy in detecting malignant invasion of the carotid artery. Loss of hyperechoic interface of the carotid wall, tumor fixation in the vessel wall, and narrowing and deformity of the lumen were the best criteria when used together. All falsely positive studies were associated with loss of hyperechoic interface of the carotid wall, when used as a single criterion. Dynamic maneuvers were very helpful to exclude infiltration.