Duplex scanning of the thyroid.

High resolution ultrasound scanners are used to image nodular thyroid glands and in the study of thyroid malignancy. There are no specific ultrasonic characteristics of malignant lesions to distinguish them from benign conditions. Preliminary results using a Duplex ultrasound scanner shows that the detection of a high frequency Doppler-shift signal from the superior thyroid artery is indicative of an overactive thyroid. In a study of 23 consecutive patients who were being investigated for possible hyperthyroidism, 15 were found to have normal thyroid function and 8 to be overactive. The normals had a mean systolic peak frequency of 1.77 +/- 1.75 kHz, and the hyperthyroid group 4.08 +/- 1.5 kHz. This result is highly significant, having a p value less than 0.0002 (Mann-Whitney U Test). In another 10 patients with solid lesions, one was diagnosed as follicular carcinoma. High frequency Doppler shift signals, similar to those found in carcinoma of the breast, were detected in the periphery of the lesion but were not found in nine cases of adenoma. Duplex scanning may assist in the investigation of hyperthyroidism and in the differential diagnosis of benign and malignant lesions.