The significance of incidental thyroid abnormalities identified during carotid duplex ultrasonography

Hypothesis: Incidental thyroid masses identified during carotid duplex ultrasonography may represent clinically significant lesions. Design and Setting: Retrospective review of a prospective database in a tertiary care referral center. Patients: A total of 2004 consecutive patients from January, 2000, through January, 2002, undergoing carotid duplex ultrasonography. Interventions: After bilateral carotid duplex ultrasonography, selected patients additionally underwent 1 or more of the following: dedicated thyroid ultrasound, fineneedle aspiration biopsy, and/or partial or total thyroidectomy. Main Outcome Measures: The prevalence and type of thyroid abnormalities, correlation with a dedicated thyroid ultrasound, and results of histopathologic diagnosis. Results: One or more thyroid abnormalities were identified in 188 duplexes (9.4%) involving 168 patients. Abnormalities were unilateral in 84 patients (50.6%) and bilateral in 81 patients (49.4%). Seventy-seven abnormalities (47%) were cystic, 72 (43%) were solid, and 16 (10%) were of mixed consistency. Sixty-six of the patients (40%) went on to have formal thyroid ultrasounds. Forty-five patients (70.3%) had masses greater than 1 cm on ultrasound. Based on ultrasound findings, 29 of 66 (44%) underwent fine-needle aspiration biopsy, with 13 of 66 (19.7%) eventually undergoing surgery. Surgical pathology included 5 patients with cancer (3 with papillary cancer, 2 with follicular cancer), 4 patients with a follicular adenoma, and 2 with lymphocytic thyroiditis). Two additional patients were discovered to have parathyroid adenomas following further workup and surgery. Thyroid abnormalities identified during carotid duplex ultrasonography correlated with formal ultrasound in 64 of 66 (97%) patients. Measurement of the thyroid mass by carotid duplex strongly correlated with measurement by formal thyroid ultrasound (r=0.95, P<.001). Two patients with unilateral masses noted on carotid duplex had a normal thyroid formal ultrasound. Conclusions: Incidental thyroid abnormalities identified during carotid duplex ultrasound are common and contain clinically significant pathology. A multidisciplinary clinical pathway may facilitate the appropriate evaluation of these abnormalities.