ABSTRACT Objective: To conduct a prospective study of the diagnostic value of features of cervical lymph nodes (large size, central location, abnormal shape, cystic changes, cal- cifications, and loss of echogenic hilum), assessed by neck ultrasonography (US), in patients scheduled for surgical treatment of persistent or recurrent differentiated thyroid cancer. Methods: We studied 152 US abnormalities in 42 patients (median age, 38.5 years) who had undergone one or more neck operations, with or without radioiodine ther- apy, but continued to have persistent or recurrent disease, which was confirmed by fine-needle aspiration. Another surgical procedure was planned for these patients. On the day of operation, patients underwent a detailed US neck examination by an experienced radiologist. US abnormal- ities were plotted on a standard diagram of the neck and given specific numbers to help track them during surgical intervention and histopathologic examinations. The US features were compared with the final histopathologic diagnosis. Results: Of 152 US abnormalities, 127 involved cer- vical lymph nodes and 25 involved other types of tissue. In univariate analysis, size, absent echogenic hilum, cystic changes, calcifications, and central location (medial to the sternomastoid muscle) of cervical lymph nodes were sig- nificantly associated with the presence of metastatic involvement. In multivariate analysis, only central loca- tion (odds ratio, 4.07; 95% confidence interval [CI], 1.64 to 10.10) and size (odds ratio, 5.14; 95% CI, 1.64 to 16.06) remained significant. The receiver operating characteristic curve for the size of lymph nodes showed a large area under the curve of 0.77 (95% CI, 0.68 to 0.85), and a size of 7.5 mm showed the highest sensitivity and specificity. Conclusion: Size and central location of cervical lymph nodes assessed by US during follow-up of patients with differentiated thyroid cancer were the most important predictors of presence of metastatic disease. (Endocr Pract. 2005;11:165-171) INTRODUCTION The standard approach to the management of differ- entiated thyroid cancer (DTC) is total or near-total thy- roidectomy followed by radioiodine (RAI) ablation of remnant thyroid tissue and long-term thyroid hormone suppression (1-3). Long-term surveillance for recurrence is achieved mainly by clinical assessment, measurement of serum thyroglobulin, and RAI whole-body scanning (1,2,4). With the adoption of these strategies in the initial management and subsequent follow-up of DTC, the out- come has improved substantially—about 80 to 90% of patients enjoy long-term disease-free survival (5-8). Despite this excellent outcome in the majority of cases of DTC, about 20 to 40% of patients continue to have evi- dence of persistent disease or many years later have recur- rent cancer after an apparent initial cure (5-8). Most of these patients have neck disease, primarily involving the cervical lymph nodes (5-7). In most of these cases, the serum thyroglobulin level remains detectable or elevated, whereas RAI whole-body scanning frequently shows no abnormal findings (9-12). High-resolution neck ultra- sonography (US) has emerged as a highly sensitive imag- ing procedure for detection of cervical lymph nodes and other abnormalities in the neck area (13-18). When the presence of persistent or recurrent disease is suspected, fine-needle aspiration (FNA) guided by US is usually per- formed (13,19). US not only guides the operator to the sites of abnormal findings but may improve the diagnostic yield by directing FNA to the most suspicious lesions. DIAGNOSTIC ACCURACY OF HIGH-RESOLUTION NECK ULTRASONOGRAPHY IN THE FOLLOW-UP OF DIFFERENTIATED THYROID CANCER: A PROSPECTIVE STUDY Ali S. Alzahrani, MD, FACE, FACP, 1 Hamad Alsuhaibani, MD, 2 Suzan Abdel Salam, MD, 1 Saud N. Al Sifri, MD, 1 Gamal Mohamed, PhD, 3 Saif Al Sobhi, MD, 4 Othman Sulaiman, MD, 1 and Mohamed Akhtar, MD 5 Submitted for publication March 9, 2005 Accepted for publication April 4, 2005 From the Departments of 1 Medicine, 2 Radiology, 3 Epidemiology, Biostatistics, and Scientific Computing, 4 Surgery, and 5 Pathology, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. Address correspondence and reprint requests to Dr. Ali S. Alzahrani, Department of Medicine (MBC-46), King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh 11211, Saudi Arabia. © 2005 AACE. ENDOCRINE PRACTICE Vol 11 No. 3 May/June 2005 165 Original Article Abbreviations: AJCC = American Joint Committee on Cancer; DTC = differentiated thyroid cancer; FNA = fine-needle aspi- ration; RAI = radioiodine; ROC = receiver operating characteristic; US = ultrasonography