Role of high frequency ultrasound in evaluation of solitary thyroid nodule and comparison with fine needle aspiration cytology

Authors:Paarthipan N, Chandrika Gurulingappa Teli, Nilesh N. Kate, Jaiganesh S, Venkateswaran A, Manu Srinivas
Int J Biol Med Res. 2012; 3(3): 2158-2162  |  PDF File

Abstract

Objective : To determine the diagnostic accuracy & efficacy of high frequency ultrasound in differentiating benign from malignant solitary thyroid nodules and compare the results with FNAC Methods: In 300 patients with suspected solitary thyroid nodule referred from the Departments of Otorhinolaryngology, Medicine, Surgery, Endocrinology, ultrasound was performed in the Department of Radiology & Imaging Sciences. Ultrasonogram of thyroid was done on ALOKA-SSD 1700 scanner with a 7.5/mHz flat probe, with the patient in the supine position with the neck extended. Fine needle aspiration of the thyroid nodule was performed in 292 of these patients in the Dept. of Endocrinology and the smears sent for cytology. Ultrasound diagnosis was compared with the fine needle aspiration cytology report. Results:-Thyroid nodules were found predominantly in females (Ratio 4:1) both in benign as well as in malignant lesions. The most common presenting symptom was a painless swelling in the neck followed by hoarseness of voice. The age group commonly affected was 3rd to 4th decade. On US examination, additional nodules were detected in 72 patients Benign lesions accounted for 74% of the patients and malignant lesions for 26%. The benign lesions in descending order of occurrence were Colloid nodules (46%) Cystic lesions (14.4%) Adenomas (5%) Thyroiditis (5%) Abscess (1.5%). The most common benign lesion was nodule with cystic degeneration. The diagnostic accuracy in the evaluation of colloid nodules on USG is 100%. Nodules with well defined margins and which were predominantly hyper echoic with cystic contents were more likely to be benign. The presence of a peripheral halo, coarse calcification and peripheral blood flow pattern also favored benignancy. Malignant lesions in descending order of occurrence were Papillary carcinoma (17.3%) follicular carcinoma (7.2%), and Anaplastic carcinoma (2%). Nodules with ill defined margins and which were predominantly hypo echoic, with solid internal contents and those with microcalcification and internal blood flow pattern were more likely to be malignant. The diagnostic accuracy of cystic thyroid lesion was 100%. 16 cases of solid hypoechoic nodules with no flow pattern represented Hashimoto’s Thyroiditis. Thus on comparison US with FNAC, few nodules which were diagnosed as benign turned out to be malignant. But none of the lesions predicted as malignant turned out to be benign. Conclusion: High frequency ultrasound has a sensitivity and specificity of 72% and 100% respectively for predicting benign and malignant lesions. US showed sensitivity of 75% for papillary carcinomas and 60% for follicular carcinomas. The overall diagnostic accuracy of high frequency ultrasound in the evaluation of solitary nodule was 85%.