الفهرس 
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Abstract
A thyroid nodule is defined as a discrete lesion within the thyroid gland that is radiologically and pathologically distinct from the surrounding normal thyroid parenchyma. It constitutes the most common abnormality of the endocrine system. Using ultrasonography in thyroid nodule detection has been raised the nodule prevalence to reach 67%. 7-15% of thyroid nodules are malignant.
The current goal in the nodule evaluation is to determine whether it is benign or malignant. Usually the US is the first choice among the imaging studies during nodule assessment followed by ultrasound guided fine needle aspiration biopsy (FNAB) and mostly the surgery decision or leaving the nodule alone is dependent on the FNAB result. However, FNAB has several limitations including inadequate sampling, operator dependency and false negative cytology rates (10-30%).
Recently, several studies have been performed using high frequency ultrasonography to determine suspicious features of malignant thyroid nodule. Most studies has agreed that these features are: taller than wider nodules, microcalcification, solid texture, central vascularity, hypoechogenicity and irregular margin but with different statistical accuracy. It is well established that no single sonographic feature has adequate diagnostic accuracy in reliably discrimination between malignant nodules from benign ones.
The purpose of this study is to determine the diagnostic value of US in the evaluation of nodule in comparison with final histopathological examination of thyroid surgical specimen.
In our study, a total of fifty patients aged from 20-50 years old with equivocal or suspicious US/FNAB results underwent hemi-thyroidectomy. Malignant nodule (proved by FNAB) underwent total thyroidectomy. We considered the nodule was suspicious for malignancy if it had two or more of suspicious malignant features of US.
The present study results revealed that microcalcification is the best suspicious us thyroid feature that should be relied on during examination followed by taller than wider feature.
The sensitivity of ultrasound in detecting different types of thyroid nodules was 100.0 %, with specificity 94.12 % and accuracy 96.0%. Also, sensitivity of Bethesda system of FNAB in detecting different types of thyroid nodules was 37.50 %, with specificity100.0 % and accuracy 80.0 %. Both of FNAB and US results were statistically significant. But the US had better preference than FNAB in diagnosis of 12 malignant cases.