The Accuracy of Ultrasound Examination to Diagnose Thyroid Related Malignancies

Thyroid nodules are a common clinical problem and the incidence of thyroid nodules has increased with the recently increased use of thyroid ultrasonography (US). Several previous studies have demonstrated that thyroid nodules are found in 4-8% of the general population with the use of palpation, in 19-67% of patients with the use of US and in 50% of autopsy specimens . Malignancies have been found in 9-15% of the nodules that were evaluated with fine-needle aspiration (FNA) biopsy . The same as in other countries, the incidence of thyroid cancer is rapidly increasing in Korea and it is becoming the most common cancer in Korean women, followed by breast cancer, according to the recent report.

Thyroid nodules are especially more common in elderly patients, female patients, patients with iodine deficiency and patients with a history of neck irradiation. Uncommonly, a thyroid nodule can cause local compression or hyperthyroidism and so it should be treated accordingly. Yet the clinical importance of thyroid nodules lies in the detection of malignancy, and malignancy comprises approximately 5% of all thyroid nodules irrespective of the size . The risk factors associated with an increased likelihood of a malignancy in thyroid nodules include a previous history of irradiation, a family history of medullary thyroid carcinoma or multiple endocrine neoplasia (MEN) type II, patients who are younger than 20 years or older than 60 years, male patients, rapid growth of a nodule, a nodule with a firm and hard consistency, an inconspicuous margin of the nodule on palpation, the presence of enlarged cervical lymph nodes and the presence of a fixed nodule.

Among the modern imaging modalities, high-resolution US is the most sensitive diagnostic modality for the detection of the thyroid nodules and it is necessary to perform US for the nodules found after palpation . In addition, US can evaluate the size and characteristic of nonpalpable nodules, it can guide FNA for thyroid nodules and it can diagnose lymph node metastasis. Although thyroid US has been regarded as the mainstay for the management of the thyroid nodules, there has been no clear consensus on the US-based management such as follow-up for thyroid US and the selection of a nodule for FNA biopsies, as well as the standardized terminology for thyroid US. There are many different guidelines and recommendations for the management of thyroid nodules detected on US, and these recommendations and guidelines have been described by different organizations.

Ultrasonography (US) is a diagnostic tool that is most often used before the examination with fine needle aspiration biopsy (FNAB) in diseases of thyroid nodules. US overview include hypoechogenicity, microcalcification, irregular boundary, anteroposterior diameter (AP) is greater than the diameter axial, loss of halo, and intranodulary vascularization. When the specific picture is seen in the results of the examination, the biopsy can be performed.

In addition to the diagnosis of thyroid nodules, the US can be used for qualitative assesment of regional lymph nodes, which is useful to consider the deployment of lymph nodes for desection, and to evaluate the biological characteristics of tumors, including thyroid carcinoma prognosis. US can be used to distinguish between the thyroid lymphoma from chronic thyroiditis, and tiroiditis damage triggers, such as thyroiditis with minimal pain signs, and thyrotoxicosis grave. On this review, we described the advantages US to diagnose thyroid glands anomalies based on data from the institution.

The application of US is to detect thyroid nodules and to distinguish between benign and malignant anomalies, particularly papillary carcinoma. US picture (microcalcifications, hypoechoic, irregular edges, halo sign) is a sign of papillary thyroid carcinoma.

The role of ultrasonography (US) in the diagnosis of cancer in thyroid nodules is not well-established. The aim of the present study was to evaluate US performance in predicting cancer in thyroid nodules using a novel approach. Two hundred and eighty-nine patients with thyroid nodular disease were evaluated with clinical, biochemical and cytopathological examinations. Eighty patients with palpable solitary thyroid nodules or multinodular goiters who were to undergo surgery were included, and had a US exam performed by one of us.

The thyroid gland can be evaluated by many support checkups, such as radionuclide imaging, ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). Although each study has its advantages, US is a diagnostic tool that is most often used to detect thyroid disease, especially thyroid nodules. This is because the US does not only detect nodules but also for evaluating the qualitative of the nodules. The development of the use of US resulted in the increase of mass screening on the thyroid and carotid artery, and to detect non-palpable thyroid nodules ≥ 3 mm. Using a combination of US and US-Guided fine-needle aspiration biopsy (FNAB), malignant nodules can be distinguished from benign nodules.

Tan WJ at al  An audit study of the sensitivity and specificity of ultrasound, fine needle aspiration cytology and frozen section in the evaluation of thyroid malignancies in a tertiary institution. A total of 112 patients underwent thyroid surgery in the 3-year study period. Thyroid malignancy constituted 34 (30%) of all patients who underwent thyroid surgery. The most popular diagnostic tools used were ultrasound (81%), FNAC (69%) and frozen section (59%). The sensitivity of ultrasound, FNAC and frozen section were 41.4%, 86.4% and 68.8%, respectively. FNAC was shown to be a superior diagnostic test in detecting malignancy compared to ultrasound. FNAC was able to pick up 53% of thyroid cancers missed by ultrasound. Frozen section was able to pick up 33% of thyroid cancers that were missed by both ultrasound and FNAC.

For the accuracy of the diagnosis of thyroid nodules and early detection during screening US, report along with scoring, or categories using the classification system is rational. Tae et.al. classify thyroid nodules into three categories based on one of four picture: nodules with microcalcifications, irregular edges or mikrolobulated with hypoechogenicity, and a higher form of broadly classified as category 3 (malignant); nodules which indicates the absence of all of the above characteristics are classified as category 2 (benign); and cystic nodules anechogenic classified as category 1 (benign). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) are  87%, 87%, 48%, and 98%, respectively, by comparing their findings with cytology results.