What is the role of ultrasonography in the diagnostic workup of thyroid nodules?

Updated: Jan 09, 2018
  • Author: Steven K Dankle, MD; Chief Editor: George T Griffing, MD  more...
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Answer

Because of advances in technology, ultrasonography is highly sensitive in determining the size and number of thyroid nodules. By itself, ultrasonography cannot reliably be used to distinguish a benign nodule from a malignant nodule. However, combining high-resolution sonography with Doppler and spectral analysis of the vascular characteristics of a thyroid nodule holds promise as a useful tool in screening thyroid nodules for malignancy. Studies have shown that the risk of malignancy is lower in nodules with a predominantly perinodular pattern than in nodules with an exclusively central vascular pattern. Furthermore, if the vascular characteristics of thyroid nodules are combined with their ultrasonographic parameters, including a halo, microcalcifications, cross-sectional diameter, and echogenicity, the predictive value of this imaging approach may increase. [4, 5, 6, 7]

Given the evidence suggesting the increase in thyroid nodule and thyroid cancer diagnosis is largely attributable to advances in high resolution ultrasonography as well as the evidence that such imaging can have predictive value in distinguishing benign disease from malignancy, efforts to standardize thyroid ultrasound reporting have been made.  Su, H et al have published a recent consensus report by a multidisciplinary panel of specialists in which recommendations for standardized thyroid ultrasound reporting have been made.  These recommendations outline characterization of both thyroid nodules and regional lymph nodes in the neck. [8]

Haugen et al developed the 2015 American Thyroid Association guidelines for management of thyroid nodules in which they have stratified the estimated risk of malignancy based on specific ultrasonographic characteristics of thyroid nodules and the recommendations for those nodules which warrant biopsy based on suspicious ultrasound patterns and nodule size. [1]  Tessler et al expanded on these guidelines and proposed a risk-stratification system based on ultrasound thyroid-nodule characteristics (composition, echogenicity, shape, margin, and echogenic foci) to determine which thyroid nodules need biopsy. [9]  

Thyroid ultrasonography can be helpful in certain cases when it is used to guide FNAB. Data have suggested that ultrasonography-guided FNAB may be preferable to palpation-guided FNAB. [10] Although sensitivity and specificity are not clearly and significantly between the approaches to FNAB, many authors consider image-guided FNAB to hold certain advantages. For example, image-guided FNAB may be particularly helpful in the assessment of nonpalpable or small nodules, nodules with cystic components, or nodules that are difficult to access (eg, posterior or substernal nodules). Ultrasonography-guided FNAB, combined with on-site cytologic verification of the adequacy of the specimen by a cytotechnologist or pathologist, may likely provide the highest sensitivity and specificity. Whether this is the most cost-effective approach for all thyroid nodules remains an issue.

In a study of 261 patients undergoing surgical evaluation for thyroid disease, Mazzaglia investigated whether office-based, surgeon-performed ultrasonographic examination significantly affected operative treatment of the patients even though all of these individuals had previously undergone ultrasonographic thyroid examination. Mazzaglia reported that treatment plans for 46 patients (17.6%) were altered because of significant differences between outside and surgeon-administered ultrasonograms. In 12 patients, for example, previously unidentified nonpalpable, enlarged lymph nodes were found in the surgeon-administered ultrasonograms, with biopsy revealing metastatic thyroid cancer in 3 of these patients. Mazzaglia concluded that surgeon-performed ultrasonographic examinations can be used to make necessary changes in surgical treatment and to avoid unnecessary surgery. [11]


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