BACKGROUND
Thyroid ultrasound is the best study when a physician feels an abnormality on the patient’s neck, the patient has a compressive neck symptoms like trouble swallowing, or to monitor a previously diagnosed thyroid nodule. The information generated by a thyroid ultrasound is used to determine whether any additional therapy is needed. However, it is not a good test for screening of thyroid abnormalities, as this can result in diagnosing too many small thyroid cancers that would otherwise not affect a patient’s lifespan. Another big portion of small thyroid nodules are detected on other types of imaging tests that are done for other reasons, such as chect CT scans to evaluate problems in the lungs. In addition, some ultrasounds are also ordered due to vague complaints of fatigue, which contribute to the rise in the number of ultrasounds performed in the United States.

This study was done to determine reasons for obtaining a thyroid ultrasound and determine under what circumstances nodules detected made a clinically significant difference in the patient’s life. With this study, physicians and patients might have a better understanding of appropriate use of the ultrasound machine.

THE FULL ARTICLE TITLE
Kennedy E et al. Rates of detecting thyroid nodules recommended for biopsy with ultrasound: are all indications equal? Thyroid 2023;33(12):1434-1440; doi: 10.1089/thy.2023.0234. PMID: 37981778.

SUMMARY OF THE STUDY
All adult patients who received a thyroid ultrasound at a United States academic medical center from 2017 to 2019 were studied, totaling 1739 patients. Of the patients, 86% were white, 76% were female, and 62% had private insurance. Patients with previous ultrasounds, no indication for the ultrasounds, or the ultrasounds performed to evaluate another anatomic structure than the thyroid gland were not included.

The most common indication for the ultrasound was a suspected nodule on physical exam at 40%, and the next common indication was to further characterize a nodule previously diagnosed with another imaging test (28%). Of all the ultrasounds, only 62% of the ultrasounds performed showed a thyroid nodule, and only 27% of the nodules met criteria for further evaluation with a thyroid biopsy. When only considering the ultrasounds done to follow up a nodule diagnosed on another imaging test, the percentages of nodules and biopsies required increased to 94% and 55%, respectively. The percentage of nodules on the ultrasounds of patients whose physician felt a neck abnormality was 55%, and percentage of nodule on ultrasounds for patient with metabolic symptoms was 43%. Only 39% of the ultrasounds performed for compressive symptoms of patients showed nodules. Not only did this group have the smallest size of nodules (1.2 cm), but also the lowest portion of those nodules got biopsied (6%).

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Non-ultrasound imaging tests resulted in the highest percentage of nodules found on subsequent ultrasounds and the highest rate of biopsies performed on these nodules. Other indications for ultrasound (nodules felt by physicians on exam, compressive symptoms felt by the patient, or metabolic symptoms) only revealed nodules at the same rate as the baseline population. While detection of thyroid cancer has increased, the death rates have remained the same. It is still appropriate to use ultrasound for nodules detected on other imaging tests and for a suspected nodule palpated by the physician based on physical exam, but it might not be appropriate to perform ultrasound based on nonspecific patient symptoms given high costs associated with monitoring or intervening on thyroid nodules or cancer.

— Pinar Smith, MD

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