Ultrasound of benign thyroid nodules: A 120 months follow-up study

Thyroid Nodules: Past, Present, and Future

BACKGROUND

Over the past millennia, the evaluation and management of thyroid nodules has essentially remained the same with thyroidectomy as the only reliable method to identify malignancy. However, in the last 30 years, technological advances have significantly improved diagnostic management of thyroid nodules. Advances in imaging have allowed development of a reliable risk- based stratification system to identify nodules at increased risk of malignancy. At the same time, sensitive imaging has caused collateral damage to the degree that we are now identifying and treating many small, low risk nodules with little to no clinical relevance.

OBJECTIVE

To review the history of thyroid nodule evaluation with emphasis on recent changes and future pathways.

METHODS

Literature review and discussion.

RESULTS

Thyroid ultrasound remains the best initial method to evaluate the thyroid gland for nodules. Different risk-of-malignancy protocols have been developed and introduced by different societies, reporting methods have been developed and improved each, with goals of improving the ability to recognize nodules requiring further intervention and minimizing excessive monitoring of those who do not. Once identified, cytological evaluation of nodules further enhances malignancy identification with molecular markers assisting in ruling out malignancies in indeterminate nodules preventing unneeded intervention. And all societies have urged avoidance of overdiagnosis and overtreatment of low-risk cancers of little to no clinical relevance.

CONCLUSION

In this review, we describe advancements in nodule evaluation and management, while emphasizing caution in overdiagnosing and overtreating low-risk lesions without clinical importance.

Ultrasound characteristics of follicular and parafollicular thyroid neoplasms: diagnostic performance of artificial neural network

BACKGROUND

Ultrasound is the first-line imaging modality for detection and classification of thyroid nodules. Certain features observable by ultrasound have recently been equated with potential malignancy. This retrospective cohort study was conducted to test the hypothesis that radiomics of the four categorical divisions (medullary [MTC], papillary [PTC], or follicular [FTC] carcinoma and follicular thyroid adenoma [FTA]) demonstrate distinctive sonographic characteristics. Using an artificial neural network model for proof of concept, these sonographic features served as input.

METHODS

A total of 148 patients were enrolled for study, all with confirmed thyroid pathology in one of the four named categories. Preoperative ultrasound profiles were obtained via standardized protocols. The neural network consisted of seven input neurons; three hidden layers with 50, 250, and 100 neurons, respectively; and one output layer.

RESULTS

Radiomics of contour, structure, and calcifications differed significantly according to nodule type (p = 0.025, p = 0.032, and p = 0.0002, respectively). Levels of accuracy shown by artificial neural network analysis in discriminating among categories ranged from 0.59 to 0.98 (95% confidence interval [CI]: 0.57-0.99), with positive and negative predictive ranges of 0.41-0.99 and 0.78-0.97, respectively.

CONCLUSIONS

Our data indicate that some MTCs, PTCs, FTCs, and FTAs have distinctive sonographic characteristics. However, a significant overlap of these characteristics may impede an explicit classification. Further prospective investigations involving larger patient and nodule numbers and multicenter access should be pursued to determine if neural networks of this sort are beneficial, helping to classify neoplasms of the thyroid gland.

Identifying and Predicting Diverse Patterns of Benign Nodule Growth

CONTEXT

The natural history of benign thyroid nodules is typically characterized by slow growth and minimal risk of malignant transformation. Available data have, to date, been unable to elucidate the diversity of benign nodule growth patterns over time nor predictive of which patients follow which pattern.

OBJECTIVE

We aimed to better define the diverse patterns of benign nodule behavior and their predictors.

METHODS

We prospectively studied 389 consecutive patients with solitary, solid, cytologically benign thyroid nodules ≥1 cm and follow-up ultrasound for at least 4 years. Demographic, sonographic, biochemical data were collected at initial evaluation, and subsequent growth patterns were identified over the follow-up. Predictors of growth at initial evaluation and 3 years of follow-up were defined.

RESULTS

The mean (±SD) follow-up was 7.7 (±2.7) years. Three distinct growth patterns were identified: A) stagnant nodules with average growth rate < 0.2 mm/year; B) slow-growing nodules with a rate 0.2 to 1.0 mm/year; and C) fast-growing nodules increasing > 1.0 mm/year. Fast-growing nodules represented 17.2% of the cohort, and were more frequent in patients younger than 50 years (OR 2.2 [1.2-4.1], P = 0.016), and in larger nodules (2.0-2.9 cm, OR 3.5 [1.7-7.1], P = 0.001; >3.0 cm, OR 4.4 [1.8-10.4], P = 0.001 vs reference 1-1.9 cm). In a multiple regression model, nodule growth at 3 years at an average growth rate over 0.2 mm/year over 3 years since initial evaluation was an independent predictor of longer-term fast nodule growth, even after adjusting for age, biological sex, TSH level, and nodule size (P < 0.001).

CONCLUSION

The natural history of benign nodule growth is diverse, with over 80% of nodules demonstrating minimal to no growth long-term. Nearly 20% of cytologically benign nodules may exhibit a fast, continued growth pattern, which can be predicted by the 3-year growth rate pattern. These findings can help inform decision making for tailored benign nodule follow-up and monitoring.

When and why patients drop out from benign thyroid nodules follow-up: a single centre experience

PURPOSE

Drop-out in clinical long-term follow-up is a general problem that is potentially harmful to patients. No data about patients that drop out from thyroid ultrasound follow-up is available literature. The aim of the present retrospective study was to evaluate the characteristics of patients that dropped out from ultrasound thyroid nodule follow-up.

PATIENTS AND METHODS

We reviewed medical records of all consecutive patients who underwent a fine needle aspiration from January 2007 to March 2009 in our department. All the patients with benign nodule(s) were recommended annual ultrasounds; patients who had dropped out from follow-up were included and a telephone interview was obtained to evaluate the reasons for dropping out.

RESULTS

289/966 (30%) of patients with benign nodules dropped out during follow-up; 94% of them within the first 5 years. Phone interviews were obtained from 201/289 (70%) of the patients. In the 57% of cases, the main declared reason for dropping out was nodular dimension stability during the first 2-3 years; 8.7% of them had forgotten about the appointment; 6.4% of subjects claimed to check only serum TSH, and 3.2% stated that they would undergo an ultrasound only if the nodule(s) were symptomatic. Finally, 10.7% patients continued follow-up in other centres.

CONCLUSION

we showed that a third of patients miss their thyroid ultrasound follow-ups, and that the major cause is the low perceived threat coming from the disease. As a certain amount of drop-out is inevitable, attempting to reinforce our patients' awareness regarding their own health state is mandatory.

TRIAL REGISTRATION

Trial registration: no. 4084.