Long-Term Follow-Up of Thyroid Incidentalomas Visualized with 18F-Fluorodeoxyglucose Positron Emission Tomography-Impact of Thyroid Scintigraphy in the Diagnostic Work-Up.

Kirsten Korsholm,Åse Krogh Rasmussen,Louise Alslev,Peter Oturai,Michala Reichkendler

doi:10.3390/diagnostics11030557

Kirsten Korsholm, Åse Krogh Rasmussen + Show 3 more

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https://doi.org/10.3390/diagnostics11030557

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Journal: Diagnostics	Publication Date: Mar 19, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Copenhagen University Hospital, Rigshospitalet

Abstract

Our objective was to evaluate the frequency of malignancy in incidental thyroidal uptake on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in a cohort of Danish patients, and furthermore to evaluate the impact of thyroid scinti-graphy in the diagnostic work-up. All whole-body PET/CT reports from 1 January 2010 to 31 December 2013 were retrospectively reviewed and further analyzed if visually increased thyroidal FDG uptake was reported. Patient electronic files were searched for further thyroid evaluation. Of 13,195 18F-FDG-PET/CT scans in 9114 patients, 312 PET/CT reports mentioned incidental thyroid FDG-uptake, and 279 patients were included in the study (3.1%). The thyroid was further investigated in 137 patients (49%), and 75 patients underwent thyroid scintigraphy. A total of 57 patients had a thyroid biopsy and 21 proceeded to surgery. Surgical specimens displayed malignancy in 10 cases, and one thyroid malignancy was found by autopsy. Hence, 11 patients were diagnosed with thyroid malignancies among 279 patients with incidental thyroid 18F-FDG uptake (3.9%). In 34 patients, a biopsy was avoided due to the results of the thyroid scintigraphy. We conclude that patients with thyroid incidentalomas can benefit from further diagnostic work-up including a thyroid scintigraphy.

Highlights

Incidental thyroid nodules (ITN) are defined as nodules originally detected on imaging studies performed in patients with no thyroid-related clinical symptoms, examination findings, nor suspicion of thyroid disease [1]
Population studies in Denmark have shown that 15% of women in the age group 40 to 45 years have multiple nodules >1 cm in their thyroid gland, and that the prevalence increases to 25–30% in women age 60–65 years [2]; in Denmark the incidence of thyroid malignancy is only 360 new cases per year (6.2 cases per 100,000 inhabitants/year)
We find it of interest to investigate the frequency of FDG-avid ITNs in Eastern Denmark, the frequency of malignant lesions, and the thyroid scintigraphy findings in patients with FDGavid lesions in the thyroid

Summary

Introduction

Incidental thyroid nodules (ITN) are defined as nodules originally detected on imaging studies performed in patients with no thyroid-related clinical symptoms, examination findings, nor suspicion of thyroid disease [1]. In the United States, the incidence of thyroid cancer nearly tripled from 1975 to 2009, and despite this change in incidence, the mortality rate from thyroid cancer remained stable [3]. This is partly explained by over-diagnosing and partly by the fact that small thyroid cancers can have an indolent course, and an ideal approach would be only to diagnose those cancers that are likely to be of clinical significance. A large meta-analysis of 16 studies [9] reported that 9 studies demonstrated a significant difference between malignant and benign lesions, while the other 7 found no such difference, indicating that there is no safe cut-off value below which malignancy can be ruled out

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