open access

Vol 14, No 2 (2011)
Original articles
Published online: 2012-01-04
Submitted: 2012-01-23
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Incidental 18F-FDG uptake in the thyroid in patients diagnosed with PET/CT for other malignancies

Rafał Czepczyński, Adam Stangierski, Robert Oleksa, Małgorzata Janicka-Jedyńska, Agata Czarnywojtek, Marek Ruchała, Jerzy Sowiński
Nucl. Med. Rev 2011;14(2):68-72.

open access

Vol 14, No 2 (2011)
Original articles
Published online: 2012-01-04
Submitted: 2012-01-23

Abstract

BACKGROUND: The value of PET/CT imaging in diagnosis of different cancers has been widely described. PET/CT may contribute to visualization of additional findings that were not the indication to the study and did not refer to initial diagnosis. In a small number of PET/CT scans an incidentally found focal 18F-FDG uptake in the thyroid gland is found. The goal of the study was to estimate the prevalence and evaluate the clinical significance of incidental thyroid 18F-FDG uptake in a cohort of patients diagnosed for different malignancies.
MATERIAL AND METHODS: 2478 PET/CT scans using 18F-FDG were performed in 1925 subjects for evaluation of different, non-thyroid malignancies. For PET/CT examination, a Discovery ST (General Electric) PET/CT scanner was used. Patients with focal 18F-FDG activity were further evaluated by means of fine needle aspiration biopsy (FNAB). If cytological examination disclosed malignancy or suspicion of malignancy, thyroidectomy was performed. Both cytological and histopathological results were then analyzed.
RESULTS: Focal increased 18F-FDG uptake was found in 71 patients (3.7%), and cytological or histopathological results were evaluable in 20 of them. In general, 8 cases of thyroid cancer were found, which accounts for 40% probability of malignancy. The predominant histopathological diagnosis was papillary thyroid carcinoma (5 out of 8 cases). Additionally, in one case (5%) thyroid metastasis of lung cancer was detected. Diffused 18F-FDG activity in both thyroid lobes was observed in 120 subjects (6.2%) — in most cases chronic thyroiditis was confirmed.
CONCLUSIONS: The probability of malignancy of focal thyroid incidentalomas in 18F-FDG PET/CT scans is rather high. Therefore, thorough evaluation of such lesions is highly recommended in each case. Most thyroid malignancies incidentally detected in PET/CT are papillary carcinomas.
Nuclear Med Rev 2011; 14, 2: 68–72

Abstract

BACKGROUND: The value of PET/CT imaging in diagnosis of different cancers has been widely described. PET/CT may contribute to visualization of additional findings that were not the indication to the study and did not refer to initial diagnosis. In a small number of PET/CT scans an incidentally found focal 18F-FDG uptake in the thyroid gland is found. The goal of the study was to estimate the prevalence and evaluate the clinical significance of incidental thyroid 18F-FDG uptake in a cohort of patients diagnosed for different malignancies.
MATERIAL AND METHODS: 2478 PET/CT scans using 18F-FDG were performed in 1925 subjects for evaluation of different, non-thyroid malignancies. For PET/CT examination, a Discovery ST (General Electric) PET/CT scanner was used. Patients with focal 18F-FDG activity were further evaluated by means of fine needle aspiration biopsy (FNAB). If cytological examination disclosed malignancy or suspicion of malignancy, thyroidectomy was performed. Both cytological and histopathological results were then analyzed.
RESULTS: Focal increased 18F-FDG uptake was found in 71 patients (3.7%), and cytological or histopathological results were evaluable in 20 of them. In general, 8 cases of thyroid cancer were found, which accounts for 40% probability of malignancy. The predominant histopathological diagnosis was papillary thyroid carcinoma (5 out of 8 cases). Additionally, in one case (5%) thyroid metastasis of lung cancer was detected. Diffused 18F-FDG activity in both thyroid lobes was observed in 120 subjects (6.2%) — in most cases chronic thyroiditis was confirmed.
CONCLUSIONS: The probability of malignancy of focal thyroid incidentalomas in 18F-FDG PET/CT scans is rather high. Therefore, thorough evaluation of such lesions is highly recommended in each case. Most thyroid malignancies incidentally detected in PET/CT are papillary carcinomas.
Nuclear Med Rev 2011; 14, 2: 68–72
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Keywords

thyroid nodule; PET; 18F-fluorine-deoxyglucose; thyroid carcinoma

About this article
Title

Incidental 18F-FDG uptake in the thyroid in patients diagnosed with PET/CT for other malignancies

Journal

Nuclear Medicine Review

Issue

Vol 14, No 2 (2011)

Pages

68-72

Published online

2012-01-04

Bibliographic record

Nucl. Med. Rev 2011;14(2):68-72.

Keywords

thyroid nodule
PET
18F-fluorine-deoxyglucose
thyroid carcinoma

Authors

Rafał Czepczyński
Adam Stangierski
Robert Oleksa
Małgorzata Janicka-Jedyńska
Agata Czarnywojtek
Marek Ruchała
Jerzy Sowiński

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