<abstract xmlns="http://www.w3.org/1999/xhtml"> Background. Incidental 18F-FDG uptake in the thyroid on PET-CT examinations represents a diagnostic challenge. The maximal standardized uptake value (SUVmax) is one possible parameter that can help in distinguishing between benign and malignant thyroid PET lesions. Patients and methods. We retrospectively evaluated 18F-FDG PET-CT examinations of 5,911 patients performed at two different medical centres from 2010 to 2011. If pathologically increased activity was accidentally detected in the thyroid, the SUVmax of the thyroid lesion was calculated. Patients with incidental 18F-FDG uptake in the thyroid were instructed to visit a thyroidologist, who performed further investigation including fine needle aspiration cytology (FNAC) if needed. Lesions deemed suspicious after FNAC were referred for surgery. Results. Incidental 18F-FDG uptake in the thyroid was found in 3.89% ― in 230 out of 5,911 patients investigated on PET-CT. Malignant thyroid lesions (represented with focal thyroid uptake) were detected in 10 of 66 patients (in 15.2%). In the first medical centre the SUVmax of 36 benign lesions was 5.6 ± 2.8 compared to 15.8 ± 9.2 of 5 malignant lesions (p &lt; 0.001). In the second centre the SUVmax of 20 benign lesions was 3.7 ± 2.2 compared to 5.1 ± 2.3 of 5 malignant lesions (p = 0.217). All 29 further investigated diffuse thyroid lesions were benign. Conclusions. Incidental 18F-FDG uptake in the thyroid was found in 3.89% of patients who had a PET-CT examination. Only focal thyroid uptake represented a malignant lesion in our study ― in 15.2% of all focal thyroid lesions. SUVmax should only serve as one of several parameters that alert the clinician on the possibility of thyroid malignancy.</abstract>

Background. Incidental 18F-FDG uptake in the thyroid on PET-CT examinations represents a diagnostic challenge. The maximal standardized uptake value (SUVmax) is one possible parameter that can help in distinguishing between benign and malignant thyroid PET lesions. Patients and methods. We retrospectively evaluated 18F-FDG PET-CT examinations of 5,911 patients performed at two different medical centres from 2010 to 2011. If pathologically increased activity was accidentally detected in the thyroid, the SUVmax of the thyroid lesion was calculated. Patients with incidental 18F-FDG uptake in the thyroid were instructed to visit a thyroidologist, who performed further investigation including fine needle aspiration cytology (FNAC) if needed. Lesions deemed suspicious after FNAC were referred for surgery. Results. Incidental 18F-FDG uptake in the thyroid was found in 3.89% ― in 230 out of 5,911 patients investigated on PET-CT. Malignant thyroid lesions (represented with focal thyroid uptake) were detected in 10 of 66 patients (in 15.2%). In the first medical centre the SUVmax of 36 benign lesions was 5.6 ± 2.8 compared to 15.8 ± 9.2 of 5 malignant lesions (p < 0.001). In the second centre the SUVmax of 20 benign lesions was 3.7 ± 2.2 compared to 5.1 ± 2.3 of 5 malignant lesions (p = 0.217). All 29 further investigated diffuse thyroid lesions were benign. Conclusions. Incidental 18F-FDG uptake in the thyroid was found in 3.89% of patients who had a PET-CT examination. Only focal thyroid uptake represented a malignant lesion in our study ― in 15.2% of all focal thyroid lesions. SUVmax should only serve as one of several parameters that alert the clinician on the possibility of thyroid malignancy.

Thyroid lesions incidentally detected by 18F-FDG PET-CT ― a two centre retrospective study

Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia

Department for Nuclear Medicine, University Medical Centre Ljubljana, Ljubljana, Slovenia

Radiology and Oncology

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Thyroid lesions incidentally detected by F-FDG PET-CT ― a two centre retrospective study

Background. Incidental 18F-FDG uptake in the thyroid on PET-CT examinations represents a diagnostic challenge. The maximal standardized uptake value (SUVmax)...

Thyroid lesions incidentally detected by ¹⁸F-FDG PET-CT ― a two centre retrospective study

Published Online: Mar 25, 2015

Page range: 121 - 127

Received: Jun 29, 2014

Accepted: Sep 22, 2014

DOI: https://doi.org/10.2478/raon-2014-0039

Keywords
thyroid, 18F-FDG, PET-CT, PET incidentaloma, thyroid cancer

© by Marko Grmek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Thyroid lesions incidentally detected by 18F-FDG PET-CT ― a two centre retrospective study

Published Online: Mar 25, 2015

Page range: 121 - 127

Received: Jun 29, 2014

Accepted: Sep 22, 2014

DOI: https://doi.org/10.2478/raon-2014-0039

Keywordsthyroid, 18F-FDG, PET-CT, PET incidentaloma, thyroid cancer

© by Marko Grmek

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Thyroid lesions incidentally detected by ¹⁸F-FDG PET-CT ― a two centre retrospective study

Keywords
thyroid, 18F-FDG, PET-CT, PET incidentaloma, thyroid cancer