Evaluation of Malignancy Risk in 18F-FDG PET/CT Thyroid Incidentalomas

Abstract

Thyroid incidentalomas detected by 18 fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography/computed tomography (PET/CT) are a real challenge for nuclear medicine physicians and clinicians. This study aimed to evaluate the risk of malignancy for patients with focal thyroid incidentalomas (TIs) diagnosed through FDG PET/CT. Data from 6900 patients, with a known primary tumor, who had an FDG PET/CT investigation performed were analyzed for the presence of incidental thyroid uptake. The focal TIs were reported, and the patients were referred for further investigation to the endocrinology department. There were 126 patients (1.82%) who presented with focal thyroid uptake, and for 87 of them, investigations were completed with ultrasonography (US), and for 29 with a fine needle aspiration biopsy (FNAB) procedure. Malignancy was detected in 7.93% (10/126) of cases. An arbitrary cutoff value of four was established for the standard uptake value lean body mass (SUVlbm Max) to differentiate the malignant nodules from the benign ones, and this value was significantly associated with malignancy (p = 0.0168). TIs are not so frequent, but they have a potential malignancy risk, and a proper evaluation is required. Even though SUVlbm Max is a predictive factor for malignancy, the FNAB remains the main diagnostic method for the therapeutic management of these patients.

Benefits And Harms Of Implementing [18F]FDG-PET/CT For Diagnosing Recurrent Breast Cancer: A Prospective Clinical Study

“…None of the patients (0 of 12) in this cohort were diagnosed with colorectal cancer, but one out of 12 patients (8.3%) with focal [ 18 F]FDG-uptake in the thyroid gland was diagnosed with thyroid cancer. Our ndings are based on small numbers but correspond well with the approximately 8% malignancy rates found in other studies of focal [ 18 F]FDG-uptake in the thyroid gland [19,20]. This study con rms the high diagnostic accuracy of [ 18 F]FDG-PET/CT in examining suspected recurrent breast cancer reported in previous studies [4,21].…”

Focal Thyroid Incidentalomas on 18F-FDG PET/CT: A Systematic Review and Meta-Analysis on Prevalence, Risk of Malignancy and Inconclusive Fine Needle Aspiration

“…In the patient flow domain, 27 studies were classified as high risk because not all included patients received FNAC and/or surgery ( 24 , 26 , 27 , 30 , 31 , 33 , 34 , 37 , 39 , 41 , 45 , 47 , 48 , 50 , 52 , 55 , 56 , 59 , 61 , 63 , 64 , 67 , 70 , 71 , 73 , 81 , 82 ). Another 8 studies were considered to have a high risk of bias because FNACs were performed only after suspicious US ( 25 , 40 , 44 , 51 , 62 , 66 , 72 , 77 ).…”

“…Fifteen studies could be used to investigate the pooled ROIF after initial FNAC. Reasons for exclusion were: (1) missing data of non-diagnostic and indeterminate FNAC results (N = 28) ( 23 – 25 , 27 – 29 , 32 , 33 , 35 – 37 , 39 , 40 , 51 , 53 , 54 , 59 , 60 , 62 , 64 , 65 , 67 , 69 , 74 , 77 , 80 , 81 , 83 ). (2) inconsequent description of data of non-diagnostic or indeterminate FNAC results (N = 5) ( 41 , 45 , 52 , 66 , 73 ).…”

The Evaluation of Malignancy Rate of Incidental Thyroid Nodules Detected by FDG-PET/CT

“…Several previous studies have investigated the highly variable malignancy rates (8-64%) in incidental thyroid nodules detected in FDG-PET/CT scans (8,9). Also, the 2015 American Thyroid Association guideline recommended performing FNAB because of an increased risk of malignancy in thyroid nodules larger than 1 cm detected with FDG-PET/CT and confirmed by USG (1).…”