Clinical significance of thyroid uptake on F18-fluorodeoxyglucose positron emission tomography

Abstract

Significant uptake of the thyroid is often identified as an incidental finding on whole-body F18-fluorodeoxyglucose positron emission tomography (FDG-PET) for non-thyroid disease. Sometimes, it is a dilemma for radiologists to interpret clinical significance of thyroid uptake and give adequate recommendation for further evaluation. In general, diffuse uptake of the thyroid glands on FDG-PET is considered to be benign and very likely secondary to thyroiditis and/or hypothyroidism; a further correlation or investigation of the thyroid function and/or ultrasound is helpful. Focal uptake of the thyroid on FDG-PET is defined as an incidentaloma, which is more clinically significant owing to its high risk of malignancy ranging 25-50%. Although maximum standardized uptake value and corresponding computed tomographic finding may help to differentiate benign from malignant lesion, a cytological diagnosis is often advised. The clinical significance of diffuse plus focal uptake of the thyroid on FDG-PET is not well known; it may also be associated with an increased risk of malignancy when compared with a diffuse uptake pattern only.

Integrin αvβ3 Imaging of Radioactive Iodine–Refractory Thyroid Cancer Using 99mTc-3PRGD2

“…Both malignant thyroid tumors and some benign thyroid diseases, such as Graves disease and hyperactive thyroid adenoma, can take up 18 F-FDG. Moreover, cervical lymph nodes with inflammation or other inflamed tissues could show high 18 F-FDG uptake on the PET scans (22). At present in China, SPECT is more widely available than PET.…”

The Rate and Clinical Significance of Incidental Thyroid Uptake as Detected by Gallium-68 DOTATATE Positron Emission Tomography/Computed Tomography

“…Thyroid cancer is one clinically important diagnosis to exclude in a patient found to have a thyroid incidentaloma. There have been studies evaluating the risk of malignancy and the recommended work-up and follow-up for thyroid nodules detected by 18 F-FDG PET scans (3). The normal 18 F-FDG biodistribution does not include the thyroid gland.…”

“…Several Ga-68 DOTA peptides (DOTA-TATE, DOTATOC, DOTANOC) have been used, with DOTATATE found to be the most accurate (5). While there is some published research on Ga-68 DOTATATE PET/ computed tomography (CT) scanning in patients with medullary thyroid cancer and differentiated thyroid cancer to 1 Endocrine Oncology Branch, National Cancer Institute; 3 Diabetes, Obesity, and Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases; 2 PET Department, Clinical Center; National Institutes of Health, Bethesda, Maryland. 4 Thoracic and Endocrine Surgery, University Hospitals of Geneva, Geneva, Switzerland.…”

Incidental Diffuse Thyroid 18F-FDG Uptake Related to Autoimmune Thyroiditis May Be a Favorable Prognostic Factor in Advanced Breast Cancer

“…Patients with breast cancer have a relatively high prevalence of this condition (7), probably because they have a high prevalence of thyroid disorders (8,9). The incidental finding of diffusely increased uptake in the thyroid gland is primarily associated with chronic autoimmune thyroiditis, with or without the presence of hypothyroidism (10,11).…”