Risk of malignancy in thyroid incidentalomas identified by fluorodeoxyglucose-positron emission tomography

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Thyroid tumors frequently display heightened metabolic activity and increased glucose uptake, detectable by fluorodeoxyglucose-positron emission tomography (FDG-PET).
• The occurrence of newly identified thyroid lesions during routine FDG-PET scans has not been previously documented.

Purpose of the Study:

• To determine the incidence of new thyroid lesions, termed incidentalomas, discovered during routine fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.
• To evaluate the characteristics and outcomes of these thyroid incidentalomas.

Main Methods:

• A retrospective analysis was conducted on patients who underwent FDG-PET imaging between June 1996 and March 2001.
• Thyroid incidentaloma was defined as a lesion identified on FDG-PET in patients without prior thyroid disease history. Follow-up data were collected.

Main Results:

• Thyroid incidentalomas were identified in 2.3% of 4525 FDG-PET examinations.
• Of 15 patients with thyroid biopsies, 47% were diagnosed with thyroid cancer, 40% with nodular hyperplasia, and others with thyroiditis or indeterminate cells.
• Malignant lesions exhibited higher standardized uptake values (SUVs) compared to benign lesions.

Conclusions:

• The incidence of thyroid incidentalomas detected by FDG-PET is 2.3%.
• A significant proportion (47%) of biopsied incidentalomas were malignant, underscoring the need for tissue diagnosis.
• Standardized uptake values may assist in differentiating between benign and malignant thyroid lesions found on FDG-PET.