Review. 18F-FDG PET in the diagnosis and follow-up of thyroid malignancy.
The diagnosis of carcinoma of the thyroid is usually made in the process of investigating a thyroid nodule with clinical examination, Technetium-99m scan, ultrasonography and fine-needle aspiration (FNA) cytology. The follow-up is mainly based on 123-iodine and 131-iodine scans and serum thyroglogulin measurement. The aim of the present review was to establish the role of 18F-FDG PET in the differential diagnosis of doubtful thyroid nodules and in the follow-up of patients with increased serum thyroglobulin levels and negative iodine-scan. It remains to be defined if metabolic imaging with PET could be a useful routine procedure in the management of thyroid tumours since the majority of them are well-differentiated and therefore have less avidity to 18F-FDG. In the present work we collected the specific literature derived from MEDLINE over the last 10 years to clarify the potential clinical value of 18F-FDG PET in thyroid malignancies. An emerging role for 18F-FDG PET is in the assessment of incidental finding of a thyroid nodule which, when showing high FDG uptake should be regarded as a possible malignancy that needs further assessment. Another well-documented role for 18F-FDG PET is in the investigation of cases of established well-differentiated thyroid carcinomas presenting with high thyroglobulin and negative iodine imaging. An increase of the 18F-FDG uptake in these tumours indicates a shift towards lesser differentiation (with more aggression and poor prognosis) and may benefit from alternative management. 18F-FDG PET can be considered a routine functional imaging method in detecting iodine-negative recurrent disease in thyroid cancer patients with elevated serum thyroglobulin levels during follow-up. 18F-FDG PET seems to be useful also in differential diagnosis of suspected thyroid nodules, especially using the semi-quantitative SUV analysis.
Al-Nahhas
A
A
Department of Nuclear Medicine, Hammersmith Hospital, London, UK.
Khan
S
S
Gogbashian
A
A
Banti
E
E
Rampin
L
L
Rubello
D
D
D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin