Diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomographyin the follow-up of papillary or follicular thyroid cancer

Positron emission tomography with 18F-fluorodeoxyglucose is a relatively ne w nuclear imaging technique in oncology. We conducted a systematic review t o determine the diagnostic accuracy of 18F-fluorodeoxyglucose positron emis sion tomography in patients suspected of recurrent papillary or follicular thyroid carcinoma. Two reviewers independently selected, extracted, and ass essed data from relevant literature found in computerized databases and by reference tracking. Prospective and retrospective studies with 10 human sub jects, or more, that evaluated the accuracy of ring positron emission tomog raphy, using 18F-fluorodeoxyglucose in follicular and papillary thyroid can cer, were included. Studies on 18F-fluorodeoxyglucose imaging using gamma c ameras, reviews, case reports, editorials, letters, and comments were exclu ded. The methodological quality was assessed by applying the criteria for d iagnostic tests recommended by the Cochrane Methods Group on Screening and Diagnostic Tests. A rating system was used for qualitative analysis consist ing of four levels of evidence (1 = highest level; 4 = lowest level). Fourt een studies met the inclusion criteria. All studies claimed a positive role for positron emission tomography but, at evidence levels 3 or 4, precludin g quantitative analysis. Methodological problems included poor validity of reference tests and a lack of blinding of test performance and interpretati on. The reviewed material was heterogeneous with respect to patient variati on and validation methodology. The most consistent data were found on the a bility of 18F-fluorodeoxyglucose positron emission tomography to provide an anatomical substrate in patients with elevated serum Tg and negative iodin e-131 scans. In conclusion, the results seem to support the potential of 18 F-fluorodeoxyglucose positron emission tomography to identify and localize foci of recurrent cancer in the latter patient subset. However, implementat ion of positron emission tomography in a routine diagnostic algorithm requi res additional evidence.