title: Effectiveness of [(124)I]-PET/CT and [(18)F]-FDG-PET/CT for localizing recurrence in patients with differentiated thyroid carcinoma.
abstract: Although the prognosis of patients with differentiated thyroid carcinoma (DTC) is generally encouraging, a diagnostic dilemma is posed when an increasing level of serum thyroglobulin (Tg) is noted, without detection of a recurrent tumor using conventional imaging tools such as the iodine-131 whole-body scanning (the [(131)I] scan) or neck ultrasonography (US). The objective of the present study was to evaluate the diagnostic value of [(124)I]-PET/CT and [(18)F]-FDG-PET/CT in terms of accurate detection of both iodine- and non-iodine-avid recurrence, compared with that of conventional imaging such as the [(131)I] scan or neck ultrasonography (US). Between July 2009 and June 2010, we prospectively studied 19 DTC patients with elevated thyroglobulin levels but who do not show pathological lesions when conventional imaging modalities are used. All involved patients had undergone total thyroidectomy and radioiodine (RI) treatment, and who had been followed-up for a mean of 13 months (range, 6-21 months) after the last RI session. Combined [(18)F]-FDG-PET/CT and [(124)I]-PET/CT data were evaluated for detecting recurrent DTC lesions in study patients and compared with those of other radiological and/or cytological investigations. Nine of 19 patients (47.4%) showed pathological [(18)F]-FDG (5/19, 26.3%) or [(124)I]-PET (4/19, 21.1%) uptake, and were classed as true-positives. Among such patients, disease management was modified in six (66.7%) and disease was restaged in seven (77.8%). In particular, the use of the described imaging combination optimized planning of surgical resection to deal with locoregional recurrence in 21.1% (4/19) of patients, who were shown to be disease-free during follow-up after surgery. Our results indicate that combination of [(18)F]-FDG-PET/CT and [(124)I]-PET/CT affords a valuable diagnostic method that can be used to make therapeutic decisions in patients with DTC who are tumor-free on conventional imaging studies but who have high Tg levels.
authors.affiliation: Department of Surgery, Eulji Medical College Hospital, Seoul, Korea.
authors.forename: Jandee
authors.initials: J
authors.lastname: Lee
authors.forename: Kuk Young
authors.initials: KY
authors.lastname: Nah
authors.forename: Ra Mi
authors.initials: RM
authors.lastname: Kim
authors.forename: Yeon-Ju
authors.initials: YJ
authors.lastname: Oh
authors.forename: Young-Sil
authors.initials: YS
authors.lastname: An
authors.forename: Joon-Kee
authors.initials: JK
authors.lastname: Yoon
authors.forename: Gwang Il
authors.initials: GI
authors.lastname: An
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Choi
authors.forename: Gi Jeong
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Euy-Young
authors.initials: EY
authors.lastname: Soh
authors.forename: Woong Youn
authors.initials: WY
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000737:chemistry; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009333:Neck / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals / Q000737:chemistry; D012008:Recurrence; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000601:surgery; D013965:Thyroidectomy; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D051598:Whole Body Imaging
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin