title: Value of 111In-DOTA-lanreotide and 111In-DOTA-DPhe1-Tyr3-octreotide in differentiated thyroid cancer: results of in vitro binding studies and in vivo comparison with 18F-FDG PET.
abstract: OBJECTIVE
  Radioiodine-negative thyroid cancer presents diagnostic and therapeutic difficulties, warranting the implementation of new imaging and treatment strategies. The purpose of this study was twofold. First, we investigated in vitro the binding characteristics of 111In-DOTA-lanreotide (111In-DOTA-LAN) and 111In-DOTA-D: Phe1-Tyr3-octreotide (111In-DOTA-TOC) to cells derived from differentiated thyroid cancer (DTC). Second, we evaluated the value of somatostatin receptor (SSTR) scintigraphy with these radioligands, as compared with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), for the detection of tumour lesions in DTC patients.
  
  
  METHODS
  Binding of 111In-DOTA-LAN and 111In-DOTA-TOC to cells isolated from surgically removed thyroid tissue was evaluated in vitro by performing saturation and displacement studies. Eighteen DTC patients with elevated thyroglobulin (12 radioiodine-negative, six radioiodine-positive) were investigated with 111In-DOTA-LAN, 111In-DOTA-TOC and 18F-FDG PET scans.
  
  
  RESULTS
  Large numbers of SSTR binding sites for 111In-DOTA-LAN and 111In-DOTA-TOC were found on the cells investigated. Both SSTR radioligands exhibited a high binding affinity for these SSTR binding sites. 111In-DOTA-LAN and 111In-DOTA-TOC scintigraphy detected 37 and 33 lesions, respectively, in 17 (94%) patients each, whereas 18F-FDG PET revealed 30 lesions in 15 (83%) patients. Uptake of both SSTR radioligands was found in several radioiodine-negative sites. No striking differences in lesion imaging by 111In-DOTA-LAN and 111In-DOTA-TOC were found. In both radioiodine-negative and radioiodine-positive patients, more lesions were SSTR-positive/18F-FDG-negative than were 18F-FDG-positive/SSTR-negative.
  
  
  CONCLUSIONS
  Adding a SSTR scan with these radioligands to the diagnostic work-up increases the diagnostic capacity in DTC, and should be considered particularly in radioiodine-negative patients with elevated thyroglobulin levels.
authors.affiliation: Institute of Nuclear Medicine, Lainz Hospital, Vienna, Austria.
authors.forename: Margarida
authors.initials: M
authors.lastname: Rodrigues
authors.forename: Tatjana
authors.initials: T
authors.lastname: Traub-Weidinger
authors.forename: Maria
authors.initials: M
authors.lastname: Leimer
authors.forename: Shuren
authors.initials: S
authors.lastname: Li
authors.forename: Fritz
authors.initials: F
authors.lastname: Andreae
authors.forename: Peter
authors.initials: P
authors.lastname: Angelberger
authors.forename: Robert
authors.initials: R
authors.lastname: Dudczak
authors.forename: Irene
authors.initials: I
authors.lastname: Virgolini
mesh_terms: D000328:Adult; D000368:Aged; D045744:Cell Line, Tumor; D005260:Female; D019788:Fluorodeoxyglucose F18; D006571:Heterocyclic Compounds / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D010456:Peptides, Cyclic / Q000493:pharmacokinetics*; D049268:Positron-Emission Tomography / Q000379:methods; D011485:Protein Binding; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000378:metabolism*
chemical_list: C507387:111In-DOTA-TOC; D006571:Heterocyclic Compounds; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; C116409:indium 111-DOTA-lanreotide; D019788:Fluorodeoxyglucose F18; D015282:Octreotide