title: Multiparametric PET imaging in thyroid malignancy characterizing tumour heterogeneity: somatostatin receptors and glucose metabolism.
abstract: OBJECTIVE
  Radiolabelled somatostatin (SST) analogues have proven useful in diagnosing tumours positive for SST receptor (SSTR). As different subtypes of SSTR are expressed on the tumour cell surface, the choice of appropriate therapeutic SST analogue is crucial. We evaluated the SSTR status of thyroid cancer patients who had signs of progressive disease comparing different SSTR ligands for PET imaging to evaluate possible further therapeutic options.
  
  
  METHODS
  PET with (68)Ga-radiolabelled SSTR ligands DOTA lanreotide (DOTA-LAN), DOTA-Tyr(3) octreotide (DOTA-TOC) and (18)F-FDG was performed in 31 patients with thyroid cancer (TC). These 31 patients comprised 18 with radioiodine non-avid differentiated TC (DTC) including 6 papillary TC (PTC), 8 follicular TC (FTC) and 4 oxyphilic TC (oxyTC), 5 with anaplastic TC (ATC), and 8 with medullary TC (MTC). The PET results were compared in a region-based evaluation.
  
  
  RESULTS
  All patients underwent a PET study with (68)Ga-DOTA-LAN, 28 patients with (68)Ga-DOTA-TOC and 28 patients with (18)F-FDG. A lack of SSTR expression was found in 13 of the 31 patients (42%) with negative results with both SSTR tracers in 12 patients. Ambiguous results with both SSTR tracers were observed in one patient. High tracer uptake in SSTR PET images was seen in seven DTC patients (39%; two PTC, three FTC, two oxyTC), in four ATC patients (80%) and in six MTC patients (75%). Lesions showing aerobic glycolysis on (18)F-FDG PET were found in 24 of 28 patients (86%) with corresponding positive results with (68)Ga-DOTA-LAN in 35% and with (68)Ga-DOTA-TOC in 29%.
  
  
  CONCLUSIONS
  The heterogeneous SSTR profile of TC tumour lesions needs to be evaluated using different SSTR PET tracers to characterize more closely the SSTR subtype affinities in patients with progressive TC in order to further stratify therapy with SSTR therapeutics.
authors.affiliation: Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.|Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Traub-Weidinger
authors.affiliation: Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Putzer
authors.affiliation: Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: von Guggenberg
authors.affiliation: Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Dobrozemsky
authors.affiliation: Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Nilica
authors.affiliation: Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
authors.forename: Dorota
authors.initials: D
authors.lastname: Kendler
authors.affiliation: Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Reto
authors.initials: R
authors.lastname: Bale
authors.affiliation: Department of Nuclear Medicine, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria. irene.virgolini@i-med.ac.at.
authors.forename: Irene Johanna
authors.initials: IJ
authors.lastname: Virgolini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006573:Heterocyclic Compounds, 1-Ring; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology
chemical_list: C400086:DOTALAN; C499142:Ga(III)-DOTATOC; D006573:Heterocyclic Compounds, 1-Ring; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; D019788:Fluorodeoxyglucose F18; D005947:Glucose; D015282:Octreotide
keywords: 68Ga-DOTA-LAN; 68Ga-DOTA-TOC; Somatostatin receptor PET imaging; Thyroid cancer