title: 99mTc-EDDA/HYNIC-TOC in the diagnosis of differentiated thyroid carcinoma refractory to radioiodine treatment.
abstract: BACKGROUND
  In majority of cases of differentiated thyroid carcinoma (DTC), the ablative radioiodine treatment shows high efficacy. In a small number of patients, mechanism of selective iodine uptake by the DTC cells is insufficient and alternative methods of diagnosis and treatment are needed. As demonstrated in vitro, DTC cells show expression of somatostatin recep-tors. Radiolabeled somatostatin analogs are widely used in the diagnosis of neuroendocrine tumors. The aim of the study was to evaluate the utility of peptide receptor scintigraphy with the use of 99mTc-EDDA/HYNIC-TOC in the diagnosis of DTC in patients with elevated thyroglobulin concentrations (Tg), negative WBS and no effect of the consecutive radioiodine therapies.
  
  
  METHODS
  Whole body scintigraphy as well as SPECT of neck and chest were performed 3 and 24 h after i.v. administration of 740 MBq 99mTc-EDDA/HYNIC-TOC. The obtained images were compared with other radionuclide and ra-diological imaging methods. Forty-three patients with DTC after surgery and ablative radioiodine treatment with negative WBS and elevated Tg were qualified. Patients' age: 18-83 years (mean 58.0).
  
  
  RESULTS
  SRS showed foci of tracer accumulation in 29 cases (67.4%). Sensitivity was 69.0% specificity 78.6%. SRS correctly identified local recurrence in 8 pts., metastatic lymph nodes in 19 pts., lung metastases in 12 pts. and bone metastases in 5 pts. SRS showed high sensitivity in the detection of metastatic lymph nodes (100%) and bone metastases (83.3%) and lung metastases (63.2%). Positive SRS was found in pts. with higher Tg concentrations (130 ± 144 vs. 30 ± 54 ng/ml).
  
  
  CONCLUSIONS
  Scintigraphy with the use of the studied technetium-99m-labeled somatostatin analog is useful in the evaluation of patients with advanced DTC. It shows relatively good sensitivity and specificity but not high enough to be recommended as a routine imaging method. The role of somatostatin receptor scintigraphy in DTC is complementary to other imaging modalities.
authors.affiliation: Dept. of Endocrinology ang Metabolism, Poznan University of Medical Sciences. rafal.czepczynski@gmail.com.
authors.forename: Rafał
authors.initials: R
authors.lastname: Czepczyński
authors.forename: Maria
authors.initials: M
authors.lastname: Gryczyńska
authors.forename: Marek
authors.initials: M
authors.lastname: Ruchała
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004492:Edetic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives* / Q000737:chemistry; D015609:Organotechnetium Compounds / Q000737:chemistry*; D012008:Recurrence; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D015609:Organotechnetium Compounds; C410263:technetium Tc 99m hydrazinonicotinyl-Tyr(3)-octreotide; C026058:EDDA; D004492:Edetic Acid; D015282:Octreotide
keywords: scintigraphy; somatostatin analogs; thyroid carcinoma