title: Specificity and sensitivity of ⁹⁹mTc-EDDA/HYNIC-Tyr³-octreotide (⁹⁹mTc-TOC) for imaging neuroendocrine tumors.
abstract: OBJECTIVE
  Gastroenteropancreatic neuroendocrine tumors (NETs) are cancers originating from neuroendocrine organs such as the pancreas, pituitary, thyroid, and adrenal glands and tumors arising from the diffuse neuroendocrine cells that are widely distributed throughout the body. NETs express somatostatin (SS) and contain a high density of SS receptors; therefore, they can be specifically targeted with SS-based radiopharmaceuticals. The aim of this research was to determine the validity in terms of specificity, sensitivity, and the agreement beyond chance with the biopsy (gold standard) of the ⁹⁹mTc-EDDA-HYNIC-Tyr³octreotide (⁹⁹mTc-TOC) to image and localize NETs and their metastases.
  
  
  METHODS
  Freeze-dried kits containing 0.0125 mg HYNIC-octreotide and co-ligands were easily labeled and quality controlled within the hospital radiopharmacy. Fifty-six consecutive Mexican patients with a previous presumptive diagnosis of NETs underwent several clinical and laboratory studies and were referred to the Nuclear Medicine Department for a routine scan with ⁹⁹mTc-TOC. The patients were injected with 500-600 MBq ⁹⁹mTc-TOC, and whole-body images were obtained 2 h later with a SPECT or a SPECT/CT camera. Two nuclear medicine physicians observed the images and classified them as 17 negative and 39 positive. After correlating the image of each patient with our 'gold standard' (biopsy, clinical history, morphological images, and tumor marker assays), the ⁹⁹mTc-TOC images were classified by the same two physicians as 12 true negatives, five false negatives, 38 true positives and one false positive.
  
  
  RESULTS
  The validity of ⁹⁹mTc-TOC in terms of relative frequencies with corresponding 95% confidence intervals were as follows: 92.3% (64-100%) specificity; 88.4% (78-97%) sensitivity; and the agreement beyond chance was 73% (60-84%). The positive predictive value was 97.4% (87-100%); the negative predicted value was 70.6% (48-93%); the accuracy was 89.3% (89-97%); and the prevalence was 76.8% (64-87%).
  
  
  CONCLUSIONS
  Because of these high values, we strongly recommend scintigraphy with the Mexican-produced ⁹⁹mTc-TOC for the localization of NETs and their metastases, and we conclude that it is a good tool for detecting neuroendocrine disease in a Mexican population.
authors.affiliation: Departamento de Medicina Nuclear, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Delegación Tlalpan, México DF, México.
authors.forename: Jesús
authors.initials: J
authors.lastname: Sepúlveda-Méndez
authors.forename: Consuelo Arteaga
authors.initials: CA
authors.lastname: de Murphy
authors.forename: Martha
authors.initials: M
authors.lastname: Pedraza-López
authors.forename: Eduardo
authors.initials: E
authors.lastname: Murphy-Stack
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Rojas-Bautista
authors.forename: Ofelia
authors.initials: O
authors.lastname: González-Treviño
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004067:Digestive System Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000556:secondary; D015609:Organotechnetium Compounds; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging; D055815:Young Adult
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C487389:technetium 99m EDDA-HYNIC-Tyr(3)-octreotide