title: Correlation of immunohistopathological expression of somatostatin receptor 2 with standardised uptake values in 68Ga-DOTATOC PET/CT.
abstract: OBJECTIVE
  In clinical routine somatostatin analogue positron emission tomography/computed tomography (PET/CT) such as (68)Ga-DOTA-Tyr-octreotide (DOTATOC)-PET/CT could substitute conventional (111)In-Octreotide scintigraphy. Immunohistochemistry (IHC) for somatostatin receptor 2 (SSTR2) might be a tool to predict positivity of (68)Ga-DOTATOC in patients where initial staging was not performed, e.g., in incidental findings. We therefore compared a score of SSTR2-IHC with the in vivo standard uptake value (SUV) of preoperative or prebiopsy (68)Ga-DOTATOC PET/CT.
  
  
  METHODS
  In 18 patients, (68)Ga-DOTATOC PET/CT scans were quantified with SUV calculations and correlated to a cell membrane-based SSTR2-IHC score (ranging from 0 to 3).
  
  
  RESULTS
  Negative IHC scores were consistent with SUV values below 10. Furthermore, all score 2 and 3 specimens corresponded with high SUV values (above 15).
  
  
  CONCLUSIONS
  SSTR2-IHC scores correlated well with SUV values and we propose to use SSTR2 immunohistochemistry in patients missing a preoperative PET scan to indicate (68)Ga-DOTATOC-PET/CT as method for restaging and follow-up in individual patients.
authors.affiliation: Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Ismaningerstrasse 22, 81675, München, Germany. mail@matthiasmiederer.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Miederer
authors.forename: Stefan
authors.initials: S
authors.lastname: Seidl
authors.forename: Andreas
authors.initials: A
authors.lastname: Buck
authors.forename: Klemens
authors.initials: K
authors.lastname: Scheidhauer
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Wester
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Aurel
authors.initials: A
authors.lastname: Perren
mesh_terms: D000328:Adult; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism; D015282:Octreotide / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D049268:Positron-Emission Tomography; D017481:Receptors, Somatostatin / Q000276:immunology* / Q000378:metabolism*; D012189:Retrospective Studies; D013945:Thymoma / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism; D014057:Tomography, X-Ray Computed
chemical_list: C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; D017481:Receptors, Somatostatin; C093733:somatostatin receptor 2; D015282:Octreotide