title: Limitations of somatostatin scintigraphy in primary small bowel neuroendocrine tumors.
abstract: BACKGROUND
  Somatostatin receptor scintigraphy (SRS; octreoscan) is used in neuroendocrine tumors to locate the primary tumor site and delineate the extent of disease. SRS has decreased sensitivity for small bowel neuroendocrine tumors (SBNETs). The reasons for SRS nonlocalization are not clear. We sought to determine factors that correlate with successful primary tumor localization by SRS in patients with resected SBNETs, and also identify factors that confound interpretation of SRS reports.
  
  
  METHODS
  Records of patients with resected SBNETs were reviewed for SRS results, tumor size, multifocality, N, and M status. Somatostatin receptor 2 (SSTR2) expression was analyzed in resected tumors by quantitative polymerase chain reaction. SRS reports were reviewed and categorized as localizing the primary tumor or not. A nuclear medicine physician independently reviewed available images.
  
  
  RESULTS
  Of 37 patients with preoperative SRS, the primary tumor was localized in 37%. Of all the factors tested, only small tumor size correlated significantly with SRS nonlocalization. Overexpression of SSTR2 was not significantly different between tumors that were or were not localized by SRS, regardless of tumor size. There were three instances where the SRS report did not agree with the nuclear medicine physician's interpretation as to whether SRS localized the primary tumor. In each case, uptake in mesenteric nodes was a confounding factor.
  
  
  CONCLUSIONS
  SBNETs <2 cm are most likely to be missed by SRS. SSTR2 expression did not correlate with SRS nonlocalization of the primary tumor. Uptake in mesenteric nodes may help indicate an SBNET primary but can also interfere with its visualization within the small bowel.
authors.affiliation: Department of General Surgery, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors.forename: Jessica E
authors.initials: JE
authors.lastname: Maxwell
authors.affiliation: Department of General Surgery, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors.forename: Scott K
authors.initials: SK
authors.lastname: Sherman
authors.affiliation: Department of Radiology, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Menda
authors.affiliation: Department of General Surgery, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors.forename: Donghong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: O'Dorisio
authors.affiliation: Department of General Surgery, University of Iowa Carver College of Medicine, Iowa City, Iowa. Electronic address: james-howe@uiowa.edu.
authors.forename: James R
authors.initials: JR
authors.lastname: Howe
mesh_terms: D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D007421:Intestine, Small / Q000473:pathology*; D008297:Male; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin / Q000032:analysis* / Q000378:metabolism; D012042:Registries; D012189:Retrospective Studies
chemical_list: D017481:Receptors, Somatostatin; C574734:SSTR2 protein, human
keywords: Octreoscan; SSTR2 expression; Small bowel neuroendocrine tumor; Somatostatin scintigraphy