title: A gamma detector probe with ex vivo detection of carcinoid tumors superior to intraoperative palpation.
abstract: BACKGROUND
  Despite the generally successful scintigraphic detection of endocrine tumors with [(111)In]-DTPA-D-[Phe1]-octreotide (OctreoScan, Mallinckrodt Medical, Petten, The Netherlands), its intraoperative application awaits the development of suitable gamma detectors. This study describes a novel probe (H-probe2) and its ex vivo efficacy for the detection of midgut carcinoid tumors.
  
  
  METHODS
  The probe measures 180 mm x 24 mm, and contains a bismuth germinate crystal connected to a photomultiplicator tube, a lead shield, and a tantalum collimator with an angled, 3-mm wide opening. It was characterized in a test bench utilizing solublilized (111)In and 99mTc, and 8 fresh operative specimens containing 26 histologically verified midgut carcinoid tumors (2-40 mm) from patients exposed to OctreoScan. Measurements were made at 2.5-mm intervals over the entire specimens and presented three dimensionally.
  
  
  RESULTS
  The test bench analysis supported efficient shielding, and a total collimation of 27 degrees for (111)In and 20 degrees for 99mTc. In addition to 18 palpable tumors, 4 of 6 surgically occult tumors (2-3 mm in dimension) could be discovered with H-probe2. Small tumors in close apposition to a large tumor could not be separated. Wellcounter examination showed that tumors detected with the H-probe2 exhibited 1.7-84.1 times higher radionuclide uptake than the surrounding normal tissue.
  
  
  CONCLUSIONS
  Ex vivo analysis of H-probe2 supported detection of tumors inaccessible to surgical palpation, but its clinical efficiency awaits intraoperative evaluation.
authors.affiliation: Department of Surgery, Uppsala University Hospital, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Ohrvall
authors.forename: J E
authors.initials: JE
authors.lastname: Westlin
authors.forename: F
authors.initials: F
authors.lastname: Kjellberg
authors.forename: S
authors.initials: S
authors.lastname: Nilsson
authors.forename: C
authors.initials: C
authors.lastname: Juhlin
authors.forename: J
authors.initials: J
authors.lastname: Rastad
authors.forename: G
authors.initials: G
authors.lastname: Akerström
authors.forename: H
authors.initials: H
authors.lastname: Lundqvist
mesh_terms: D002276:Carcinoid Tumor / Q000000981:diagnostic imaging*; D015902:Gamma Cameras; D006801:Humans; D007205:Indium Radioisotopes; D007414:Intestinal Neoplasms / Q000000981:diagnostic imaging*; D007432:Intraoperative Period; D015282:Octreotide; D010173:Palpation; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007205:Indium Radioisotopes; D015282:Octreotide