title: Improved Quantification of the Beta Cell Mass after Pancreas Visualization with99mTc-demobesin-4 and Beta Cell Imaging with111In-exendin-3 in Rodents.
abstract: Accurate assessment of the111In-exendin-3 uptake within the pancreas requires exact delineation of the pancreas, which is highly challenging by MRI and CT in rodents. In this study, the pancreatic tracer99mTc-demobesin-4 was evaluated for accurate delineation of the pancreas to be able to accurately quantify111In-exendin-3 uptake within the pancreas.
  
  
  
  Healthy and alloxan-induced diabetic Brown Norway rats were injected with the pancreatic tracer99mTc-demobesin-4 ([99mTc-N4-Pro1,Tyr4,Nle14]bombesin) and the beta cell tracer111In-exendin-3 ([111In-DTPA-Lys40]exendin-3). After dual isotope acquisition of SPECT images,99mTc-demobesin-4 was used to define a volume of interest for the pancreas in SPECT images subsequently the111In-exendin-3 uptake within this region was quantified. Furthermore, biodistribution and autoradiography were performed in order to gain insight in the distribution of both tracers in the animals.
  
  
  
  99mTc-demobesin-4 showed high accumulation in the pancreas. The uptake was highly homogeneous throughout the pancreas, independent of diabetic status, as demonstrated by autoradiography, whereas111In-exendin-3 only accumulates in the islets of Langerhans. Quantification of both ex vivo and in vivo SPECT images resulted in an excellent linear correlation between the pancreatic uptake, determined with ex vivo counting and111In-exendin-3 uptake, determined from the quantitative analysis of the SPECT images (Pearson r = 0.97, Pearson r = 0.92).
  
  
  
  99mTc-demobesin-4 shows high accumulation in the pancreas of rats. It is a suitable tracer for accurate delineation of the pancreas and can be conveniently used for simultaneous acquisition with111In labeled exendin-3. This method provides a straightforward, reliable, and objective method for preclinical beta cell mass (BCM) quantification with111In-exendin-3.
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center , PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Inge
authors.initials: I
authors.lastname: van der Kroon
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center , PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Lieke
authors.initials: L
authors.lastname: Joosten
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR Demokritos, GR-153 10 Agia Paraskevi, Attikis, Athens, Greece.
authors.forename: Berthold A
authors.initials: BA
authors.lastname: Nock
authors.affiliation: Molecular Radiopharmacy, INRASTES, NCSR Demokritos, GR-153 10 Agia Paraskevi, Attikis, Athens, Greece.
authors.forename: Theodosia
authors.initials: T
authors.lastname: Maina
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center , PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Otto C
authors.initials: OC
authors.lastname: Boerman
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center , PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Brom
authors.affiliation: Department of Radiology and Nuclear Medicine, Radboud University Medical Center , PO Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Martin
authors.initials: M
authors.lastname: Gotthardt
mesh_terms: D000818:Animals; D001345:Autoradiography; D001839:Bombesin / Q000737:chemistry*; D007205:Indium Radioisotopes / Q000737:chemistry*; D050417:Insulin-Secreting Cells / Q000166:cytology*; D010179:Pancreas / Q000000981:diagnostic imaging*; D010455:Peptides / Q000737:chemistry*; D051381:Rats; D000072098:Single Photon Emission Computed Tomography Computed Tomography / Q000379:methods*
chemical_list: D007205:Indium Radioisotopes; D010455:Peptides; C066448:exendin 3; D001839:Bombesin
keywords: beta cell mass; demobesin-4; exendin-3; pancreas imaging