Somatostatin receptor imaging in vivo by planar scintigraphy facilitates the diagnosis of canine insulinomas.

Abstract

Somatostatin receptors expressed by insulinomas in 5 dogs were imaged in vivo by means of indium in 111 pentetreotide (OctreoScan) scintigraphy. The diagnosis in each dog was supported by the presence of hypoglycemia (<60 mg/dL), hyperinsulinemia (>20 microU/mL), and histopathologic review of neoplastic tissue. All insulinomas expressed high-affinity somatostatin receptors of subtype sst2, as shown by receptor autoradiography in vitro using 125I-[tyrosine3]-octreotide and 125I-[leucine8, Dtryptophan22, tyrosine25]-somatostatin-28 with an sst2 subtype-selective analogue. Scintigrams were obtained at 1, 4, 12, and 24 hours after the i.v. administration of 74-222 MBq of OctreoScan to each patient. Abnormal foci of activity were 1st observed from 1 hour after administration of the radioligand in dog 3, to 24 hours after its administration in dog 4; in dogs 1 and 2, abnormal foci of activity were visible from 12 hours. Dog 5 showed a questionable abnormal focus of activity at 12 hours, but not at 24 hours. Scintigraphy enabled accurate prediction of the anatomical location of the primary tumor in 1 of 4 dogs, but was unable to differentiate a right- from a left-pancreatic lobe tumor, or vice versa, in 3 dogs; the 5th dog had equivocal results. 111In-pentetreotide scintigraphy is a useful diagnostic adjunct to the clinical evaluation of the insulinoma patient, but is unable to localize the tumor in some cases.

• Authors: Oliver A Garden, Jean Claude Reubi, Nathan L Dykes, Amy E Yeager, Sean P McDonough, Kenneth W Simpson
• Journal: Journal of veterinary internal medicine (J Vet Intern Med) 2005 Mar-Apr Vol. 19 Issue 2 Pg. 168-76 ISSN: 0891-6640 [Print] United States
• PMID: 15822560 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Indium Radioisotopes
• Receptors, Somatostatin

Topics

• Animals
• Autoradiography
• Dog Diseases (diagnostic imaging)
• Dogs
• Indium Radioisotopes
• Insulinoma (diagnostic imaging, veterinary)
• Pancreatic Neoplasms (diagnostic imaging, veterinary)
• Radionuclide Imaging
• Receptors, Somatostatin (physiology)