Somatostatin receptor imaging in vivo by planar scintigraphy facilitates the diagnosis of canine insulinomas.
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.
Garden
Oliver A
OA
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Reubi
Jean Claude
JC
Dykes
Nathan L
NL
Yeager
Amy E
AE
McDonough
Sean P
SP
Simpson
Kenneth W
KW
D000818:Animals; D001345:Autoradiography; D004283:Dog Diseases / Q000000981:diagnostic imaging*; D004285:Dogs; D007205:Indium Radioisotopes; D007340:Insulinoma / Q000000981:diagnostic imaging / Q000662:veterinary*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000662:veterinary*; D011877:Radionuclide Imaging; D017481:Receptors, Somatostatin / Q000502:physiology*
D007205:Indium Radioisotopes; D017481:Receptors, Somatostatin