title: 99mTc-N4-[Tyr3]Octreotate Versus 99mTc-EDDA/HYNIC-[Tyr3]Octreotide: an intrapatient comparison of two novel Technetium-99m labeled tracers for somatostatin receptor scintigraphy.
abstract: Tetraamine-[Tyr3]octreotate (Demotate) is a somatostatin (SST) analogue that can be easily labeled with 99mTc at high specific activities and showed promising preclinical properties for SST receptor scintigraphy. This study reports on the first intra-patient comparison of 99mTc-Demotate and another 99mTc-labeled SST analogue, 99mTc-EDDA/HYNIC-TOC (HYNIC-TOC). Five patients with carcinoid tumors (n = 2) and endocrine pancreatic tumors (n = 3) were investigated with both radiopharmaceuticals. 99mTc-Demotate rapidly visualized somatostatin receptor positive tumors as early as 15 minutes post-injection (p.i.) with maximum tumor uptake and tumor/organ ratios already 1 hour p.i. Organs of predominant physiological uptake were the spleen and the kidneys with no intestinal excretion detectable up to 24 hours. 99mTc-Demotate exhibited faster pharmacokinetic properties compared to HYNIC-TOC. Tumor/organ ratios at equivalent time points were higher or comparable for 99mTc-Demotate in three patients with a matching scan result. Equivocal findings were observed in two patients, i.e. comparable uptake behavior in larger lesions with differences in smaller ones. 99mTc-Demotate is a promising agent for somatostatin receptor scintigraphy providing images of excellent quality as early as 1 hour after injection.
authors.affiliation: Universität-Klinik für Nuklearmedizin, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Gabriel
authors.forename: Clemens
authors.initials: C
authors.lastname: Decristoforo
authors.forename: Theodosia
authors.initials: T
authors.lastname: Maina
authors.forename: Berthold
authors.initials: B
authors.lastname: Nock
authors.forename: Elisabeth
authors.initials: E
authors.lastname: vonGuggenberg
authors.forename: Paul
authors.initials: P
authors.lastname: Cordopatis
authors.forename: Roy
authors.initials: R
authors.lastname: Moncayo
mesh_terms: D000368:Aged; D002276:Carcinoid Tumor / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism; D010456:Peptides, Cyclic / Q000493:pharmacokinetics; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017481:Receptors, Somatostatin / Q000378:metabolism*; D013004:Somatostatin / Q000031:analogs & derivatives; D013667:Technetium / Q000493:pharmacokinetics; D014018:Tissue Distribution; D014915:Whole-Body Counting
chemical_list: D015609:Organotechnetium Compounds; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; C470036:octreotate, Tyr(3)-; C487389:technetium 99m EDDA-HYNIC-Tyr(3)-octreotide; C470035:technetium Tc 99m demotate; D013004:Somatostatin; D013667:Technetium